Tokugawa Ieyasu#Ruler of Japan (1598–1603)

Tokugawa Ieyasu was born in Okazaki Castle on the 26th day of the twelfth month of the eleventh year of Tenbun, according to the Japanese calendar, January 31, 1543 according to the Western calendar. Originally named {{Nihongo|Matsudaira Takechiyo|松平 竹千代}}, he was the son of {{Nihongo|Matsudaira Hirotada|松平 広忠}}, the daimyo of Mikawa of the Matsudaira clan, and {{Nihongo|Odai no Kata|於大の方|extra=Lady Odai}}, the daughter of a neighbouring samurai lord, {{Nihongo|Mizuno Tadamasa|水野 忠政}}. His mother and father were step-siblings. They were 17 and 15 years old, respectively, when Takechiyo was born.{{Cite book|last=McLynn|first=Frank|url=https://books.google.com/books?id=64vwz3O4QgwC&q=tokugawa+Ieyasu+11+half-brothers+and+sisters&pg=PA230|title=Heroes & Villains: Inside the minds of the greatest warriors in history|date=2009|publisher=Random House|isbn=978-1-4090-7034-4|page=230|language=en}}

During the Muromachi period, the Matsudaira clan controlled a portion of Mikawa Province (the eastern half of modern Aichi Prefecture). Ieyasu's father, Matsudaira Hirotada, was a minor local warlord based at Okazaki Castle who controlled a portion of the Tōkaidō highway linking Kyoto with the eastern provinces. His territory was surrounded by stronger and predatory neighbors, including the Imagawa clan based in Suruga Province to the east and the Oda clan to the west. Hirotada's main enemy was Oda Nobuhide, the father of Oda Nobunaga.{{Cite book |last=Turnbull |first=Stephen |title=Tokugawa Ieyasu |publisher=Osprey Publishing |year=2012 |isbn=9781849085748 |pages=5–9}}

In the year of Takechiyo's birth, the Matsudaira clan split. Hirotada's uncle, Matsudaira Nobutaka defected to the Oda clan. This gave Oda Nobuhide the confidence to attack Okazaki. Soon afterwards, Hirotada's father-in-law died, and his heir, Mizuno Nobumoto, revived the clan's traditional enmity against the Matsudaira and declared allegiance to Oda Nobuhide as well. As a result, Hirotada divorced Odai-no-kata and sent her back to her family. Hirotada later remarried to different wives, and Takechiyo eventually had 11 half-brothers and sisters.

File:Okazakijo2.JPG, the birthplace of Tokugawa Ieyasu]]

As Oda Nobuhide continued to attack Okazaki, Hirotada turned to his powerful eastern neighbor, Imagawa Yoshimoto, for assistance. Yoshimoto agreed to an alliance under the condition that Hirotada send his young heir to Sunpu Domain as a hostage. Oda Nobuhide learned of this arrangement and had Takechiyo abducted. Takechiyo was five years old at the time.Screech, Timon (2006). Secret Memoirs of the Shoguns: Isaac Titsingh and Japan, 1779–1822. London: RoutledgeCurzon. {{ISBN|0-7007-1720-X}}, pp. 85, 234; n.b., Screech explains

Minamoto-no-Ieyasu was born in Tenbun 11, on the 26th day of the 12th month (1542) and he died in Genna 2, on the 17th day of the 4th month (1616); and thus, his contemporaries would have said that he lived 75 years. In this period, children were considered one year old at birth and became two the following New Year's Day; and all people advanced a year that day, not on their actual birthday.

In 1549, when Takechiyo was six, his father Hirotada died of unknown causes. There was a popular theory that he was murdered by his vassals, who had been bribed by the Oda clan. However, a scholarly article published by Muraoka Mikio in 2015 states that the assassination theory is unreliable and Hirotada's death may have been caused by a natural illness.{{Cite journal|author=Muraoka Mikio |title=織田信秀岡崎攻落考証|journal=中京大学文学論叢|issue=1|date=2015}}

Around the same time, Oda Nobuhide died during an epidemic. Nobuhide's death dealt a heavy blow to the Oda clan.

In 1551, an army under the command of Imagawa Sessai laid siege to the castle where Oda Nobuhiro, Nobuhide's illegitimate eldest son, was living. Nobuhiro was trapped by the Imagawa clan but was saved through negotiation by Oda Nobunaga, Nobuhide's second son and heir. Sessai made an agreement with Nobunaga to take Takechiyo back to Imagawa, and he agreed. Takechiyo, now nine years old, was taken as a hostage to Sunpu.

At Sunpu, he was treated fairly well as a potentially useful ally of the Imagawa clan until 1556 when he was 14 years old. Yoshimoto decided that the Matsudaira clan's territory would be inherited by Takechiyo in the future, with the aim that the Imagawa clan could rule the area by extensions of their Matsudaira clan as their vassal, including Zuien-in (the daughter of Matsudaira Nobutada and Takechiyo's great-aunt), who was the only member of the Anjo Matsudaira clan left in Okazaki Castle.Shinko Kiichi, "Okazaki under the control of the castle lord and Matsudaira Motoyasu, a subordinate of the Imagawa clan," New Edition of the History of Okazaki City, Middle Ages, Chapter 3, Section 4, Items 5 and 6, 1989.... Here, Okazaki quoted ishi in his book Oishi, Yasushi (2019). 今川義元 [Imagawa Yoshimoto]. シリーズ・中世関東武士の研究 第二七巻. 戎光祥出版{{sfn|Oishi|2019|pp=134–141}}{{efn|In addition, during this time of hostages in Sunpu, Hojo Ujinori of Hōjō clan was also a hostage in Sunpu castle, so there is a theory that Ieyasu and Ujinori had been friends since that time, and this theory was included in the Dai Nihon Shiryō (collection of historical documents from the ninth to the seventeenth century) and other sources.Suruga Magazine (a geography book of Suruga Province in the early 19th century, written by Abe Masanobu)}}

{{Main|Siege of Marune|Battle of Okehazama|Siege of Kaminogo Castle}}

In 1556, Takechiyo officially came of age, with Imagawa Yoshimoto presiding over his genpuku ceremony. Following tradition, he changed his name from Matsudaira Takechiyo to {{Nihongo|Matsudaira Jirōsaburō Motonobu|松平 次郎三郎 元信}}. He was also briefly allowed to visit Okazaki to pay his respects to the tomb of his father, and receive the homage of his nominal retainers, led by the karō Torii Tadayoshi.

One year later, at the age of 15 (according to East Asian age reckoning), he married his first wife, Lady Tsukiyama, a relative of Imagawa Yoshimoto, and changed his name again to {{Nihongo|Matsudaira Kurandonosuke Motoyasu|松平 蔵人佐 元康}}. A year later, their son, Matsudaira Nobuyasu, was born. He was then allowed to return to Mikawa Province. There, the Imagawa ordered him to fight against the Oda clan in a series of battles.{{Cite book |last=Bottomley |first=Ian |url=https://www.worldcat.org/oclc/63666433 |title=Shogun: the life of Lord Tokugawa Ieyasu |date=2005 |publisher=Royal Armouries |others=Royal Armouries Museum |isbn=0-948092-58-0 |location=Leeds, UK |oclc=63666433}}

Motoyasu fought his first battle in 1558 at the siege of Terabe. The lord of Terabe, Suzuki Shigeteru (or {{ill|Suzuki Shigetatsu|jp|鈴木重辰 (日向守)|vertical-align=sup}}), betrayed the Imagawa by defecting to Oda Nobunaga. This was nominally within Matsudaira territory, so Imagawa Yoshimoto entrusted the campaign to Motoyasu and his retainers from Okazaki. Motoyasu led the attack in person, but after taking the outer defences, he burned the main castle and withdrew. As anticipated, the Oda forces attacked his rear lines, but Motoyasu was prepared and drove off the Oda army.{{Cite book |last=Turnbull |first=Stephen |title=Tokugawa Ieyasu |publisher=Osprey Publishing |year=2012 |isbn=9781849085748 |page=10}}

He then succeeded in delivering supplies during the siege of Odaka Castle a year later. Odaka was one of five disputed frontier forts under attack by the Oda clan, and the only one that still remained under Imagawa control. Motoyasu launched diversionary attacks against the two neighboring forts and, when the garrisons of the other forts came to assist, Motoyasu's supply column was able to reach Odaka.{{sfn|Turnbull |1998 |p=215}}

By 1559, the leadership of the Oda clan had passed to Oda Nobunaga. In 1560, Imagawa Yoshimoto, leading a large army of 25,000 men, invaded Oda territory. Motoyasu was assigned a separate mission to capture the stronghold of Marune in the Siege of Marune operation. As a result, he and his men were not present at the Battle of Okehazama where Yoshimoto was killed in a surprise assault by Nobunaga,{{rp|37}} In the end, Motoyasu managed to capture Marune castle.{{sfn|Honda |2010|p=56}}

Later, in response to the news of Yoshimoto's death, Motoyasu sent lookouts to check the state of the battle and then retreated from Odaka Castle at midnight. After leaving Odaka Castle, Motoyasu's forces headed for Okazaki with Asai Michitada as their guide. On the way, they were stopped by the Mizuno clan's forces at Chiryu, but because Asai Michitada was with them, they were not attacked. Having escaped from danger, Motoyasu entered Daijuji Temple outside Okazaki Castle the following day.{{cite web |author1=Yasutsune Owada (小和田泰経) |author2=Rekishijin Editorial Department |title=実は徳川家康は、桶狭間の戦いで今川方として獅子奮迅の活躍をしていた！|trans-title=In fact, Tokugawa Ieyasu fought bravely on the Imagawa side in the Battle of Okehazama! |url=https://www.rekishijin.com/26834 |website=Rekishijin |publisher=ABC ARC, inc. |access-date=24 June 2024 |language=Ja |date=2023 |quote=From "The Truth About Tokugawa Ieyasu" in the February 2023 issue of Rekishijin article}}

With Imagawa Yoshimoto dead, and the Imagawa clan in a state of confusion, Motoyasu used the opportunity to assert his independence and marched his men back into the abandoned Okazaki Castle and reclaimed his ancestral seat. Motoyasu then decided to ally with Oda Nobunaga.{{Cite book|last =Turnbull |first= Stephen R. |title= The Samurai: A Military History |publisher=MacMillan Publishing Co. |place=New York |year =1977|page= 144}} Motoyasu's wife, Lady Tsukiyama, and infant son, Matsudaira Nobuyasu, were held hostage in Sunpu by Imagawa Ujizane, Yoshimoto's heir, so the deal was secret.{{Cite book |last=Bottomley |first=Ian |url=https://www.worldcat.org/oclc/63666433 |title=Shogun : the life of Lord Tokugawa Ieyasu |date=2005 |publisher=Royal Armouries |others=Royal Armouries Museum |isbn=0-948092-58-0 |location=Leeds, UK |pages=12 |oclc=63666433}}

In 1561, Motoyasu openly ended his allegiance to the Imagawa clan and captured Kaminogō castle. Kaminogō was held by Udono Nagamochi. Resorting to stealth, Motoyasu forces under Hattori Hanzō attacked under cover of darkness, setting fire to the castle and capturing two of Udono's sons. He then used them as hostages to exchange for his wife and son.{{sfn|Turnbull |1998 |p=216}}

Sometime in the aftermath of the Okehazama battle where Imagawa Yoshimoto was slain, Motoyasu formed the {{ill|Kiyosu Alliance|jp|清洲同盟}} with Oda Nobunaga, daimyo lord of Owari Province and the head of the Oda clan.{{Cite journal|author=Masaki Anno |title=鋳物師水野太郎左衛門 |journal=弘前大学教育学部研究紀要クロスロード |issn=1345-675X |publisher=弘前大学教育学部 |date=2002 |issue=6 |pages=1–15 |hdl=10129/2159 |url=https://hdl.handle.net/10129/2159 }}{{Cite journal|author=Masaki Anno |title=瀬戸宛て信長制札 |journal=弘前大学教育学部紀要 |issn=0439-1713 |publisher=弘前大学教育学部 |date=2004 |issue=91 |pages=15–26 |hdl=10129/2162 |url=https://hdl.handle.net/10129/2162}}{{efn|Historians cannot reach consensus about the exact date when the alliance was officially proclaimed. Some have said the alliance was established two years after the Okehazama battle, although Ieyasu himself did not attend personally to the Kiyosu castle, since there are no historical records about his visit during this time.{{Cite web|title=織田信長と徳川家康が結んだ「清須同盟」は幻だった⁉ 徳川家康の真説 |url=https://www.rekishijin.com/25015|website=歴史人|access-date=2023-02-02}} Other theories from Akio Hirano deduced the alliance only formally announced in 1573.{{Cite journal|author=Hirano Akio |title=戦国期徳川氏の政治的立場--織田氏との係わりを通して |journal=国史学 |issn=0386-9156 |publisher=国史学会 |date=1995 |issue=158 |pages=97–128 }}}}

In 1563, Matsudaira Nobuyasu, the first son of Motoyasu, was married to Oda Nobunaga's daughter Tokuhime.{{Page needed|date=June 2024}}{{efn|Tetsuo Owada stated the marriage between Nobuyasu and Tokuhime occurred in 1567, when both was nine years old.{{harvtxt|Tetsuo Owada|2002|p=24}}}} In February, Matsudaira Motoyasu changed his name to Matsudaira Ieyasu.{{cite book |last=Pitelka |first=Morgan |title=Spectacular Accumulation: Material Culture, Tokugawa Ieyasu, and Samurai Sociability |date=2015 |publisher=University of Hawai'i Press |isbn=9780824851576}}{{Page needed|date=June 2024}}{{Cite book|last=Brinkley|first=Frank & Kikuchi|url=https://books.google.com/books?id=bzRen1dcdTwC&q=Tokugawa+Ieyasu,February,changed+his+name&pg=PT818|title=A History of the Japanese People From the Earliest Times to the End of the Meiji Era|date=1912|publisher=Library of Alexandria|isbn=978-1-4655-1304-5|language=en}} Some historians believe that these actions provoked the pro-Imagawa faction, including the Sakurai and Okusa Matsudaira families, which led to the simultaneous uprising against Ieyasu in the following year.{{Sfn|Shiba|2021|p=23 quoting "General Overview: Tokugawa Ieyasu's Movements and Research in the Sengoku and Oda-Momoyama Periods"}}

{{Main|Mikawa province}}

File:Azukizaka 1564.JPG print depicting the Battle of Batogahara between Tokugawa clan against Ikkō-ikki movement in 1563–1564.]]

During this period, the Matsudaira clan faced a threat from the Ikkō-ikki movement, in which peasants banded together with militant monks under the Jōdo Shinshū sect, and rejected the traditional feudal social order. Ieyasu undertook several battles to suppress this movement in his territories, including the Battle of Azukizaka (1564).

Some of Ieyasu's vassals were in the Ikkō-ikki ranks, notablyHonda Masanobu and Natsume Yoshinobu, who had deserted him for the Ikkō-ikki rebellion out of religious sympathy.{{sfn|Turnbull |1998 |p=216}} However, many of Ieyasu's core vassals who were also followers of the sect, such as Ishikawa Ienari{{Cite book|author=Sunao Kawaguchi (川口素生)|title=戦国軍師人名事典|publisher=学習研究社|date=2009|page=302}} and Honda Tadakatsu, quickly abandoned the Ikkō faith of Jōdo Shinshū and stayed loyal to Ieyasu in order to confront the rebels.{{harvtxt|Stephen Turnbull |2012 |pp=13, 27, 34}}{{cite book |author1=Tadachika Kuwata |title=日本の合戦. 第5巻 (織田信長) |trans-title=Battle of Japan Volume 5 (Oda Nobunaga) |date=1965 |publisher=人物往来社 |location=Tokyo |page=207 |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000000867858 |access-date=23 May 2024 |language=Ja}}

On January 15, 1564, Ieyasu decided to concentrate his forces to attack and eliminate the Ikkō-ikki from Mikawa. In the Battle of Azukizaka, Ieyasu was fighting on the front lines and was nearly killed when he was struck by several bullets, but survived because they did not penetrate his armor. Both sides were using new gunpowder weapons which the Portuguese had introduced to Japan 20 years earlier. At the end of battle, the Ikkō-ikki were defeated. By 1565, Ieyasu had become the master of all of Mikawa Province.{{Citation needed|date=May 2024}}

In 1566, as Ieyasu declared his independence from the Imagawa clan, he reformed the order of Mikawa province, starting with the Matsudaira clan, after he pacified Mikawa. This decision was made after he was counseled by his senior vassal Sakai Tadatsugu to abandon the clan's allegiance to the Imagawa clan.{{harvtxt|Arthur Lindsay Sadler |2014|p=57}} He also strengthened his power base by creating a military government system for the Tokugawa clan in Mikawa which was based on his hereditary vassals, the Fudai daimyō. The system which was called "Sanbi no gunsei" (三備の軍制) divided governance into three sections:{{cite book |author1=Tamotsu Fujino |title=徳川政権と幕閣 |trans-title=Tokugawa government and Bakufu |date=1995 |publisher=新人物往来社 |location=11 |url=https://books.google.com/books?id=SYINAQAAMAAJ |access-date=27 May 2024 |language=Ja}}{{cite book |author1=Tamotsu Fujino |title=徳川幕閣: 武功派と官僚派の抗争 |trans-title=Tokugawa Shogunate: Conflict between the military faction and the bureaucratic faction |date=1967 |publisher=中央公論社 |pages=16, 29 |url=https://books.google.com/books?id=DnJDAAAAYAAJ |access-date=27 May 2024 |language=Ja}}{{cite book |author1=Rizō Takeuchi |title=角川日本地名大辞典: 愛知県 |trans-title= |date=1978 |publisher=Kadokawa Shoten |page=41 |url=https://books.google.com/books?id=ZgMRAQAAMAAJ |access-date=27 May 2024 |language=Ja}}

1. Hatamoto-Senshi: Ieyasu's direct vassals and personal unit of the army. Their task was to personally protect Ieyasu. The earliest commanders of this unit included Matsudaira Ietada (Tojo), Torii Mototada, Honda Tadakatsu, Sakakibara Yasumasa, Ōkubo Tadayo, Osuga Yasutaka, Uomura Iezumi, and others
2. Higashi Mikawa: The eastern Mikawa province army unit, put under the control of Sakai Tadatsugu as overall commander. The commanders of this unit consisted of many Matsudaira clansmen and other hereditary vassals of Tokugawa such as Matsudaira Ietada (Fukōzu), Matsudaira Tadamasa, Matsudaira Ietada (Katahara), and others
3. Nishi-Mikawa: The western Mikawa province army unit, put under the de jure control of Ishikawa Ienari (de facto control lay with his nephew, Ishikawa Kazumasa) as overall commander. The commanders of this unit consisted of many Matsudaira clansmen and other hereditary vassals which assigned on eastern side of the province, such as Shimada Heizo, Hiraiwa Chikayoshi, Naitō Ienaga, Sakai Tadatoshi, Matsudaira Shinichi, and others.

{{Main|Tokugawa clan}}

In 1567, Ieyasu started the family name "Tokugawa", changing his name to the well-known Tokugawa Ieyasu. As a member of the Matsudaira clan, he claimed descent from the Seiwa Genji branch of the Minamoto clan. As there was no proof that the Matsudaira clan were descendants of Emperor Seiwa,Screech, Timon (2006). Secret Memoirs of the Shoguns: Isaac Titsingh and Japan, 1779–1822. London: RoutledgeCurzon. {{ISBN|0-7007-1720-X}}, p. 82. the Emperor initially did not approve the appointment, citing the lack of a precedent for the Serada clan of the Seiwa Genji clan to be appointed as Mikawa-no-kami (Lord of Mikawa).{{Cite book|author=Taniguchi Kengo|title=流浪の戦国貴族 近衛前久 - 天下一統に翻弄された生涯 |trans-title=A Life at the Mercy of National Unification |series=中公新書|date=1994|pages=167–176}}

Ieyasu then consulted with imperial noble Konoe Motohisa through the mediation of a Mikawa native and the abbot of the Kyo Seiganji Temple.{{cite web |title=徳川」への改姓と「家康」への改名」『徳川家康 将軍家蔵書からみるその生涯』|trans-title=Tokugawa Ieyasu: His Life as Seen in the Shogun Family Library |url=https://www.archives.go.jp/exhibition/digital/ieyasu/contents1_04/ |website=archives.go.jp |publisher=National archives of Japan |access-date=29 May 2024 |language=Ja}} Due to Motohisa's efforts, Yoshida Kaneyoshi discovered a genealogical document in the Manri-koji family that was precedent, saying, "Tokugawa (belongs) to Minamoto clan, as another offshoot of the Fujiwara clan," and a copy was transferred to him and used for the application. Ieyasu then gained the permission of the Imperial Court and he was bestowed the courtesy title Mikawa-no-kami and the court rank of {{Nihongo|Junior 5th Rank, Lower Grade|從五位下|ju go-i no ge}}.

Though the Tokugawa clan could claim some modicum of freedom, they were very much subject to the requests of Oda Nobunaga. Ieyasu remained an ally of Nobunaga and his Mikawa soldiers were part of Nobunaga's army which captured Kyoto in 1568.

In 1568, at the same time, Ieyasu was eager to expand eastward to Tōtōmi Province. Ieyasu and Takeda Shingen, the head of the Takeda clan in Kai Province, made an alliance for the purpose of conquering all the Imagawa territory.{{rp|279}} It is said{{Who|date=September 2024}} that the Tokugawa clan had made an agreement with the Takeda clan when dividing the territory that the eastern Suruga Province would become Takeda territory and the western Tōtōmi province would be Tokugawa territory, with the Ōi River as the border.

On January 8, 1569, the Takeda vassal Akiyama Nobutomo invaded the Tōtōmi province from Shinano Province. The Takeda clan, through Oda Nobunaga, with whom they had a friendly relationship, asked Ieyasu, who was Nobunaga's ally, to reconsider cooperation with the Takeda, but Ieyasu rejected the idea, demonstrating a degree of independence from Nobunaga.

In 1568, Ieyasu besieged the Horikawa Castle in Tōtōmi{{cite book |title=新編岡崎市史: Sōshū hen Volume 20 of New edition of Okazaki City History |date=1983 |publisher=新編岡崎市史編さん委員会 |location=Okazaki City |page=59 |url=https://books.google.com/books?id=j3VMAQAAIAAJ |access-date=24 May 2024 |language=Ja}} and captured it in 1569. Ieyasu then ordered Ishikawa Hanzaburo to massacre the castle prisoners and residents, including women and children. It was recorded that around 700 people were beheaded on the banks of the Miyakoda River.* {{Cite book|last= Kamefumi Naito|date= 1972 |chapter= 姫街道の今昔 |editor=静岡新聞社 |title= ふるさと百話 |publisher= 静岡新聞社 |volume= 7 |pages= 155–159}} Ōkubo Tadachika, who witnessed this massacre testified in his personal journal, Mikawa Monogatari, that "... {{sic|both mens and womens can be cut into pieces}}...".{{citation |publisher=Hosoe town Board of Education |location=Horikawa castle Ruin |language=Ja |title=Mikawa Monogatari}}

Later the same year, Ieyasu's troops penetrated Tōtōmi Province. Meanwhile, Takeda Shingen's troops captured Suruga Province, including the Imagawa capital of Sunpu. Imagawa Ujizane fled to Kakegawa Castle, which led Ieyasu to lay siege to Kakegawa.

Ieyasu then negotiated with Ujizane, promising that if Ujizane surrendered himself and the remainder of Tōtōmi, Ieyasu would assist Ujizane in regaining Suruga. Ujizane had nothing left to lose, and Ieyasu immediately ended his alliance with Takeda, instead making a new alliance with Takeda's enemy to the north, Uesugi Kenshin of the Uesugi clan. Through these political manipulations, Ieyasu gained the support of the samurai of Tōtōmi Province. Furthermore, Ieyasu also placed the "Iinoya's trio" (Iinoya-Sanninshu) of clans under the command of his trusted vassal, Ii Naomasa.{{Cite web|url=https://www.city.shinshiro.lg.jp/kanko/hito/iinoya.html|title=井伊谷・井伊家と新城地域|publisher=新城市|access-date=2023-02-26}} The Iinoya trio were powerful clans that originated from the eastern side of Mikawa who greatly contributed to Ieyasu's expansion during his conquest of the former Imagawa territories in Tōtōmi Province.{{cite web |author1=Watanabe Daimon |title=徳川家康を遠江で手引きした「井伊谷三人衆」とは、いったい何者なのか |url=https://news.yahoo.co.jp/expert/articles/f996f723c6f02a99afad64fa625469e8c93f47c2 |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=3 June 2024 |language=Ja |date=2023}}

In 1570, Ieyasu established Hamamatsu as the capital of his territory, placing his son Matsudaira Nobuyasu in charge of Okazaki.{{cite book|last1=Turnbull|first1=Stephen|title=Battles of the Samurai|date=1987|publisher=Arms and Armour Press|location=London|isbn=0853688265|pages=67–78}}{{efn|According to the Todai-ki, the castle was originally planned to be relocated to Mitsuke (the site of Kinosaki Castle is said to be), but was changed to Hamamatsu at the request of Oda Nobunaga. It is speculated that Nobunaga did not want the Oda and Tokugawa bases to be too far apart.{{harvtxt|Shiba|2021|p=190}} quoting {{cite book |last1=Koichi |first1=Abe |date=1997 |title=Shizuoka Prefecture History |chapter=Ieyasu's Conquest of Totomi and the Battle of Mikatagahara |series=General History |volume=2}}}}

{{Main|Siege of Kanegasaki (1570)|Battle of Anegawa}}

Asakura Yoshikage, the head of the Asakura clan and regent of Ashikaga Yoshiaki, refused to come to Kyōto. This caused Nobunaga to declare both of them rebels.{{Cite book |last=Sansom |first=George |title=A History of Japan, 1334–1615 |publisher=Stanford University Press |year=1961 |isbn=0804705259 |page=281}} Several reports from Mikawa Monogatari, Nobunaga Koki, Tokugawa Jikki, and a supplement from Ietada Nikki recorded that Ieyasu and his forces also participated in Oda's punitive campaign against Asakura, in which they captured Mount Tenzutsu castle. The Oda-Tokugawa forces managed to kill 1,370 enemies on April 25.

They continued the next day by besieging Kanegasaki castle.{{cite web |author1=小野 雅彦 |title=家康も撤退を知らされていなかった「金ヶ崎の退き口」 |url=https://www.rekishijin.com/27174 |website=Rekishijin |publisher=ABC ARC, inc. |access-date=10 June 2024 |language=Ja |date=2023 |quote=。織田・徳川連合軍は敵の首1370を討ち取るなどして城を攻め落とし（『家忠日記増補』）}} However the Azai clan sent reinforcements to relieve the siege so Nobunaga retreated without contacting Ieyasu. After dawn, Ieyasu withdrew from battle guided by Kinoshita Tokichi (later named Toyotomi Hideyoshi), an Oda vassal.{{cite web |author1=Koichiro Hamada (濵田 航一郎) |title=金ヶ崎合戦、姉川の戦いで徳川家康は一体どうした⁉ |url=https://www.rekishijin.com/26842 |website=Rekishijin |publisher=ABC ARC, inc. |access-date=10 June 2024 |language=Ja |date=2023 |quote=。織田・徳川連合軍は敵の首1370を討ち取るなどして城を攻め落とし（『家忠日記増補』）}}

Later, in July 1570, the brother-in-law of Nobunaga, Azai Nagamasa, who had broken his alliance with the Oda clan during the siege of Kanegasaki, and Asakura combined to fight the combined armies of Nobunaga and Ieyasu, who led 5,000 of his men to support Nobunaga at the battle.{{rp|62}} As the Oda clan engaged the Azai clan army on the right, Tokugawa's forces engaged the Asakura clan's army on the left. At first, Asakura's army gained the advantage as they steadily pushed back the Tokugawa army. However, Honda Tadakatsu suddenly launched a lone, suicidal charge,{{cite book |author1=Kazuo Kasahara (笠原一男) |title=物語日本の歴史 16: 天下びとの時代 |date=1992 |publisher=木耳社 |isbn=4839375682 |page=193 |url=https://books.rakuten.co.jp/rb/514911/ |access-date=22 May 2024 |language=Ja}} while Sakakibara Yasumasa launched his force in a timely counterattack on Asakura's flank; together they managed to beat Asakura's forces.{{Cite book |last=Turnbull |first=Stephen |title=Battles of the Samurai |publisher=Arms and Armour Press |date=1987 |isbn=0853688265 |pages=62–63}} Since Ieyasu's army was now free to move, they exploited the gap between Asakura and Azai's forces and sent Tadakatsu and Yasumasa to attack the flank of Azai's formation, which allowed the Oda-Tokugawa forces to win the battle.{{harvtxt|Stephen Turnbull |2013 |p=140}}

{{Main|Battle of Mikatagahara|Battle of Nagashino}}

In October 1571, Takeda Shingen broke the alliance with the Oda-Tokugawa forces and allied with the Odawara Hōjō clan. He decided to make a drive for Kyoto at the urging of the shōgun Ashikaga Yoshiaki, starting by invading Tokugawa lands in Tōtōmi. Takeda Shingen's first objectives in his campaign against Ieyasu were Nishikawa Castle, Yoshida Castle and Futamata Castle.

In 1572, after besieging Futamata, Shingen would press on past Futamata towards the major Tokugawa home castle at Hamamatsu. Ieyasu asked for help from Nobunaga, who sent him some 3,000 troops. Early in 1573, the two armies met at the Battle of Mikatagahara, north of Hamamatsu. The considerably larger Takeda army, under the expert direction of Shingen, overwhelmed Ieyasu's troops and caused heavy casualties. Despite his initial reluctance, Ieyasu was convinced by his generals to retreat.{{cite book|last1=Turnbull|first1=Stephen|title=The Samurai Sourcebook|date=2000|publisher=Cassell & Co|location=London|isbn=1854095234|pages=222–223}}

The battle was a major defeat, but in the interest of maintaining the appearance of a dignified withdrawal, Ieyasu brazenly ordered the men in his castle to light torches, sound drums, and leave the gates open, to properly receive the returning warriors. To the surprise and relief of the Tokugawa army, this spectacle made the Takeda generals suspicious that they were being led into a trap, so they did not besiege the castle and instead made camp for the night. This error allowed a band of Tokugawa soldiers to raid the camp in the ensuing hours, further upsetting the already disoriented Takeda army, and ultimately resulting in Shingen's decision to call off the offensive altogether. Takeda Shingen would not get another chance to advance on Hamamatsu, much less Kyoto, since he died from unknown causes shortly after the siege of Noda Castle later that same year.{{rp|153–156}}

In 1574, Shingen was succeeded by his son Takeda Katsuyori and the conflict continued as the Tokugawa forces under Honda Tadakatsu and Sakakibara Yasumasa seized many of the Takeda clan's castles,{{cite book |author1=Murata Shuzo |author2=Hattori Hideo |title=都道府県別日本の中世城館調査報告書集成 |trans-title=Collection of Japanese medieval castle survey reports by prefecture |date=2000 |publisher=東洋書林 |isbn=4887214324 |page=418 |url=https://ci.nii.ac.jp/ncid/BA49003233 |access-date=22 May 2024 |language=Ja}}{{cite book |author1=Shin Jinbutsu Ōraisha |title=歴史読本, Volume 52, Issue 3 |trans-title=History Reader, Volume 52, Masalah |date=2007 |publisher=新人物往来社 |page=92 |url=https://books.google.com/books?id=v1ozAQAAIAAJ |access-date=22 May 2024 |language=Ja}} including Komyo Castle.{{cite book |author1=煎本 増夫 |title=幕藩体制成立史の研究 |trans-title=Research on the history of the establishment of the Shogunate system |date=1979 |publisher=雄山閣出版 |page=94 |url=https://bookmeter.com/books/1502589 |access-date=15 May 2024 |language=Ja}}{{cite book |author1=Naito Family Documents Study Group |title=譜代藩の研究 : 譜代内藤藩の藩政と藩領 |trans-title=Research on the Fudai domain: the government and domain of the Fudai Naito domain |date=1972 |publisher=Meiji University |page=44 |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000001212352 |access-date=15 May 2024 |language=Ja}} At some point, Ieyasu tried to capture Inui Castle in Tōtōmi Province, but strong resistance from its garrison commander, Amano Kagehira, forced Ieyasu to abort the siege. During their retreat, Kagehira launched a counterattack to pursue Ieyasu, but this was repelled by Mizuno Tadashige and Torii Mototada, who led the rearguard.{{cite book|last=Hotta|first=Masaatsu|date=1923| title =寛政重脩諸家譜. 第2輯|publisher =國民圖書|language=Ja |page=823}}

In April 1575, Ōga Yashirō, a deputy governor of over 20 villages in Oku district of Mikawa under Matsudaira Nobuyasu, was arrested by Ōkubo Tadayo and paraded around Hamamatsu Castle. According to the investigation, Yashirō was implicated in allegations of colluding with Takeda Katsuyori to betray Ieyasu and invade the Tokugawa clan's territory. According to a letter, Yashiro had teamed up with Takeda Katsuyori of Kai to seize Okazaki Castle. However, one of Yashiro's colleagues, Yamada Hachizō, betrayed Yashiro and passed this information to Nobuyasu. Meanwhile, Ieyasu himself also learned about Yashirō's further crimes of corruption in governance through a vassal's report.{{cite web |author1=Hamada Kōichirō (濱田浩一郎) |title=「どうする家康」『徳川実紀』が描く大岡弥四郎事件 岡崎クーデターはなぜ失敗したのか？ |trans-title="What would you do, Ieyasu?" The Ōga Yashirō Incident as described in the Tokugawa Jikki: Why did the Okazaki Coup fail? |url=https://sengoku-his.com/694 |website=Rekishijin |publisher=Abc Arc, inc. |access-date=9 June 2024 |language=Ja |date=2023}} Yashirō was then executed by being mutilated alive with a saw, while Tadayo crucified his wife and children.{{cite web |author1=Watanabe Daimon |title=残酷すぎて放映できなかった、大岡弥四郎のあまりにむごたらしい最期 |url=https://news.yahoo.co.jp/expert/articles/df6862aa19e2d4a45354f63f4cd6a4c22a740cfc |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=4 June 2024 |language=Ja}}

In June, during Takeda Katsuyori's raid on Mikawa Province when he attacked Yoshida Castle and besieged Nagashino Castle, Ieyasu appealed to Nobunaga for help; Nobunaga came personally with 30,000 men. The Oda-Tokugawa forces 38,000 strong won a great victory and successfully defended Nagashino Castle. Though the Takeda forces had been destroyed, Katsuyori survived the battle and retreated to Kai Province.{{Cite book|last=Turnbull|first=Stephen|url=https://books.google.com/books?id=savvCwAAQBAJ&q=temple+on+the+road+back+towards+kai|title=Nagashino 1575: Slaughter at the barricades|date=2012|publisher=Bloomsbury Publishing|isbn=978-1-78200-229-1|pages=79|language=en}} For the next seven years, Ieyasu and Katsuyori fought a series of small battles through which Ieyasu's troops managed to wrest control of Suruga Province from the Takeda clan.

File:築山殿.jpg

In 1579, Lady Tsukiyama, Ieyasu's wife, and his heir Matsudaira Nobuyasu were accused by Nobunaga of conspiring with Takeda Katsuyori to assassinate Nobunaga, whose daughter Tokuhime was married to Nobuyasu. Ieyasu ordered his wife to be executed and forced his son to commit seppuku because of these accusations.{{cite book |author1=Cecilia Segawa Seigle |author2=Linda H. Chance |title=Ōoku The Secret World of the Shogun's Women |date=2014 |publisher=Cambria Press |isbn=9781604978728 |url=https://books.google.com/books?id=nbF5CgAAQBAJ |access-date=6 May 2024 |language=En |quote=Notes 23= Tsukiyama-Dono pp. 85–86; Kinseishi p. 30}}{{cite book |author1=Arthur Lindsay Sadler |author1-link=Arthur Lindsay Sadler |title=Shogun The Life of Tokugawa Ieyasu |date=2004 |publisher=Tuttle Publishing |isbn=9781462916542 |page=53 |url=https://books.google.com/books?id=5HhzBgAAQBAJ |access-date=6 May 2024 |language=En}}

There are various theories regarding this incident. According to the "Mikawa Monogatari'", which was written by Ōkubo Tadachika, Tokuhime, wife of Nobuyasu, who was not on good terms with her mother-in-law Tsukiyama-dono, wrote in a letter to her father, Nobunaga, that her mother-in-law and her husband were secretly conspiring with Takeda Katsuyori.{{harvtxt|Tetsuo Owada|2002|p=24}}

However, this hypothesis has been considered implausible by various historians in the modern era. According to Katsuhiro Taniguchi, the more plausible theory was that there was friction within the house of Tokugawa clan between two factions with conflicting ideals, as proposed by the writer Tenkyu Goro. One faction, dubbed the "Hamamatsu Castle Faction," was active on the front lines and had many opportunities to advance their careers. The other faction was the "Okazaki Castle Faction," which consisted of Tokugawa vassals responsible for logistical support due to past injuries and other factors that caused them to play a lesser role in the politics of Tokugawa clan. According to this theory, the conflict between these two factions eventually led to a conflict between Ieyasu, representing the Hamamatsu faction, and his son Nobuyasu, representing the Okazaki faction, finally ending with Nobuyasu's death in prison. Nobuyasu planned to exile Ieyasu with the help of the Okazaki Castle faction. Before and after his son's execution, Ieyasu punished or executed many of those who worked at Okazaki Castle, although some escaped. Taniguchi theorized that Tsukiyama also participated in the coup d'état that was going on in Okazaki Castle.{{sfn|Taniguchi|2007|pp=209–211}} Furthermore, Sakai Tadatsugu, the most prominent general of Ieyasu, also may have played a role in confirming Oda Nobunaga's suspicion of the alleged betrayal against the Oda clan being planned by Nobuyasu Tsukiyama. Ieyasu may have concluded that if a high-ranking fudai daimyō such as Tadatsugu had confirmed the accusations against Lady Tsukiyama, then they must be true.

Another theory has said that Tadatsugu was actually conspiring with the Ieyasu's mother, Odai no Kata, to get rid of Lady Tsukiyama. Arthur Lindsay Sadler theorized this was a deliberate act of spite from Tadatsugu due to many senior Tokugawa clan generals' dislike of Nobuyasu.

In the same year, Ieyasu named his third son, Tokugawa Hidetada, as his heir, since his second son had been adopted by Toyotomi Hideyoshi, who would later become a powerful daimyo.{{Citation needed|date=March 2020}}

{{Main|Siege of Takatenjin (1581)|Battle of Tenmokuzan}}

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|text=Positions of the Takatenjin Castle and the six forts
1.Ogasayama Fort, 2.Nogasaka Fort, 3.Higamine Fort,4. Shishigahana Fort, 5.Nakamura Fort, 6.'Mitsuiyama Fort, 7.Takatenjin Castle}}

In 1580, Ieyasu built five fortresses in order to isolate Takatenjin Castle from external supplies and reinforcements.{{cite web |title=高天神城と六砦 |trans-title=Takatenjin Castle and Six Fortresses |url=https://www.city.kakegawa.shizuoka.jp/gyosei/docs/8327.html |website=city.kakegawa.shizuoka.jp |publisher=Kakegawa City |access-date=28 May 2024 |location=Kakegawa City, Shizuoka |language=Ja |date=2019}}{{cite web |author1=Mizuno Shigeru |title=大坂砦 |trans-title=Osaka Fort |url=https://www.sankei.com/article/20150920-IA4VDCQT2NJMTK727CAET3RULA/ |website=sankei.com |publisher=The Sankei Shimbun |access-date=28 May 2024 |language=Ja |date=2015}}{{cite web |author1=Mizuno Shigeru |title=小笠山砦 |trans-title=Ogasayama Fort |url=https://www.sankei.com/article/20150927-IXWVQDD66VJKFKVXKYU53TIRAU/ |website=sankei.com |publisher=The Sankei Shimbun |access-date=28 May 2024 |language=Ja |date=2015}} In addition to those five new fortresses, Ieyasu renovated an old castle named Ogasayama fort, which had originally been built by Ieyasu far before the conquest of Tōtōmi Province against Imagawa clan to capture Kakegawa Castle. With the six fortresses, which were referred to as the "six fortresses of Takatenjin", completed, Ieyasu assigned Ishikawa Yasumichi to the Ogasayama fort, Honda Yasushige to the Nogasaka fort, Osuga Yasutaka to the Higamine, Shishigahana,{{cite web |title=獅子ヶ鼻砦跡 |trans-title=Shishigahana Fort Ruins |url=https://www.city.kikugawa.shizuoka.jp/shoukoukankou/shishigahana.html |website=city.kikugawa.shizuoka.jp |publisher=Kikugawa City |access-date=28 May 2024 |date=2022}} and Nakamura forts, while Sakai Ietada was appointed to garrison the Mitsuiyama fort.

The Takatenjin castle which was defended by Okabe Motonobu, immediately suffered from a period of starvation as the siege by Oda-Tokugawa forces intensified. In response, Motonobu tried to negotiate a truce with Ieyasu by offering Takisakai and Koyama Castle in exchange for Takatenjin castle being spared from the siege.{{Cite book |author = Marushima Kazuhiro |title = 武田勝頼 |series = 中世から近世へ |publisher = 平凡社|date = 2017}} After Ieyasu consulted with Nobunaga on this matter, he refused Motonobu's plea. Nobunaga stated his reason in a letter saying that if Takeda Katsuyori sent his forces to assist Motonobu, then there would be an opportunity to bait the Takeda army into coming outside the castle and annihilate them on the field. Meanwhile, Nobunaga also stated that if Katsuyori neglected helping Motonobu at all, it would damage the Takeda clan's credibility because they could not save their own vassals.{{cite book |author1=Okuno Takahiro |title=増訂 織田信長文書の研究 上巻 |trans-title=Expanded study of Oda Nobunaga's documents, Volume 1 |date=2007 |publisher=吉川弘文館 |isbn=9784642009072 |url=https://www.yoshikawa-k.co.jp/book/b77694.html |access-date=28 May 2024 |language=Ja}}

In 1581, Ieyasu forces managed to subdue Tanaka castle,{{cite book |title=ð̇Æ̇̌Þ̄ʹđ̇: Rekicho yoki |date=1998 |page=九日圍:田中城、井伊直政歲十八 |publisher=Æ̇̌Þ̄ʹđ̇ʺ̇·ð̇ỡ |url=https://books.google.com/books?id=7JwJAQAAMAAJ |access-date=19 May 2024 |language=Ja}}{{cite book |author1=Kajiwara Ai |author2=Matsudaira Yoriyasu |date=2003 |publisher=神道大系編纂会 |title=田中城、井伊直政歲十八 |url=https://books.google.com/books?id=R0EyAQAAIAAJ |access-date=19 May 2024 |language=Ja}}{{cite book |author1=Kimura Takaatsu |title=武徳編年集成 |date=1976 |publisher=名著出版 |page=229 |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000001222955 |access-date=19 May 2024 |language=Ja}}{{cite book |author1=Motonao Narushima |author2=Tadachika Kuwata |author3=Takehisa Udagawa |title=改正三河後風土記 Volume 2 |trans-title=Revised Mikawa Go Fudoki Volume 2 |date=1976 |publisher=秋田書店 |page=110 |language=Ja}} and recapture Takatenjin castle, where Okabe Motonobu was killed during the fight.{{cite web|url=https://kotobank.jp/word/%E5%B2%A1%E9%83%A8%E9%95%B7%E6%95%99-1062236|title=デジタル版 日本人名大辞典+Plus「岡部長教」の解説|publisher=kotobank|access-date=20 October 2021}}

The end of the war with Takeda Katsuyori came in 1582, when a combined Oda-Tokugawa force attacked and conquered Kai Province, where Katsuyori was cornered and defeated at the Battle of Tenmokuzan, and then committed seppuku.{{sfn|Turnbull |1998 |p=231}} With the Takeda clan practically annihilated as political entity, Nobunaga gave Ieyasu the right to govern Suruga Province in recognition of his service in the fight against the Takeda clan.{{cite web |author1=Susumu Shimazaki (島崎晋)|author2=Rekishijin Editorial Department |title=徳川家康が武田氏を倒したとき、織田信長が褒美にくれた領地は広かった！ |trans-title=When Tokugawa Ieyasu defeated the Takeda clan, the territory that Oda Nobunaga gave him as a reward was vast! |url=https://www.rekishijin.com/26846 |website=Rekishijin |publisher=ABC ARC, Inc. |access-date=24 June 2024 |language=Ja |date=2023 |quote=From 'The Truth About Tokugawa Ieyasu' in the February 2023 issue of Rekishijin article}}

{{Main|Honnō-ji Incident}}

In late June 1582, before the incident at Honnō-ji temple, Oda Nobunaga invited Ieyasu to tour the Kansai region in celebration of the demise of the Takeda clan. Before the meeting could take place, Ieyasu learned that Nobunaga had killed himself at Honnō-ji temple after being surrounded and overwhelmed by the forces of Akechi Mitsuhide.

When Ieyasu heard that Nobunaga had been killed by Akechi Mitsuhide he had only a few companions with him, notably Sakai Tadatsugu, Ii Naomasa, and Honda Tadakatsu, Sakakibara Yasumasa and some others.{{rp|314–315}}{{cite book |author1=Fumitaka Kawasaki |url=https://books.google.com/books?id=9nNNAAAAMAAJ |title=徳川家康・伊賀越えの危難 |date=1985 |publisher=鳥影社 |isbn=4795251126 |trans-title=Tokugawa Ieyasu and the danger of crossing Iga |access-date=24 May 2024}} The Iga provincial route was dangerous because of the Ochimusha-gari, or "Samurai hunters" gangs.{{efn|During the Sengoku period, particularly dangerous groups called "Ochimusha-gari" or "fallen warrior hunter" groups had emerged. These groups consisted of peasants or rōnin who had been dispossessed by war and now formed self-defense forces which operated outside the law, while in reality they often resorted to hunting and robbing defeated Samurai or soldiers during conflicts.{{cite book |author1=Fujiki Hisashi |title=刀狩り: 武器を封印した民衆 |date=2005 |publisher=岩波書店 |isbn=4004309654 |pages=29–30 |language=Ja |quote=Kunio Yanagita “History of Japanese Farmers”}}{{cite book |author1=Kirino Sakuto |title=真説本能寺 (学研M文庫 R き 2–2) |date=2001 |publisher=学研プラス |isbn=4059010421 |pages=218–219 |language=Ja |quote=Tadashi Ishikawa quote}}{{Cite book|author= Akira Imatani |date= 1993 |pages=152–153, 157–158, 167 |quote=Akira Imatani“Practice of attacking fallen warriors”; 2000; p. 153 chapter 4 |title=天皇と天下人|publisher=新人物往来社|isbn=4404020732}} These outlaw groups were particularly rampant on the route which Ieyasu taken to return to Mikawa.}} Ieyasu and his party, therefore, chose the shortest route back to Mikawa Province by crossing Iga Province. The exact route differs in many versions according to primary sources Tokugawa Nikki or Mikawa Todai-Hon:

• The Tokugawa Nikki theory stated that Ieyasu took the roads to Shijonawate and Son'enji, then followed the Kizu River until they spent a night in the Yamaguchi Castle. The next day they reached a stronghold of the Kōka ikki clan branch from Tarao who allowed them to take refuge for the night. On the last day, Ieyasu's group used a ship from Shiroko to reach Okazaki Castle.{{cite book |author1=Yamada Yuji |translator=Atsuko Oda |title=The Ninja Book : The New Mansenshukai |date=2017 |publisher=Mie University Faculty of Humanities, Law and Economics |url=https://books.google.com/books?id=2FwUDgAAQBAJ |access-date=10 May 2024 |language=En |chapter=7. Tokugawa Ieyasu's passing through Iga}} However, The Tokugawa Nikki theory is doubted by modern historians, since it was not the shortest route for Ieyasu to reach Mikawa from his starting position in Sakai,{{Cite web |author=Masahiko Iwasawa |date=1968 |title=家忠日記の原本について |trans-title=(Editorial) Regarding the original of Ietada's diary |url=https://www.hi.u-tokyo.ac.jp/publication/syoho/02/syoho0002-iwazawa.pdf |access-date=2022-11-16 |website=東京大学史料編纂所報第２号 |language=ja}} and it was considered by historical researchers to be a very risky path due to the existence of Iga ikki clans which were hostile to the Oda and Tokugawa clans.{{cite book |title=(みちものがたり)家康の「伊賀越え」（滋賀県、三重県）本当は「甲賀越え」だった?忍者の末裔が唱える新説 |trans-title=(Michi-monogatari) Ieyasu's "Iga's crossing (Shiga Prefecture, Mie Prefecture) Was it really "Koka-goe"? A new theory advocated by a ninja descendant |date=2020 |publisher=Asahi Shimbun |url=https://www.asahi.com/articles/DA3S14509491.html |access-date=19 May 2024 |language=Ja}}

• The Mikawa Toda-Hon theory stated that Ieyasu went north from Ogawadate, crossed Koka, and entered Seishu Seki (from Shigaraki), passing through Aburahi and entering Tsuge in Iga. This theory was championed by modern Japanese historians such as Tatsuo Fujita from Mie University, who took this material to formulate three different theories about the details of Ieyasu's trek.{{cite web |author1=Tatsuo Fujita |title=Lecture No.1: Fact about "Shinkun Iga Goe" (1st Term) : Fact about "Shinkun Iga Goe" (1st Term) (summary) |url=https://www.human.mie-u.ac.jp/en/projects/iga/lecture/2015/2015-1.html |website=Faculty of Humanities, Law and Economics & Graduate School of Humanities and Social Sciences |access-date=6 June 2024 |language=En}} This theory is also supported by a group of historical researchers from Mie city, who happened to be descendants of the Kōka ikki clans. The researchers stated that by taking this path, before Ieyasu's group reached Kada pass where they could be escorted by the Kōka clan Jizamurai, Ieyasu mostly depended on the protection of his high-rank vassals, particularly the four Shitennō generals of the Tokugawa clan, rather than the popular theory about getting help from the "Iga Ninja" clans.

File:国道25号.jpg

Regardless which theory was true, historians agreed that when his path ended at Kada (a mountain pass between Kameyama and Iga), the Tokugawa group suffered one last attack by Ochimusha-gari outlaws as they reached the territory of Kōka ikki clans of Jizamurai who were friendly to the Tokugawa clan. The Koka ikki samurais assisted Ieyasu in eliminating the threat of the Ochimusha-gari outlaws and escorted them until they reached Iga Province, where they were further protected by other allied clans from Iga ikki who accompanied Ieyasu and his group until they safely reached Mikawa.

Portuguese missionary Luís Fróis recorded in his work History of Japan that during this journey, Tokugawa retainers including Sakai Tadatsugu, Ii Naomasa and Honda Tadakatsu fought their way out of raids and harassment from Ochimusha-gari outlaws while escorting Ieyasu, while paying bribes of gold and silver to those Ochimusha-gari outlaws that could be bribed.{{cite book |author1=Mitsuhisa Takayanagi |title=戦国戦記本能寺の変・山崎の戦 (1958年) |date=1958 |publisher=春秋社 |page=65 |url=https://ndlsearch.ndl.go.jp/books/R100000039-I2973958 |access-date=9 May 2024 |language=Ja |quote=Luís Fróis;History of Japan..; Nihon Yoso-kai Annual Report”, Japanese historical materials also show that Ieyasu distributed a large amount of gold and silver to his subordinates) A certain “ Ishikawa Tadashi Sosho}} Matsudaira Ietada recorded in his journal, Ietada nikki (家忠日記), the Ieyasu's escorts suffered around 200 casualties during their journey, and when they arrived at Ietada's residence in Mikawa, they only had about 34 personnel left, including high-ranking Tokugawa generals including Tadatsugu, Naomasa, Tadakatsu, Sakakibara, Ōkubo Tadayo, Hattori Hanzō, and others.{{Cite web|url= https://www.hi.u-tokyo.ac.jp/publication/syoho/02/syoho0002-iwazawa.pdf |title=(Editorial) Regarding the original of Ietada's diary |author= Masahiko Iwasawa |website= 東京大学史料編纂所報第２号 |date=1968 |access-date= 2022-11-16 }}{{Cite book|author=Morimoto Masahiro |url=https://www.amazon.co.jp/%E5%AE%B6%E5%BA%B7%E5%AE%B6%E8%87%A3%E3%81%AE%E6%88%A6%E3%81%A8%E6%97%A5%E5%B8%B8-%E6%9D%BE%E5%B9%B3%E5%AE%B6%E5%BF%A0%E6%97%A5%E8%A8%98%E3%82%92%E3%82%88%E3%82%80-%E8%A7%92%E5%B7%9D%E3%82%BD%E3%83%95%E3%82%A3%E3%82%A2%E6%96%87%E5%BA%AB-%E7%9B%9B%E6%9C%AC-%E6%98%8C%E5%BA%83-ebook/dp/B0BHL5SPG3|title=

家康家臣の戦と日常 松平家忠日記をよむ (角川ソフィア文庫) Kindle Edition|publisher=Kadokawa |date=1999|access-date=10 May 2024}}

{{Infobox military conflict

|conflict = Tenshō-Jingo war

|partof = Sengoku period

|image = Wakamiko castle 01.jpg

|caption = Ruins of Wakamiko castle, base of Hōjō army during the conflict{{cite web |title=徳川対北条"天正壬午の乱"甲斐の覇権の行方は？北条軍の本陣跡「若神子城」|trans-title=Tokugawa vs. Hojo "Tensho Jingo Rebellion" - What will become of Kai's hegemony? Hojo army's main camp site "Wakamiko Castle" |url=https://favoriteslibrary-castletour.com/yamanashi-wakamikojo/ |website=夢中図書館 いざ城ぶら！ |access-date=14 July 2024 |language=Ja |date=2024}}

|date = June - October 29, 1582

|place = Kai Province, Shinano Province, Kōzuke Province, Izu Province

|result = Truce between Tokugawa and Hōjō clan
Tokugawa clan gains significant portions of Kai and Shinano provinces
Uesugi clan withdrawn from the conflict

|combatant1 = Hōjō clan 15px
Satomi clan 15px

|combatant2 = Tokugawa clan 15px

|combatant3 = Uesugi clan 15px

|commander1 = Hōjō Ujinao
Hōjō Ujikatsu
Satomi Yoshiyori
Daidōji Masashige
Hoshina Masatoshi (defected to Tokugawa)
Hoshina Masanao (defected to Tokugawa)
Kiso Yoshimasa (defected to Tokugawa)

|commander2 = Tokugawa Ieyasu
Sakai Tadatsugu
Torii Mototada
Yoda Nobushige
Sone Masatada
Okabe Masatsuna
Ii Naomasa
Ōkubo Tadayo
Sakakibara Yasumasa
Mizuno Katsunari
Hattori Hanzō

|commander3 = Uesugi Kagekatsu
Ogasawara Dōsetsusai
Sanada Masayuki (defected to Hōjō side, but then defected again to Tokugawa side)

|strength1 = 55,000 (Hōjō army)
10,000 (Satomi army)

|strength2 = 8,000 (Tokugawa army)
3,800-3,900 (Former Takeda clan warriors)

|strength3 = Unknown

|casualties1 =

|casualties2 =

|casualties3 = Unknown

}}

After Ieyasu reached Mikawa, he immediately moved to shift his focus to former Takeda clan territory as he expected unrest there. As a preemptive measure, Ieyasu dispatched Honda Nobutoshi to contact Kawajiri Hidetaka, who ruled Suwa District as a vassal of the Oda clan, to request cooperation.{{sfn|Hirayama|2015|p=127}}

Meanwhile, Ieyasu had Yoda Nobushige, the former Takeda clan governor of the Saku district who had been hidden in the Tokugawa territory and had maintained contact with Ieyasu, organize contacts with the other remaining vassals of the Takeda clan to restore order in the chaos following the death of Nobunaga.{{sfn|Hirayama|2015|p=127}} At that moment, Nobushige was settled in the secluded village of Osawa.{{cite web |author1=Matsuzaki Town Office, Planning and Tourism Division |title=依田家 |trans-title=Yoda clan |url=https://www.town.matsuzaki.shizuoka.jp/docs/2016020300202/ |website=花とロマンの里 松崎町 |publisher=Matsuzaki Town |access-date=6 June 2024 |language=Ja |date=2015}} At the same time, Uesugi and the Hōjō clans also mobilized their forces to invade Shinano Province, Kōzuke Province, and Kai Province (currently Gunma Prefecture), which were ruled by the remnants of the many small clans that formerly served the Takeda clan, when they learned of the death of Nobunaga. This caused a triangular conflict between those three factions known as the {{Nihongo|Tenshō-Jingo War|天正壬午の乱|Tenshō-Jingo no ran}}.{{efn|The name of "Tenshō-Jingo War" was coined by Tashiro Takashi in 1980.{{cite book |author1=Okamoto Ryoichi (岡本亮一) |title=日本城郭史研究叢書 第8巻 大坂城の諸研究 |trans-title=Japanese Castle History Research Series Vol. 8 Various Studies on Osaka Castle |date=1982 |publisher=名著出版 |isbn=4404010362 |pages=412–413 |url=https://www.kosho.or.jp/products/detail.php?product_id=445990645 |access-date=6 June 2024 |language=Ja}} Furthermore, there is also a theory that from the perspective that local powers which continued to fight over the possession of the Oda clan's leftover territories, there is evidence that Tokugawa Ieyasu's transfer to the Kantō region following the fall of the Hōjō clan in 1590 and the placement of Toyotomi-line daimyo, until transfer of Uesugi Kagekatsu to Aizu, where the local daimyo were separated from their former territory and the establishment of control by the Azuchi–Momoyama period, was considered to be the extension of this conflict.{{harvtxt|Okamoto Ryoichi (岡本亮一) |1982 |pp=41–42}}}}{{cite book |author1=Masaru Hirayama (平山優) |title=能見城跡 |trans-title=Nomi Castle Ruins |publisher=韮崎市教育委員会 {{!}} 韮崎市遺跡調査会 {{!}} 東京電力株式会社山梨支店 |year=1998 |pages=14–39 |url=https://doi.org/10.24484/sitereports.6772-6247 |access-date=14 July 2024 |language=Ja |chapter=天正壬午の乱 信長死後の旧武田領争奪戦について / The Tensho Jingu Rebellion: The struggle for the former Takeda territory after Nobunaga's death|doi=10.24484/sitereports.6772-6247 }}{{cite book |author1=Miyakawa Nobuo (展夫宮川) |title=天正壬午の乱と北関東 |work=国立国会図書館サーチ（NDLサーチ） |trans-title=The Tensho Jingo Rebellion and Northern Kanto |year=2010 |publisher=Komazawa University History faculty |pages=50–63 |url=https://ndlsearch.ndl.go.jp/books/R000000025-I012470004016261#bib |access-date=14 July 2024 |language=Ja}}{{cite book |author1=Tetsuo Owada |author1-link=Tetsuo Owada |year=2023 |title=最大の危機から五ケ国の大大名へ : 飛躍を支えたもの (特集 伊賀越え、天正壬午の乱… 徳川家康と本能寺の変 : その時、何が起きたか) |trans-title=From the greatest crisis to becoming a great feudal lord of five provinces: What supported the leap (Special feature: Crossing Iga, the Tensho Jingo War... Tokugawa Ieyasu and the Honnoji Incident: What happened then?) |publisher=歴史街道 |pages=14–20 |url=https://ndlsearch.ndl.go.jp/books/R000000004-I032912074#bib |access-date=14 July 2024 |language=Ja}}{{cite book |author1=Hiraku Kaneko (金子拓) |year=2023 |title=競うように接待しあう家康と信長…本能寺直前に何があったか (特集 伊賀越え、天正壬午の乱… 徳川家康と本能寺の変 : その時、何が起きたか)|trans-title=Ieyasu and Nobunaga competed to entertain each other... What happened just before the Honnoji Incident? (Special feature: Crossing Iga, Tensho Jingo War... Tokugawa Ieyasu and the Honnoji Incident: What happened then?) |publisher=歴史街道 |pages=24–29 |url=https://ndlsearch.ndl.go.jp/books/R000000004-I032912077 |access-date=14 July 2024 |language=Ja}}

At first, the Hōjō clan, who ruled the Kantō region, led an army of 55,000 men to invade the Shinano Province through Usui,{{cite web |author1=Masaru Hirayama |title=天正壬午の乱【増補改訂版】─本能寺の変と東国戦国史 |trans-title=Tensho Migo Rebellion [revised and enlarged edition] - Honnoji Incident and the history of the Sengoku period in the Togoku region |url=https://sengokumap.net/history/1582-4/ |publisher=Ebisukosyo |access-date=17 May 2024 |language=Ja |date=2016}} as they aimed to prevent a Tokugawa incursion of Kai.{{cite web |author1=Susumu Shimazaki (島崎晋) |author2=Rekishijin Editorial Department |title=徳川家康の願い「信長亡き今、東国を渡してはならない！」─天正壬午の乱とは？─ |trans-title=Tokugawa Ieyasu's wish: "Now that Nobunaga is dead, the eastern provinces must not be handed over to us!" - What was the Tensho Jingo Rebellion? - |url=https://www.rekishijin.com/26848 |website=Rekishijin |publisher=ABC ARC, inc. |access-date=24 June 2024 |language=Ja |date=2023 |quote=From "The Truth About Tokugawa Ieyasu" in the February 2023 issue of Rekishijin article}} By June 13, 1582, the Hōjō clan had captured Iwadono Castle in Tsuru District and instructed Watanabe Shozaemon, a local magistrate from the Tsuru District, to assist them in their conquest.{{sfn|Hirayama|2015|pp=132-133}} Subsequently, Sanada Masayuki led his army and captured the Numata Castle for the Uesugi clan.{{sfn|Hirayama|2015|pp=91–97}}

On June 14 however, Kawajiri Hidetaka killed Honda Nobutoshi. This was followed by an uprising from many of the clans in Kai province against Hidetaka the following day, which resulted in Hidetaka being killed on June 18.{{sfn|Hirayama|2015|pp=63}} The Hōjō also gained support from the Hoshina clan, which was a former Takeda vassal, led by Hoshina Masatoshi and his sons Hoshina Masanao and Naitō Masaaki.{{sfn|Hirayama|2015|p="Hoshina Masatoshi" chapter}} By the end of June, they had secured all of the territory except for the areas controlled by the Sanada in Numata and Agatsuma.

Meanwhile, Ieyasu immediately marched his 8,000 soldiers to the disputed regions and then split his army into two parts, with the separate detachment led by Sakai Tadatsugu and Ogasawara Nobumine going to pacify the Shinano Province, while Ieyasu took the main force to pacify Kai. Tadatsugu and Nobumine met with unexpected resistance from Suwa Yoritada, a former Takeda vassal who was now allied with the Hōjō clan.{{Citation|author1=Abe takeshi|author2=Abe takeshi |trans-title=Encyclopedia of Famous People from the Sengoku Period |title=戦国人名事典|edition=コンパクト|publisher=新人物往来社 |date=1990|isbn=4404017529 |page=440}} They were beaten by Yoritada, who were then reinforced by the Hōjō clan, forcing Tadatsugu to retreat. As Tadatsugu's forces retreated, they were pursued by 43,000 men of the Hōjō clan army. Okabe Masatsuna, a member of the Suruga clan samurai who once served under Baba Nobuharu, took the initiative to defend the rear of Tadatsugu's army from the enemy charges and repelled them. As they successfully retreated without further losses, they rejoined Ieyasu's main forces in the area of Wakamiko in Suwamachi (modern day Yamanashi Prefecture).

On June 5, Ieyasu instructed Orii Tsugumasa and Yonekura Tadatsugu, two members of Takekawa clan from Kai who were hiding in Kiriyama, Tōtōmi Province, to proceed with the work of enticing the Kai samurai to the Tokugawa side. The next day, Ieyasu also sent a letter to Masatsuna instructing him to begin the construction of a castle at Shimoyama, Minobu Town in the Kai Kawachi domain, the former base of Anayama Nobutada, one of Tokugawa's retainers who was killed by outlaws during his escape after the Honnō-ji Incident. Suganuma Castle (Terazawa, Minobu Town) was built along the Fuji River and the Suruga Highway (Kawachi Road). After the death of Nobutada and the senior members of the Obikane clan, to which they had pledged loyalty, the Anayama clan was left leaderless, so they decided to pledge allegiance to Ieyasu.{{sfn|Hirayama|2015|pp=126–127}}

Ieyasu then dispatched Sone Masatada, formerly one of Shingen Takeda's three most prominent generals,{{efn|the other two were said to be Yamagata Masakage and Sanada Masayuki.}} to the Erinji area with 500 men to confront a Hōjō force that numbered 3,000 men. Masatada managed to defeat them and inflicted between 600 and 700 casualties. On June 12, Masatada joined forces with another former Takeda vassal, Okabe Masatsuna,{{cite web |author1=Wada Yasuhiro (和田裕弘) |title=曽根昌世、岡部正綱、依田信蕃、下条頼安～「天正壬午の乱」で徳川家康の窮地を救った人々 |trans-title=Masayo Sone, Masatsuna Okabe, Nobutaka Yoda, Yorian Shimojo - People who saved Tokugawa Ieyasu from a difficult situation during the Tensho Jingo war |url=https://rekishikaido.php.co.jp/detail/10528 |website=rekishikaido |publisher=PHPオンライン |pages=1–2 |access-date=11 June 2024 |language=Ja |date=2023}} and a senior Tokugawa general, Osuga Yasutaka.{{cite book |author1=Sakai Yōko |year=1999 |title=家康家臣団における大須賀康高の役割 |trans-title=The Role of Yasutaka Osuga among Ieyasu's Retainers |series=日本歴史 No.612 |publisher=日本歴史学会 編 |pages=59–77 |url=https://ndlsearch.ndl.go.jp/books/R000000004-I4712510 |access-date=14 July 2024 |language=Ja}} The same day, Yoda Nobushige set off to Saku District and rallied around 3,000 Takeda clan retainers as Ieyasu instructed.{{sfn|Hirayama|2015|p=128}}

Several days later, Osuga Yasutaka, a senior Tokugawa vassal, inspected Masatada's troops, where he commended the cooperation of Masatada lieutenant, Kubota Masakatsu. Later on June 28, Ieyasu also dispatched the Anayama clan to resist the Hōjō clan. He also sent his generals Ōkubo Tadayo, Ishikawa Yasumichi and Honda Hirotaka along with his son Yasushige as reinforcements for them to resist the Hōjō.{{sfn|Hirayama|2015|pp=132–133}}

At some point during this war, the Tokugawa clan also gained support from the Tomohisa clan.{{efn|The Tomohisa clan was a powerful clan that ruled the Ryuto area (left bank of the Tenryu River) in Shimoina during the medieval era. They were originally from Chikuzawa (modern day Minowa Town, Kamiina District, Nagano) and were said to be one of the branches of the Suwa clan. During the Tensho-Jingo war, the Tomohisa was the ruler of Chikudaira Castle, located in Chikudaira, Shimo-Kuken, Iida City.{{cite web |title=知久平城跡（ちくだいらじょうあと） 1区域 |trans-title=Chikudaira Castle Ruins: Area 1 |url=https://www.city.iida.lg.jp/site/bunkazai/chikudairajo.html |website=飯田市ホームページ |publisher=Iida City |access-date=14 July 2024 |language=Ja |year=2024}} Reference:

• "Chikuhira Castle Ruins" by Ichimura Kanjin, 1935, "Report on the Survey of Historical Sites, Places of Scenic Beauty and Natural Monuments", Vol. 20
• Exhibition report for "First public exhibition of castle maps of Nagano prefecture" by Michiharu Tomihara, Director of the Shirohaku Museum of Old Maps and Castles, Tomihara Bunko 2012　
• "Chiku Heijo" by Kiyoto Hirazawa, 1965, Ina, December 1965 issue, Ina Historical Society
• "The Tokugawa daimyo's control over their territories during the Sengoku and Oda-Toyotomi periods" Hiroyuki Shiba 2014
• "History of Iida and Kamiiida, Vol. 1" Iida City Board of Education 2012
• "The Tensho Jingo Rebellion" Hirayama Masaru 2011
• Shimo-Kukata Village Journal Shimo-Kukata Village Journal Publishing Association 1973}}

Uesugi Kagekatsu of the Uesugi clan also made his move by supporting former Takeda clan forces under the leadership of Ogasawara Dōsetsusai from the Ogasawara clan and Yashiro Hidemasa at Chikuma and the Nishina clan of Azumino. They defeated and expelled Kiso Yoshimasa, who had been granted the control of both Chikuma and Azumino by Oda Nobunaga.{{sfn|Hirayama|2015|p=167}} They then faced another branch of Ogasawara clan which was led by Ogasawara Sadayoshi and his retainers which opposed the steps taken by Dōsetsusai. Sadayoshi's group appealed to the Tokugawa clan and offered their allegiance to Ieyasu.{{sfn|Hirayama|2015|p=188}} On June 24, Kagekatsu advanced into northern Shinano and entered Naganuma castle.{{sfn|Shinichi |2005|p=33}}

As the triangular battle was underway between the three factions, order was restored in Owari province as the rebellion of Akechi Mitsuhide had already been suppressed in the Battle of Yamazaki. Ieyasu also informed the Oda clan of the developments in Shinano and Kai.{{sfn|Hirayama|2015|pp=82, 124, 126}} In response, on July 7, as the Oda clan learned of the defeat of Takigawa Kazumasu by the Hōjō clan at the Battle of Kanagawa, Toyotomi Hideyoshi sent a letter to Ieyasu to give him authorization to lead military operations to secure the two provinces of Kai and Shinano from the Hōjō and Uesugi clans.{{efn|Ieyasu's position and actions here are not those of an independent feudal lord, but as a feudal lord under the Oda regime, with the aim of defeating the Hojo clan {{Cite journal|author=Miyagawa Nobuo |date=2012|title=天正期北関東政治史の一齣 : 徳川・羽柴両氏との関係を中心に |trans-title=A Scene in the Political History of Northern Kanto during the Tensho Period: Focusing on the Relationship with the Tokugawa and Hashiba Clan|url=http://repo.komazawa-u.ac.jp/opac/repository/all/32738/|journal=駒沢史学|issue=78|pages=19–37|publisher=駒沢史学会|issn=0450-6928}}（Addendum: Kazuhiro Marushima (丸島和洋), 2011, page 4）}}

File:Komoro castle00s3872.jpg

Ieyasu deployed his forces to various fortresses in the Kōfu Basin to oppose Ujinao, who had camped his army in the area of present-day Hokuto City. Hattori Hanzō led Iga clan warriors to Katsuyama Castle (Kamisone-cho, Kofu City), Minakuchi Castle, and Kotohirayama Castle (Misakuchi-cho, Kofu City), where he monitored the Nakamichi road connecting Kai and Suruga.{{sfn|Hirayama|2011|pp=240–245}} Ieyasu managed to recruit more samurai clans who had formerly served under various Takeda generals such as Ichijō Nobutatsu, Yamagata Masakage, and Hara Masatane with the assistance of Ii Naomasa. Naomasa dealt with around 41 letters of submission to the Tokugawa clan.{{harvtxt|Toshikazu Komiyama |2002 |p=50～66 }}{{cite book |author1=Kōya Nakamura |author1-link=Kōya Nakamura |title=德川家康公傳 / Tokugawa Ieyasu-kō den |date=1965 |publisher=東照宮社務所 |url=https://search.worldcat.org/title/tokugawa-ieyasu-ko-den/oclc/25486453 |access-date=15 May 2024 |language=Ja}} Furthermore, Naomasa also received another letter of submission from Obata Nobusada, the leader of the Takeda clan's red armored cavalry troops.{{efn|different person than Obata Masamori Nobusada, who already died at that moment.{{cite news |author1=Fujii Takumi |title=井伊直政、新たな書状原本 25、26日に彦根で公開、講演も|trans-title=Naomasa Ii's new original letter will be released in Hikone on the 25th and 26th, and he will also give a lecture. |url=https://www.asahi.com/articles/ASRCN7J75RCBPTJB00K.html |website=asahi |publisher=The Asahi Shimbun Company |access-date=23 May 2024 |language=Ja |date=2023}}}}

On July 9, Masayuki changed his allegiance from the Uesugi to the Hōjō when he surrendered to Hōjō Ujinao,{{sfn|Shinichi|2005|p=33}} and began building a system of forifications to station his vassals in Ueno Province.{{cite web |author1=Senhish Editorial Department |title=「天正壬午の乱（1582年）」信長死後、旧武田領は戦国武将たちの草刈り場に！ |trans-title=After Nobunaga's death during the Tensho Jingo War (1582), the former Takeda territory became a battlefield for Sengoku warlords! |url=https://sengoku-his.com/453 |website=戦国ヒストリ |publisher=sengoku-his.com |access-date=11 June 2024 |language=Ja |date=2020 |quote=Masaru Hirayama, Sanada Nobushige: The Truth About the Man Called Yukimura (KADOKAWA, 2015); Hirayama Masaru, "The Tensho Jingo Rebellion: Revised and Enlarged Edition" (Ryokosho Publishing, 2015); Hirayama Masaru, "Three Generations of the Sanada" (PHP Institute, 2011)}} Subsequently, on July 12, as the troops under Hōjō Ujinao advanced across the Usui Pass, Nobushige resisted them, but then he abandoned the Komoro Castle and retreated to a fortress which he deemed more suitable to defend against the Hōjō army.{{sfn|Hirayama|2011|p=273}} Later on July 16, Sadayoshi launched an attack on Fukashi Castle, forcing Dōsetsusai along with Hidemasa to surrender.{{Cite book|title=武田氏家臣団人名辞典 |trans-title=Dictionary of the Takeda Clan's Vassals|date=2015|publisher=東京堂出版|author=Masaru Hirayama|chapter=Hoshina Masatoshi}} Ujinao advanced his troops while leaving the siege against the castle to his general, Daidōji Masashige. Meanwhile, the Hōjō negotiated a truce with the Uesugi in July 19, so they could focus their front towards the Tokugawa in Kai province, much to the dismay of Masayuki, as he had hoped to secure his territory in Numata instead of from the Uesugi.

The resistances of local warlords against Hōjō increased during this time, as an Ogasawara clan branch in Mishima Izu province under Ogasawara Hirokatsu also resisted the Hōjō clan. The Hōjō clan beat them in battle as Hirokatsu's father was killed so Hirokatsu was forced to retreat to Mitsuba Castle in Suruga province.{{Cite book|date=1964|author=Takayanagi Mitsutoshi |title=Kansei chōshū sho kafu (edited version)|volume=4|publisher=続群書類従完成会|isbn=978-4-7971-0208-6|page=63}} Meanwhile, the Enoshita clan, another local clan subject to the former Takeda clan, which was led by Enoshita Norikiyo, also showed their resistance against the Hōjō when they fought and beat a detachment of Hōjō troops at the Battle of Sakaguchi.{{cite journal |author1=Shunroku Shibatsuji |title=「武田遺臣「上野国・榎下文書」の紹介」 |trans-title="Introduction to the Takeda retainers' "Enoshita clan's documents of Kozuke Province"" |journal=Takeda Research |date=2007 |issue=37 |publisher=Takeda Research Group |language=Ja |quote=included in "Regional control of the Takeda clan territory during the Warring States period" (Iwata Shoin, 2005)}}

On August 6, the main body of the Tokugawa army led by Ieyasu met with the Hōjō clan's main army that was stationed at Wakamiko castle. This is where 8,000 Tokugawa soldiers fought against approximately 50,000 Hojo soldiers led by Hōjō Ujinao.{{cite book |title=East Volumes 19–20 |date=1983 |publisher=East Publications. |url=https://books.google.com/books?id=m0poGB8iQBoC |access-date=21 May 2024 |language=En}}{{cite book |author1=Okaya Shigezane |author1-link=Okaya Shigezane |title=名将言行錄 定本 · Volume 6 |date=1967 |publisher=Shin Jinbutsu Ōraisha |page=33 |url=https://books.google.com/books?id=4owfAQAAMAAJ |access-date=15 May 2024 |language=Ja}} As Ieyasu's forces lined up at Shinpu and Nomi Castle to the north and fortified their defenses, various skirmishes broke out, where the smaller Tokugawa forces managed to stall the much larger Hōjō forces.{{cite web |author1=『歴史街道』編集部 |title=真田昌幸・信尹兄弟の謀略と碓氷峠遮断 |trans-title=The conspiracy of Sanada Masayuki and Nobutada and the blockade of Usui Pass |url=https://rekishikaido.php.co.jp/detail/2871?p=1 |website=rekishikaido |publisher=PHPオンライン |access-date=12 June 2024 |pages=1–2 |language=Ja |date=2023}} In the middle of these engagements, Sakakibara Yasumasa stormed a castle belonging to the Hōjō, while Matsudaira Ietada was harassing the Hōjō food supplies.{{cite book |author1=Kōya Nakamura |title=家康傳 |date=1965 |publisher=講談社 |page=40 |url=https://books.google.com/books?id=ScEzAAAAMAAJ |access-date=22 May 2024 |language=Ja |quote=quoting Ietada Diary, Osuga Chronicles, Kanei Family Genealogy, & Sakakibara clan records}}

The Tokugawa forces then engaged in the battle of Kurokoma village against the large Hōjō army who had recently received reinforcements from the Satomi clan,{{cite book |author1=Hotta Masaatsu |title=寛政重修諸家譜: 第4輯 |trans-title=Various Kyushu clans record: Part 4 |date=1917 |publisher=榮進舍出版部 |location=Keio University |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000000869904 |access-date=17 May 2024 |language=Ja}} with 10,000 fresh soldiers led by Satomi Yoshiyori, the ruler of the Awa Province (Chiba).{{cite book |author1=Hidefumi Takei (竹井英文) |title="房相一和"と戦国期東国社会」（佐藤博信 編『中世東国の政治構造 中世東国論:上 |trans-title="'Boso Ichiwa' and the Society of the Eastern Provinces in the Warring States Period" (Hironobu Sato, ed.,) The Political Structure of the Eastern Provinces in the Middle Ages: Theory of the Eastern Provinces in the Middle Ages: Vol. 1 |date=2007 |publisher=Iwata Shoin |isbn=978-4-87294-472-3 |url=http://www.iwata-shoin.co.jp/bookdata/ISBN978-4-87294-472-3.htm |access-date=6 June 2024 |language=Ja}} To break the stalemate on the frontline, Hōjō Ujinao ordered a 10,000 troop detachment led by Hōjō Ujitada to march around the periphery of Kurokoma, intending to encircle the Tokugawa army. Ieyasu realized the Hōjō plan to encircle him, and dispatched Mizuno Katsunari and Torii Mototada to lead 2,000 soldiers to intercept them, where they managed to rout the Hōjō troops and prevent the encirclement.{{Cite book|author=長谷川正次|title=高遠藩|series=シリーズ藩物語|publisher=現代書館|date=November 2005 |isbn=4-7684-7103-X |page=50}} Katsunari along with Yasusada Miyake caused panic among the Ujinao soldiers with their assault. Hōjō Ujikatsu saw this and went to reinforce and rescue Ujitada. Katsunari and Miyake managed to repel Ujikatsu's reinforcements too. Despite quarrels with Mototada who viewed Katsunari as being reckless and not following orders, Katsunari was praised for his outstanding performance and received rewards.{{cite book |author1=kōya nakamura |title=德川家康文書の研究 – Volume 1 |trans-title=Research on Tokugawa Ieyasu Documents – Volume 1 |date=1959 |publisher=日本學術振興會發行, 丸善發賣 |page=906 |url=https://opac.yokohama-cu.ac.jp/opac/en/book/82841?target=l |access-date=20 May 2024 |language=Ja}} Due to this daring raid by Mototada and Katsunari, the Hōjō army ultimately failed to encircle to Tokugawa army. In the end, the Tokugawa clan managed to force a stalemate, as the alliance of the Hōjō and the Satomi clans which far outnumbered the Tokugawa could not dislodge them from Kurokoma.

On August 12, after a series of Tokugawa clan victories over the Hōjō clan, former Takeda clan generals including Kiso Yoshimasa, Hoshina Masanao, Yoda Nobushige, and many others, gained the confidence to openly declare their allegiance to Ieyasu.{{sfn|Hirayama|2015|pp=288–291}} Seeing the trends, Masanao's father and brother, Masatoshi and Masaaki also defected to Tokugawa.{{sfn|Hirayama|2015|pp=210–215}} In response, Ieyasu assigned his Hatamoto officer, Shibata Yasutada, to be a military inspector under Nobushige.{{Citation|author=Yamashita Masaya |title=家康の家臣団 天下を取った戦国最強軍団|series=学研M文庫|date=2011|page=162}}

At the same time, a Tokugawa army detachment from the Iga Province commanded by Hattori Hanzō invaded the Saku District, where they were aided by local Shinano samurai warriors from the Tsugane clan led by Öbi Sukemitsu. Up to this point, Ieyasu was generally still at a disadvantage in the war. In the Saku district, he only had Yoda Nobushige who was struggling by himself in guerilla warfare against the Hōjō, as the bulk of new Tokugawa supporters such as the Takekawa and Tsugane clans of Kai also suffered from a shortage of provisions while the number of anti-Hōjō forces continued to grow. In response, Yoda Nobushige took the initiative by contacting Masayuki to entice him to the Tokugawa side. By taking advantage of the Hōjō setbacks, Masayuki had placed Yazawa Tsunayori in Numata Castle and his son Sanada Nobuyuki in Iwabitsu Castle, as he started to collude with Ieyasu and Nobushige in secret.

In early September, Hattori Hanzō and Öbi Sukemitsu launched a night attack on Egusuku Castle (also known as Shishiku Castle), capturing it.{{cite book |author1=山梨県 |title=山梨県史: Chūsei IV (kōko shiryō) |date=1996 |publisher=山梨県 |page=270 |url=https://books.google.com/books?id=7Lw0AQAAIAAJ |access-date=9 June 2024 |language=Ja}}{{cite book |author1=Matsudaira Sadamasa (松平定能) |title=甲斐国志: 上, Volume 1 |date=1966 |publisher=天下堂書店 |page=706 |url=https://books.google.com/books?id=mFgfAQAAMAAJ |access-date=9 June 2024 |language=Ja}} Later, Hanzō also captured Sanogoya Castle in Izu Province under the cover of heavy rain, causing Ieyasu to elicit praise for this achievement.{{cite web |author1=コロコロさん |title=「服部半蔵正成」伊賀随一の忍者にして徳川家臣！？ |trans-title="Hattori Hanzo Masanari" Iga's greatest ninja and Tokugawa retainer!? |year=2021 |url=https://sengoku-his.com/130 |website=戦国ヒストリーのサイトロゴ |publisher=sengoku-his.com |access-date=16 July 2024 |language=Ja}} containing references from:

• Kudo Akioki, "Tokugawa Ieyasu and the Warring States Period: Ieyasu's Agent, Hattori Hanzo Masanari," 2015 (工藤章興　「〈徳川家康と戦国時代〉家康のエージェント　服部半蔵正成」　2015年)

• Yamakita Atsushi, "Illustrated Ninja," Shinkigensha, 2015 (山北篤『図解　忍者』　新紀元社　2015年)

• Kubo Fumitake, "Iga History: A Study," Iga Local History Research Association, 1986 (久保文武　『伊賀史叢考』　伊賀郷土史研究会　1986年)

• Mie Prefecture website, "Historical Information Storehouse: Hattori Hanzo and Ieyasu" (三重県HP 「歴史の情報蔵 服部半蔵と家康」)

• Shinjuku Ward website, "The Origin of the Name Hanzomon Gate - Hattori Hanzo and the Iga Police Officers" (新宿区HP 「半蔵門の名前の由来ー服部半蔵と伊賀同心ー」) In the same month, in Yamanashi Prefecture, former Takeda clan vassals led by Kōno Morimasa managed to defeat the Hōjō clan at Misaka Pass.{{efn|A mountain pass between Minamitsuru District and Misaka, Yamanashi}}{{cite book |author1=國民圖書 |title=Kansei chōshū sho kafu Vol. 4 |date=1923 |publisher=國民圖書 |location=Tokyo |page=207 |url=https://dl.ndl.go.jp/pid/1082713/1/112 |access-date=11 June 2024 |language=Ja |chapter=Kōno Morimasa|edition=Kokumin Tosho revised }}

File:Sanada Masayuki2.jpg

On October 19, Sanada Masayuki openly declared his allegiance to the Tokugawa clan by attacking Nezu Masatsuna, a lieutenant of Hōjō Ujinao, and cooperated with Yoda Nobushige to resist the Hōjō clan forces around Komoro, as Ieyasu instructed. It was believed by historians that information about Masayuki's defection had reached the Hōjō clan in early October,{{sfn|Shinichi|2005|p=34}} as there are documents and letters from Sone Masatada and Yoda Nobushige praising Sanada Masateru for his success to convince Masayuki to join the Tokugawa side. In response to Masayuki's betrayal, a commander of Hōjō forces named Fujita Ujikuni tried to capture Numata castle. However, he failed with Masayuki successfully resisting his attempt.{{sfn|Shinichi|2005|pp=35–36}}

On October 21, the Tokugawa troops in the Saku district managed to capture Mochizuki Castle. In response, the Hōjō side recalled Hōjō Tsunanari and others from Kai Province, and ordered Nyudo Urano, Lord of Ooto Castle in Agatsuma County, to immediately attack Iwabitsu Castle. Masayuki and Yoda Nobutaka then cut off communication between Komoro Castle and Tomono Castle.

Later on October 24, Ieyasu issued a Shuinjō (Red Seal Permit) to Masanao which granted him control of half of Ina district. This forced the Naito clan that had remained in Takatō Castle to switch their allegiance to the Tokugawa side. In November, Masanao attacked Minowa Castle, and caused the lord of the castle, Fujisawa Yorichika, who was on the side of Hōjō, to commit suicide. Masanao also expelled his grandson and annexed the Minowa territory. As a result, Masanao took control of the Kamiina district around Takato Castle.{{sfn|Hirayama|2015|pp=288–291}} On October 26, the Tokugawa clan managed to capture Ashida Castle, while Masayuki provided military supplies to secure the castle. Nobushige also captured Uchiyama Castle, successfully cutting off the Hōjō army's supply route. Eventually, together with Masayuki, they occupied Usui Pass, and then captured Iwamurata Castle. The battle in the Saku district was then in Tokugawa's favor, and Masayuki retreated to his main territory.

Between November 1582 to January 1583, in conjunction with the main battles at Wakamiko and Kurokoma which were still ongoing, Komai Masanao worked together with Torii Mototada and Ii Naomasa, along with Suwa Yoritada, who had joined the Tokugawa rank, to attack the Chikuma District which was controlled by Ogasawara Sadayoshi.{{sfn|Hirayama|2011 |pp=53–61}} On February 10, Sadayoshi confirmed his allegiance to them when he joined the Tokugawa side.{{sfn|Hirayama|2011 |pp=53–61}} Overall, the duration of Ieyasu's fight against the Hōjō and the Satomi clan was 80 days, and his ranks gradually swelled as more than 800 former vassals of the Takeda clan (900 according to Susumu Shimazaki) from Kōfu joined the Tokugawa clan to oppose the Hōjō.{{cite book |author1=Sakamoto Masahito |author2=hotta masaatsu |author3=Ryōshō Hayashi |title=干城錄 Volume 13 |date=1997 |publisher=人間舎 |isbn=978-4-931408-01-2 |url=https://books.google.com/books?id=74IzAQAAIAAJ |access-date=21 May 2024 |language=Ja}}

File:Bansho-in (Saku).JPG, former Takeda clan general and benefactor of Ieyasu during the Tenshō-Jingo War.{{Cite wikisource

| title = 蘆田記

| last = Kondō

| first = Heijō

| year = 1902

}} [https://ja.wikisource.org/wiki/%E8%98%86%E7%94%B0%E8%A8%98 Japan Wikisource link] taken from Japan National diet Library {{cite book |author1=Kondō Heijō |title=史籍集覧 總目解題 改定 |trans-title=Collection of historical records, 1st ed., revision |url=https://dl.ndl.go.jp/pid/1920538 |access-date=6 June 2024}}]]

The problems for the Hōjō clan increased by the day as Ieyasu established contact with daimyo lords from north-east Japan including the Satake, Yuki, and Utsunomiya clans, who threatened to invade the Hōjō from behind while the Hōjō were still engaging Ieyasu in battle. As the war turned in favor of Ieyasu, combined with the defection of Sanada Masayuki to the Tokugawa side, the Hōjō negotiated a truce with Ieyasu.{{cite book |author1=Masaru Hirayama |title=真田信之 : 父の知略に勝った決断力 |date=2016 |publisher=PHP研究所 |isbn=9784569830438 |url=https://www.book61.co.jp/book.php/N74723 |access-date=17 May 2024 |language=Ja}}

The Hōjō clan sent Hōjō Ujinobu as representative, while the Tokugawa sent Ii Naomasa as representative for the preliminary meetings.{{cite book |author1=Aida Nirō |title=日本古文書学の諸問題 |date=1976 |publisher=名著出版 |url=https://books.google.com/books?id=SrANAQAAMAAJ |access-date=15 May 2024 |language=Ja}}{{cite book |author1=千葉琢穂 |title=藤原氏族系図 6 |trans-title=Fujiwara clan genealogy 6 |date=1989 |publisher=展望社 |page=227 |url=https://www.kosho.or.jp/products/detail.php?product_id=3188838 |access-date=15 May 2024}} Representatives from the Oda clan, Oda Nobukatsu, Oda Nobutaka, and Toyotomi Hideyoshi who mediated the negotiation from October 1582, also assisted the ratification of the truce.{{harvtxt|Kazuhiro Marushima (丸島和洋)|2015|pp=33–52}} Sanada Nobutada, a younger brother of Sanada Masayuki, was given 5,000 koku of territory by Ieyasu,{{harvtxt|Shunroku Shibatsuji (柴辻俊六) 1996 |publisher=吉川弘文館 |p=72}} and Okabe Masatsuna was rewarded with a 7,600 koku domain in between Kai and Shinano provinces. In the aftermath of the war, Ieyasu once again sent Tadatsugu to subdue Suwa Yoritada at Suwa in Shinano in December, where Tadatsugu defeated Yoritada and secured his surrender to the Tokugawa clan.{{Cite book|author1=Abe Takashi|author2=Nishimura Keiko|title=戦国人名事典|trans-title=Encyclopedia of Sengoku People |edition=コンパクト|publisher=新人物往来社|date=1990|isbn=4-404-01752-9 |page=440}}

In March 1583, according to the Meishō genkō-roku record, after the destruction of the Takeda clan in the Tenmokuzan, Ieyasu organized a kishōmon (blood oath) with many samurai clans, local lords, low rank officials, ninja mercenaries, and even noble ladies that were formerly vassals of the Takeda clan in order to put them under the command of Tokugawa clan retainers.{{cite book |author1=Kokusai Bunka Shinkōkai, Center for Academic Publications Japan, Kokusai Kōryū Kikin |title=Current Contents of Academic Journals in Japan |date=1971 |publisher=Kokusai Kōryū Kikin |page=61 |url=https://books.google.com/books?id=VOYvAAAAMAAJ |access-date=9 June 2024 |language=En}} Since the ritual took place after the Tenshō-Jingo war and in the same location, this oath taking ritual was named Tenshō-Jingo kishōmon.小宮山敏和「戦国大名家臣の徳川家臣化について　戦国大名武田家家臣を事例として」『論集きんせい』26号、2004年 During the process of the oath-taking Tokugawa, Ieyasu planned to give control of most of the former Takeda samurai to Ii Naomasa to command, having consulted and reached agreement with Sakai Tadatsugu, a senior Tokugawa clan vassal. However, Ieyasu's decision garnered protest from Sakakibara Yasumasa, who went so far as to threaten Naomasa. Tadatsugu immediately defended Ieyasu's decision in response and warned Yasumasa that if he did any harm to Naomasa, Tadatsugu would personally slaughter the Sakakibara clan; Yasumasa backed down and did not protest further.{{Cite book

| author=岡谷繁実

| title=名将言行録

| publisher=岩波書店

|volume=6巻

|series =岩波文庫

|date=1944

|url=https://www.iwanami.co.jp/book/b246197.html

|isbn=9784003317365

|pages=200–291

}} As there were no more protests, Ieyasu decided to assign the new recruits to various commands, as following:{{cite book |last=丸島|first=和洋|editor1-last=柴辻|editor1-first=俊六|editor2-last=平山|editor2-first=優|editor3-last=黒田|editor3-first=基樹|editor4-last=丸島|editor4-first=和洋|page=505|chapter=土屋昌恒|date=2015|title=武田氏家臣団人名辞典|publisher=東京堂出版|isbn=9784490108606}}{{cite journal |author1=Toshikazu Komiyama |title=戦国大名家臣の徳川家臣化について |trans-title=Regarding the transformation of Sengoku daimyo vassals into Tokugawa vassals |journal=--戦国大名武田家家臣を事例として =A case study of Sengoku daimyo Takeda family vassals |date=1981 |url=https://www.meicho.co.jp/?pid=1047105 |access-date=23 May 2024 |language=Ja}}{{cite journal |author1=Toshikazu Komiyama |title=戦国大名家臣の徳川家臣化について 戦国大名武田家家臣を事例として」|trans-title=About turning Sengoku daimyo vassals into Tokugawa vassals: Using the Sengoku daimyo Takeda family vassals as an example |journal=Collection of Essays |date=2004 |volume=1 |issue=26 |url=https://ndlsearch.ndl.go.jp/books/R000000016-I2008882746 |access-date=23 May 2024 |language=Ja}}{{cite book |title=山梨県史の刊行・訂正・補足情報 |trans-title=Yamanashi Prefectural History Materials 6 Medieval Period 3 Lower Prefectural Records |url=https://www.pref.yamanashi.jp/bunka/kikaku/kenshi.html |access-date=23 May 2024 |language=Ja}}

• 70 former Takeda samurai from Tsuchiya clan, and also the clan of Ishiguro Shōgen to Ii Naomasa. (another source mentioned that total of 120 Takeda samurai warriors came under the command of Naomasa.{{harvtxt|山本博文監修|2007|p=23}})
• 11 former Takeda samurai from Komai clan led by Komai Masanao to Sakakibara Yasumasa.
• 60 former Takeda samurai of Asari clan led by Asari Masatane to Honda Tadakatsu.
• The largest number of Takeda clans vassals were under the direct control of Ieyasu himself, including clans which were led by Yoda Nobushige or Hoshina Masanao (along with the local daimyo lords from Shinano who followed Masanao).,{{Cite journal |author=Mochidzuki Hideto |title=一旗本家の目から見た近世国家 一旗本日向家の事例（二）|trans-title=The Early Modern State from the Perspective of a Hatamoto Family: The Case of the Hinata Family (2) |journal=日本福祉大学研究紀要－現代と文化 |volume= |issue=145 |publisher=日本福祉大学福祉社会開発研究所 |pages=121–141 |url=https://nfu.repo.nii.ac.jp/record/3701/files/gendai145-06mochizuki.pdf}} the Kurihara to Kurihara Nobumori,{{harvtxt|Kazuhiro Marushima (丸島和洋)|2015|p=293}} 49 samurai from the Jō clan led by father and son Jō Kageshige and Jō Masashige,{{Citation|author1=Shunroku Shibatsuji (柴辻俊六) |author2=Masaru Hirayama (平山優)|title=武田勝頼のすべて|publisher=新人物往来社|date=2007|page=229|isbn=978-4-404-03424-3}} samurai who formerly guarded the frontiers of Takeda clan led Watanabe Hitoyanosuke,{{cite book |author1=Masanori Suzuki (鈴木将典) |author2=Ryōtarō Shiba |author2-link=Ryōtarō Shiba |editor1-last=Shibatsuji |editor1-first=Shunroku |editor2-last=Hirayama |editor2-first=Masaru |editor3-last=Kuroda |editor3-first=Motoki |editor4-last=Marushima |editor4-first=Kazuhiro |title=武田氏家臣団人名辞典 |trans-title=Biographical Dictionary of Takeda Clan Vassals |date=2015 |publisher=東京堂出版 |page=718 |language=Ja |chapter=渡辺守}} and many others. Among those who were assigned as Hatamoto, or direct vassal of Ieyasu, they were allowed to retain their positions, and even increased the revenue from the domains they controlled, particularly from the new territories which the Tokugawa clan conquered. This was apparent from the Saegusa clan, where the son of the clan leader, Saegusa Masayoshi, retained his territory,{{harvtxt|Kazuhiro Marushima (丸島和洋)|2015|p=331}} while his father Saegusa Torayoshi was appointed as one of four magistrates in the Tokugawa clan.{{harvtxt|Kazuhiro Marushima (丸島和洋)|2015|pp=329–332}}

Aside from the already established workforces from the former Takeda clan, Ieyasu also established new offices such as the Hachiōji sen'nin-dōshin, which formed from a patchwork membership of nine small clans of Takeda retainers. This group continued to serve the Tokugawa clan faithfully until they were disbanded during the Meiji Restoration in 1868.{{efn|At first, their members were 250 men. Later expanded to 500 after Ieyasu transferred into the Kantō region. Later, they were appointed as guardians of Hachiōji castle, and their memberships expanded from 500 to 1,000. This is why they were called "Hachiōji sen'nin-dōshin" (Hachiōji's 1,000 officers.{{Cite journal|author=高橋磌一|date=July 1936 |title=八王子千人同心について|url=https://koara.lib.keio.ac.jp/xoonips/modules/xoonips/detail.php?koara_id=AN00100104-19360700-0129|journal=史学|volume=15|issue=2|pages=129–161|publisher=三田史学会}}}}

In 1583, Ieyasu had a detachment of Ii Naomasa's troops conquer the Takatō area of Shinano, which had still not submitted to the Tokugawa clan.{{cite web |author1=hiroyuki kikuchi (菊地浩之) |title=｢井伊の赤鬼｣と恐れられた直政は実は名将ではなかった…関ヶ原の合戦後42歳で死んだ徳川四天王最年少の生涯 |url=https://president.jp/articles/-/75500?page=2 |website=President Online（プレジデントオンライン） |access-date=4 June 2024 |pages=1–5 |language=Ja |date=2023|quote=Hiroko Noda; Ii Naomasa; Hikone castle Museum}} Meanwhile, Nobushige led the attack against the Tomono clan, and defeated them.{{cite book |author1=Nagano Prefecture |title=長野県史 通史編 第3巻 中世 |trans-title=Nagano Prefecture History General History Volume 3 Middle Ages |date=1987 |publisher=Nagano Prefecture History Publishing Association |location=Nagano (city) |page=371 |url=https://ndlsearch.ndl.go.jp/books/R100000001-I19111009950844410 |access-date=6 June 2024 |language=Ja}}

In the middle of operation, Yoda Nobushige was killed in action. Yoda Yasukuni, who succeeded him as head of the Yoda clan, was given the surname Matsudaira and Komoro Castle. The territory he was allowed to inherit was 60,000 koku, one of the largest for any of Ieyasu's vassals at the time.{{cite web |title=依田（芦田）信蕃（のぶしげ） |trans-title=Yoda Nobushige (Ashida) |url=https://www.komoro-tour.jp/spot/castle/history/person03/ |website=こもろ観光局Komoro Tourism Bureau |publisher=Komoro Tourism Bureau |access-date=6 June 2024 |language=Ja}} Yashiro Hidemasa, who surrendered to Ogasawara Sadayoshi, also joined the Tokugawa clan later on April 1, 1584, together with his younger brother Ogasawara Mitsutoshi.{{sfn|Hirayama|2011|p=128}}{{harvtxt|Kazuhiro Marushima (丸島和洋) |Shunroku Shibatsuji (柴辻俊六) |Masaru Hirayama (平山優) |Motoki Kuroda (黒田基樹) |2015|p=677}}

Ieyasu did not take a side during the Toyotomi Hideyoshi and Shibata Katsuie conflict, where Hideyoshi defeated Katsuie at the Battle of Shizugatake.{{rp|314}}

{{see also|Battle of Komaki and Nagakute}}

File:Nagakute Historic Battlefield.jpg ]]

As the Tokugawa clan's territory expanded, many of their regions were hit by earthquakes and heavy rains from 1583 to 1584. In particular, from May to July, heavy rains fell constantly from the Kantō region to the Tōkai region, in what was dubbed the "heaviest flood in 50 years" in the historical record of Ietada-nikki.{{cite book |title=家忠日記 / Ietada nikki |date=1968 |publisher=Rinsen Shoten |location=Kyōto |url=https://search.worldcat.org/title/ietada-nikki/oclc/20953775 |access-date=3 June 2024 |language=Ja |author=Matsudaira Ietada (Fukōzu)}} It was under these circumstances that the Tokugawa clan was forced to fight against the Hōjō clan and the Toyotomi government, because in 1584 Ieyasu had decided to support Oda Nobukatsu, the eldest surviving son and heir of Oda Nobunaga, against Toyotomi Hideyoshi. The Ryumonji Kojiki, written by successive chief priests at Ryumonji Temple in Tahara, Mikawa Province, records that in 1582 many people were mobilized in the Battle of Komaki and Nagakute, which led to the devastation of farmland and famine.

The devastation of the Tokugawa clan's territory made it difficult to continue fighting against the Toyotomi government and they were forced to rebuild their country.{{Citation|author=Shiba Ryutaro |chapter=戦国大名徳川氏の徳政令|editor=Masaki Kubota |title=松平家忠日記と戦国社会|publisher=Iwata Shoin |date=2011}}/Retitled:{{Citation|author=Shiba Ryutaro |chapter=徳川氏の領国支配と徳政令|title=戦国・織豊期大名徳川氏の領国支配|publisher=Iwata Shoin |date=2014}} This was a dangerous situation for the Tokugawa clan which could have resulted in their annihilation due to the Oda clan collapsing after Nobunaga's death.{{cite book |author1=Arthur Lindsay Sadler |author1-link=Arthur Lindsay Sadler |title=The Maker of Modern Japan The Life of Tokugawa Ieyasu |date=2014 |publisher=Taylor & Francis |isbn=9781136924705 |pages=123–124 |url=https://books.google.com/books?id=oftisLbVFwgC |access-date=9 May 2024 |language=En}}

Tokugawa troops took the traditional Oda stronghold of Owari. Hideyoshi responded by sending an army into Owari. Ieyasu decided to confront Hideyoshi's forces in Komaki because his general, Sakakibara Yasumasa, suggested the area was favorable for the Tokugawa force to fight incoming enemies from the west.{{harvtxt|Stephen Turnbull |2013 |pp=162–163}} Additionally, Ieyasu and Nobukatsu formed an anti-Hideyoshi alliance with Chōsokabe Motochika, through contact with Kōsokabe Chikayasu.{{Cite book|author = Dai Yamamoto|year = 1988 |title = 長宗我部元親 |edition = 新装版 |publisher = 吉川弘文館 |isbn = 4642051031 |trans-title=Chosokabe Motochika |page=103}}

File:Hoshizaki Castle 001.JPG

At first, Ieyasu ordered his generals Mizuno Tadashige and Mizuno Katsunari to capture Hoshizaki Castle.{{cite book |author1=Funahashi Takeshi | author2=Nagakute Katsunari |title=見た聞いた考えた豊臣秀吉大研究 地元にいるから秀吉が見えてきた! |date=1983 |publisher=ブックショップマイタウン |page=191 |url=https://ndlsearch.ndl.go.jp/books/R100000001-I23211009210126478 |access-date=20 May 2024 |language=Ja}} Then, as the Toyotomi army vanguard under the command of Toyotomi Hidetsugu started entering the area of Komaki, Ieyasu sent Yasumasa and Osuga Yasutaka in for a surprise attack and inflicted heavy losses on the Hidetsugu army before they were stopped by Hori Hidemasa. Hidemasa decided to retreat when Ieyasu brought his main forces forward.{{cite book |author1=Tetsuo Owada |author1-link=Tetsuo Owada |script-title=ja:豊臣秀次: 「殺生関白」の悲劇 |date=2002 |publisher=PHP 硏究所 |isbn=9784569621043 |url=https://books.google.com/books?id=Fn1xBAAAQBAJ |access-date=11 May 2024 |language=Ja}}

Later, as another Toyotomi vanguard led by Mori Nagayoshi entered the area, Ieyasu had his senior generals, Sakai Tadatsugu, Okudaira Nobumasa, and Matsudaira Ietada, beat Nagayoshi's troops, forcing him to retreat.{{cite book |author1=Stephen Turnbull |author1-link=Stephen Turnbull (historian) |title=Toyotomi Hideyoshi |date=2011 |publisher=Bloomsbury Publishing |isbn=9781846039614 |page=39 |url=https://books.google.com/books?id=HC61CwAAQBAJ |access-date=6 May 2024 |language=En}} In the last phase of this series of engagements, Nagayoshi returned with another Toyotomi general Ikeda Tsuneoki. However, both of them were repeatedly beaten on the field at Nagakute by Mizuno Katsunari,{{harvtxt|Kusudo Yoshiaki |2009 |p=14}} and later, Ii Naomasa, caused the Toyotomi forces to suffer heavy losses with both Tsuneoki and Nagayoshi killed in action.{{Cite journal|author=花見朔已|date=1942|title=小牧・長久手の役|journal=大日本戦史|publisher=三教書院|page=44}}{{harvtxt|参謀本部 編 |1978|pp=35–39|}}

Furious with the decimation of Nagayoshi's and Tsuneoki's forces, Hideyoshi mobilized his main army to crush Ieyasu's army in Nagakute. However, Ieyasu had already retreated before Hideyoshi's main forces arrived.{{sfn|Stephen Turnbull|2012|p=27}}{{cite book |title=Mikawa Go Fudoki Seisetsu Daizen Volume 42 & 43 |date=1853 |publisher=Aichi Prefectural Library |url=https://websv.aichi-pref-library.jp/wahon/detail/174.html |access-date=4 May 2024 |language=ja}}

After the Battle of Komaki and Nagakute in April, the front line in northern Owari reached a stalemate. At this time, Kanie Castle was located about three miles between Ieyasu's Kiyosu Castle and Nobuo's Nagashima Castle, and was connected to the Mie moat and three castles: Ono Castle, Shimojima Castle, and Maeda Castle. At that time, Kanie Castle was facing the sea and was one of the leading ports in Owari, along with Atsuta and Tsushima. Then on June 18, Ieyasu and Nobuo led 20,000 soldiers and besieged three castles: Kanie Castle, Maeda Castle, and Shimojima Castle.{{cite book |author1=Fujita Tatsuo |title=小牧・長久手の戦いの構造 |trans-title=Structure of the Battle of Komaki and Nagakute |date=2006 |publisher=岩田書院 |isbn=4-87294-422-4 |page=107 |url=http://www.iwata-shoin.co.jp/bookdata/ISBN4-87294-422-4.htm |access-date=14 May 2024 |language=Ja}} Kanie Castle was defended by Maeda Nagatane and Takigawa Kazumasu. Tadatsugu, Okanabe Mori, and Yamaguchi Shigemasa spearheaded the attack towards Shimojima castle, while Sakakibara Yasumasa, Osuga Yasutaka were deployed to capture any fleeing defenders.{{cite book |author1=神谷存心 |title=小牧陣始末記(日本戦史材料; 第1巻) |trans-title=The story of the end of the Komaki camp (Japanese military history materials; Volume 1) |date=1889 |publisher=武蔵吉彰 |location=Tokyo |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000000431253 |access-date=14 May 2024 |language=Ja}}{{cite book |author1=Kimura Takaatsu |editor1-last=Naotoki |editor1-first=Tamaru |title=武徳編年集成 |publisher=拙修斎 |url=https://www.digital.archives.go.jp/file/1217291.html |access-date=14 May 2024 |language=Ja}}

During this siege, Ieyasu's hatamoto retainers, including Mizuno Katsunari, blockaded the port of the castle and hijacked two ships belonging to Kuki Yoshitaka to prevent any outside help for Kanie Castle.{{sfn|Hirai|1992|p=52}} After the fall of Shimojima castle on June 22, Oda Nobuo and Tokugawa Ieyasu launched an all-out attack on Kanie Castle. The soldiers led by Tadatsugu, who had been deployed at the main gate, were exhausted after days of fierce fighting, and in the evening, the soldiers of Yasumasa Sakakibara and Ietada Matsudaira entered Kaimonjiguchi in their place.{{cite book |author1=Narushima shichoku |author2=Udagawa Takehisa |author3=kuwata tadachika |title=改正三河後風土記 Volume 1 |trans-title=Revised Mikawa Go Fudoki Volume 1 |date=1976 |publisher=秋田書店 |page=197 |url=https://books.google.com/books?id=-IEzAQAAIAAJ |access-date=14 May 2024 |language=Ja}} On June 23, Ieyasu entered the castle with Sakakibara Yasumasa, subduing the castle.

The conflict with Hideyoshi was long, and lasted until Nobukatsu decided to surrender to Hideyoshi. With this, Ieyasu lost his motivation to further oppose Hideyoshi and decided to also submit.{{sfn|Turnbull|1998|p=235}} After peace negotiations between Tokugawa Ieyasu and Toyotomi Hideyoshi in the aftermath of the Battle of Komaki and Nagakute, Naomasa, Tadakatsu, and Yasumasa gained fame in Kyoto. The following month, the three of them were joined by Tadatsugu Sakai while accompanying Ieyasu on a trip to Kyoto, where the four of them became famous.{{cite book |author1=Tetsuo Nakamura |author2=Kazuo Murayama |title=徳川四天王: 精強家康軍団奮闘譜 歴史群像シリーズ22号 |date=1991 |publisher=学研プラス |isbn=4051053679 |pages=111, 125 }}

However, on November 13, 1585, Ishikawa Kazumasa defected from Ieyasu to Hideyoshi.{{sfn|Tanaka|2007|p=14}} Ogasawara Sadayoshi, who also defected and followed Kazumasa, led over 3,000 troops to attack Takato. In Takato Castle there were only 40 cavalrymen and 360 soldiers other than the elderly Hoshina Masatoshi, but Masatoshi himself took command and defeated the Ogasawara forces in open battle. This prevented the collapse of Tokugawa rule in Shinano and Ieyasu awarded Masanao with the sword of Tsunehisa on December 24 in recognition of his military achievements.{{sfn|Hirayama|2011|p=179-182}}

These incidents caused Ieyasu to undertake massive reforms of the Tokugawa clan governmental structure by incorporating more Takeda clan vassals into his administrations, both civil and military. At first, Ieyasu ordered Torii Mototada, who served as the county magistrate of Kai, to collect military laws, weapons, and military equipment from the time of Takeda Shingen and bring them to Hamamatsu Castle in Hamamatsu City, Shizuoka Prefecture. Later, he appointed two former Takeda vassals, Naruse Masakazu and Okabe Masatsuna, as magistrates under authority of Ii Naomasa and Honda Tadakatsu. He ordered all former Takeda vassals who served him to impart any military doctrines and structures they knew from their service to the Takeda clan.,{{cite book |author1=Okanoya Shigezane |translator=Andrew and Yoshiko Dykstra |title=Shogun and Samurai Tales of Nobunaga, Hideyoshi, and Ieyasu |date=2007 |publisher=University of Hawaiʻi; Japanese Literature Translations by Yoshiko K. Dykstra |location=Mānoa |page=147 |url=https://scholarspace.manoa.hawaii.edu/server/api/core/bitstreams/0d434090-1065-4bc9-ab1f-31611d094ba2/content |access-date=2 June 2024 |language=En}} He ordered three of his prime generals, Ii Naomasa, Honda Tadakatsu, and Sakakibara Yasumasa, to serve as the supreme commanders of these new military regiments.{{cite web |author1=Watanabe Daimon |title=家臣が出奔するというピンチをチャンスに変えた、徳川家康の先見性とは |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |website=yahoo.co.jp/expert/articles/ |url=https://news.yahoo.co.jp/expert/articles/a826d1080466b78200a81bb25683c64862298924 |access-date=2 June 2024 |language=Ja}} The same year, Hideyoshi forced his younger sister Asahi no kata to divorce her husband, who then committed suicide, and sent her to Ieyasu with the offer of marrying her.{{Sfn|Fujino |1990|p=59}}

In 1586, in response to Ishikawa Kazumasa's defection from the Tokugawa clan, former Takeda clan vassals from Kai and Shinano province, including Yonekura Tadatsugu, sought to reaffirm their loyalty to Ieyasu by presenting their family members as hostages.{{harvtxt|Kazuhiro Marushima (丸島和洋)|2015|p=706}}

Later the same year, Hideyoshi sent his own mother as a hostage to Ieyasu. If Ieyasu continued to refuse to go to Kyoto after such a gesture, it would give Hideyoshi a just cause for war. Ieyasu finally decided to become Hideyoshi's vassal.{{cite web|url=https://hamamatsu-daisuki.net/ieyasu/person/relation/|title=1586年に秀吉の母・大政所を人質として岡崎に迎えた後に上洛。大坂城で秀吉に臣下の礼をとり、秀吉の家来となりました。|publisher=Hamamatsu & Lake Hamana Tourism Bureau|access-date=June 7, 2024}}

{{see also|Siege of Odawara (1590)|Edo}}

File:Odawara-jo.jpg

In 1590 May, Ieyasu participated in the campaign against the Hōjō clan. Odawara, which was the last Hōjō clan stronghold, saw almost no significant military action, with the exception of Ii Naomasa's night raid attack. This happened after a group of miners from Kai Province dug under the castle walls, allowing troops under Naomasa to enter and engage the enemy.{{sfn|Turnbull|1998|p=241}} After the surrender of the Hōjō clan, Ieyasu sent Naomasa and Sakakibara Yasumasa with 1,500 soldiers to witness the seppuku of the defeated enemy generals, Hōjō Ujimasa and Hōjō Ujiteru.{{cite book |author1=kuwata tadachika |author2=yamaoka sōhachi |author3=Army. General Staff Headquarters |title=日本の戦史 Volume 4 |date=1965 |publisher=德間書店, 昭和 40–41 [1965–66] |location=Japan |page=263 |url=https://books.google.com/books?id=yAkmAAAAMAAJ |access-date=16 May 2024 |language=Ja}} As result of his distinguished service during the campaign, Naomasa was awarded with an increase in his domain to 120,000 koku.{{cite book |author1=高崎市史編さん委員会 |title=高崎市史 Volume 1 |date=1968 |publisher=高崎市 |page=151 |url=https://books.google.com/books?id=hdwNAAAAMAAJ |access-date=9 May 2024 |language=Ja}} Daidōji Masashige, a senior Hōjō clan retainer, was also forced to commit seppuku by Hideyoshi, however, his children were spared from execution at the behest of Ieyasu. The eldest son, Daidōji Naoshige, became Ieyasu's vassal after the death of Ujinao.{{cite web |author1=とーじん さん |title=「大道寺政繁」北条氏の重臣として内政・軍事両面で活躍も、最期は処刑された悲運の将 |trans-title="Daidouji Masashige" was a senior retainer of the Hōjō clan, and played an active role in both domestic and military affairs, but was executed in the end |url=https://sengoku-his.com/352 |website=戦国ヒストリー |publisher=sengoku-his.com |access-date=11 June 2024 |language=Ja |date=2019 |quote=Haruhisa Shimoyama, (後北条氏家臣団人名事典 / Biographical Dictionary of the Later Hojo Clan's Vassals) Tokyodo Publishing, 2006; Kuroda Motoki, (北条氏康の家臣団：戦国「関東王国」 / Hojo Ujiyasu's Vassals: The Family and Elders Who Supported the Kanto Kingdom in the Warring States Period) Yosensha, 2018; Kuroda Motoki, (戦国北条家一族事典 / Encyclopedia of the Hojo Clan in the Warring States Period), Ebisu Kosho Publishing, 2018.}}

On October 28 of the same year, a {{Ill|Waga-Hienuki Rebellion|lt=massive revolt|jp|和賀・稗貫一揆}} against the Toyotomi government in Mutsu Province was incited by Hienuki Hirotada and Waga Yoshitada. In response, Hideyoshi sent a punitive expedition with an army 30,000 strong led by Ieyasu Tokugawa, Toyotomi Hidetsugu, Date Masamune, Ishida Mitsunari, Ōtani Yoshitsugu, Gamō Ujisato, Uesugi Kagekatsu, Satake Yoshishige, and Maeda Toshiie in order to pacify the rebellion.{{cite book |author1=青森県 |title=青森県史: 資料編. 中世, Volume 1 |trans-title=Aomori Prefectural History: Documents. Middle Ages, Volume 1 |date=2004 |publisher=Aomori Prefecture History Editor Medieval Section|pages=274, 702 |url=https://www2.i-repository.net/contents/kenshi-front/ |access-date=19 May 2024 |language=Ja}}

In 1591, Ieyasu gave up control of his five provinces (Mikawa, Tōtōmi, Suruga, Shinano, and Kai) and moved all his soldiers and vassals to his eight new provinces in the Kantō region. The proclamation of this decision happened on the same day as Hideyoshi entered Odawara castle after the Hōjō clan formally surrendered. The moment Ieyasu was appointed to rule Kantō, he immediately assigned his premier vassals, including Ii Naomasa, Honda Tadakatsu, Sakakibara Yasumasa, and Sakai Ietsugu, the son of Sakai Tadatsugu, to each control a large area of the former Hōjō clan territories in Kantō. Historians saw this step as aimed at bringing order to the newly subdued population of the area, while also guarding the eastern domains from any influence or threat from the Satomi clan, which had not yet submitted to Toyotomi rule at that time.{{cite journal |author1=Yuu Kawamura |title=徳川家康の新領国に対する家臣団配置―小田原落城直後の上総の一動向― |journal=『歴史手帳』6巻2号）(History Notebook, Vol. 6, No. 2)|trans-title=Deployment of Tokugawa Ieyasu's vassals in his new territory: Movements in Kazusa immediately after the fall of Odawara Castle |language=Ja}}{{cite book |author1=Otaki Town History Editorial Committee |title=大多喜町史 |trans-title=Otaki Town History |date=1991 |location=Otaki, Chiba Prefecture |pages=310–311 |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000002127280 |access-date=22 May 2024}} Meanwhile, Ieyasu himself established his personal seat of power in Edo town, which at that time was an underdeveloped town in Kantō.{{sfn|Nakamura|2010|p=210}}

File:Kanto Region in Japan.svg

Historian Adam Sadler saw this step as the riskiest Ieyasu ever made—to leave his home province and rely on the uncertain loyalty of the former Hōjō clan samurai in Kantō. In the end, it worked out brilliantly for Ieyasu. He reformed the Kantō region, controlled and pacified the Hōjō samurai, and improved the underlying economic infrastructure. Also, because Kantō was somewhat isolated from the rest of Japan, Ieyasu was able to ally with daimyo of north-eastern Japan including Date Masamune, Mogami Yoshiaki, Satake Yoshishige and Nanbu Nobunao; he was also able to maintain a unique level of autonomy from Toyotomi Hideyoshi's rule. Within a few years, Ieyasu had become the second most powerful daimyo in Japan. An anecdotal proverb says, "Ieyasu won the Empire by retreating."Sadler, p. 164.

Modern Japanese historians reject that this was a deliberate move by Ieyasu since it was an order from Hideyoshi. Nevertheless, Watanabe Daimon stated that, while the general opinion was that Ieyasu was reluctant about his transfer to Kantō, this perception was unfounded. Instead, Daimon suspected that Ieyasu actually responded to this transfer positively as he saw potential in making undeveloped Edo into his seat of power.{{cite web |title=徳川家康は泣く泣く江戸に行ったのではなく、実は前向きだった |url=https://news.yahoo.co.jp/expert/articles/af0ad7e21140c617714675385d17bea40f7b2f45 |website=yahoo.co.jp/expert |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=2 June 2024 |author=Watanabe Daimon|language=Ja |date=2023}}{{efn|Historian Andō Yūichirō added, the true intention of Hideyoshi in transferring Ieyasu to Kantō was to weaken the power of the Tokugawa clan by moving them from their ancestral land in Mikawa, as he expected the former Hōjō vassals in Kantō would rebel against Ieyasu. However, Kahara Toshi stated recent academic consensus is that this step by Hideyoshi would better viewed as a sign of his trust in Ieyasu's capability to rebuild the post-war Kantō.{{cite web |author1=Kahara Toshi |title=｢家康へのいやがらせ｣ではなかった…最新研究でわかった｢秀吉が家康を関東に追いやった本当の理由｣ |trans-title=It wasn't "harassment for Ieyasu"...Recent research reveals "the real reason Hideyoshi drove Ieyasu to Kanto |url=https://president.jp/articles/-/74422?page=1 |website=President Online |access-date=4 June 2024 |pages=1–4 |language=Ja |date=2022}}}}

Similarly, Andō Yūichirō viewed this transfer as an advantage for the Tokugawa regime in the long run, as this move was not only doubled the territory that he controlled, but it further added numerous new vassals in Kantō to the already impressive political and military power of the Tokugawa regime, which had already absorbed the armies of the Imagawa and Takeda clans before. Yūichirō added that aside from the samurai from Imagawa, Takeda, and Hōjō, the Mikawa samurai clans who were traditional followers of the Tokugawa clan also lost their sense of independence after being transferred into a new unfamiliar territory, which increased their sense of dependence on Ieyasu, in effect further minimizing the possibility of them going renegade and betraying Ieyasu, as Ishikawa Kazumasa had done several years earlier.{{cite web |author1=Andō yūichirō |title=だから織田と豊臣はあっさり潰れた…徳川家康が｢戦国最後の天下人｣になれた本当の理由 |trans-title=The reason why Oda and Toyotomi were easily defeated... Tokugawa Ieyasu was the "last of the Sengoku period." |url=https://president.jp/articles/-/64535?page=1 |website=President Online |access-date=4 June 2024 |pages=1–4 |language=Ja |date=2022}}

After the Waga-Hienuki rebellion, the Kunohe rebellion led by Kunohe Masazane broke out on March 13, 1591. This caused the punitive expedition army to split their forces as Ieyasu, Naomasa, Ujisato, and some commanders changed their focus to suppress Masazane's rebellion first.{{harvtxt|Seiji Kobayashi |1994 |p=189}}{{cite book |author1=Iwate Prefectural Educational Research Institute |title=岩手県史 |trans-title=Iwate Prefecture History |date=1966 |publisher=杜陵印刷 |page=105 |url=https://ndlsearch.ndl.go.jp/en/books/R100000002-I000001190277 |access-date=15 May 2024 |language=Ja}} Ieyasu, who at that time was also busy suppressing rebellions with his main commanders, including Sakakibara Yasumasa, Ii Naomasa, and Honda Tadakatsu, arrived at Iwatesawa, Tamazukuri district, Mutsu (modern day Iwadeyama, Miyagi Prefecture) on August 18, where he camped until October and led the troops.{{cite book |author1=所沢市史編さん委員会 |title=所沢市史, Volume 10 |date=1979 |publisher=所沢市 |page=466 |url=https://books.google.com/books?id=3gE0AQAAIAAJ |access-date=30 May 2024 |language=Ja}}

During the operation against the Kunohe clan rebels, Naomasa Ii became the vanguard with Nanbu Nobunao. As they advanced towards Kunohe castle, they faced a small force of Kunohe rebels which they easily defeated. Naomasa suggested to besiege the castle until they surrendered, which was met with agreement.{{cite book |author1=Ishidoriya Town History Compilation Committee |title=石鳥谷町史 上-下卷 [1-2] · Volume 1 |date=1979 |publisher=石鳥谷町 |page=299 |url=https://books.google.com/books?id=dBs5AAAAMAAJ |access-date=15 May 2024}}

On 4 September, the rebels executed the prisoners inside the castle and incited mass suicide after setting fire to the castle. The castle burned for three days and nights killing all within.{{cite book|last=Turnbull|first=Stephen|title=Hatamoto: Samurai Horse and Foot Guards 1540-1724|year=2010|publisher=Osprey|language=English|isbn=9781846034787}} The rebellions were suppressed by June 20, with Waga Yoshitada being slain in battle,{{cite book |author1=中央公論新社(編) |title=歴史と人物 Volume 11 |trans-title=History and People volume 11 Interesting People Japanese History Ancient and Medieval Edition |date=2020 |publisher=中央公論新社(編) |isbn=9784128001453 |page=104 |url=https://books.rakuten.co.jp/rb/17253284/ |access-date=19 May 2024 |language=Ja}} while Hienuki Hirotada was sentenced to "Kaieki law" which stated that his and his clan's status and rights as samurai were stripped.{{Cite book|author=Hosoi Kei |title=南部と奥州道中 |trans-title=Nanbu and Oshu Road |url=https://www.yoshikawa-k.co.jp/book/b33887.htm|publisher=Yoshikawa Kobunkan|date=2002|page=104 |isbn=4642062068}}

As the operation ended, Ieyasu returned to Edo on October 29 and began managing his new territory in the Kantō region. Ieyasu managed to establish his home base in Kantō, and built sustainable economic infrastructure in the region.{{sfn|Nishimoto|2010|p=141}} Ieyasu also employed Gotō Shōzaburō, head of the gold mining and metal industries of the Sengoku period, to mint gold coins and establish a bank-like institution for the Tokugawa clan's government.{{cite web |author1=Takayuki Emiya (江宮隆之) |author2=Rekishijin Editorial Department |title=徳川幕府の日本銀行・金座の当主であった造幣ブレーン「後藤庄三郎」とは？ |trans-title=Who was Goto Shozaburo, the minting brain behind the Tokugawa Shogunate's Bank of Japan and Gold Mint? |url=https://www.rekishijin.com/28213 |website=Rekishijin |publisher=ABC ARC, inc. |access-date=24 June 2024 |language=Ja |date=2023 |quote=From "The Truth About Tokugawa Ieyasu" in the February 2023 issue of Rekishijin article}}

In 1592, Toyotomi Hideyoshi invaded Korea as a prelude to his plan to attack China. The Tokugawa clan samurai didn't take part in this campaign, as Hideyoshi had ordered the eastern provinces' daimyo including Ieyasu, Uesugi Kagekatsu, and Date Masamune to maintain logistical support for the war effort in Nagoya Castle.{{efn|Historian Kōichirō Hamada examined the historical records regarding the Korean invasion where Ieyasu expressed his eagerness to participate in this campaign. However, Hideyoshi organized to prioritize the daimyo lords from western provinces as vanguard which divided into 9 divisions, as he saw their positions were closer to Korea. Hamada stated by the fact that Korean invasion were dragged for years, there is good possibility that Ieyasu and other eastern province daimyo lords would be sent to Korea if Hideyoshi lived longer and the Korean campaign continues.{{cite web |author1=Kōichirō Hamada (田 航一郎) |title=暴走する秀吉を誰も止められなかった…名だたる武将が出兵する中､なぜ家康は朝鮮出兵を回避できたのか |url=https://president.jp/articles/-/74100?page=1 |website=president.jp |access-date=4 June 2024 |pages=1–4 |language=Ja |date=2023}}}}

In 1593, Toyotomi Hideyoshi fathered a son and heir, Toyotomi Hideyori. Later, though still in early 1593, Ieyasu himself was summoned to Hideyoshi's court in Nagoya (in Kyushu, not the similarly spelled city in Owari Province) as a military advisor and was given command of troops meant as reserves for the Korean campaign. Ieyasu stayed in Nagoya intermittedly for the next five years.{{cite book |url=https://books.google.com/books?id=0syC6L77dpAC&pg=PA353 |title=A History of Japan, 1334–1615 |first= Sir George Bailey |last=Sansom |publisher= Stanford University Press |year= 1961 |isbn= 0-8047-0525-9 |page=353}}

In July 1595, the "Toyotomi Hidetsugu Incident" occurred. In response to this major incident shaking the Toyotomi government, Hideyoshi ordered various daimyo to come to Kyoto in an attempt to calm the situation. Ieyasu also came to Kyoto on Hideyoshi's orders. From this point on, Ieyasu spent longer and longer periods in Fushimi Castle than in his underdeveloped residence, Edo Castle. Due to this chain of events, Ieyasu's position in the Toyotomi government had risen, but by being at the center of the government, Ieyasu was able to learn directly about the central government's political system.{{Cite book |author=Tetsuo Owada |trans-title=Tokugawa Ieyasu, the Great Leader of Sunpu |author-link=Tetsuo Owada |year= 2007 |title= 駿府の大御所 徳川家康 |publisher= 静岡新聞社 |series= 静新新書}}

{{Main|Council of Five Elders}}

[[File:Joint letter of Five Elders (of Toyotomi).jpg|300px|thumb|The signatures of the Five Elders. From the top left, Uesugi Kagekatsu and Mori Terumoto, from the bottom left, Ukita Hideie, Maeda Toshiie, and Tokugawa Ieyasu. The bottom row is upside down.

]]

In 1598, with his health clearly failing, Hideyoshi called a meeting that would determine the Council of Five Elders, who would be responsible for ruling on behalf of his son after his death. The five that were chosen as tairō (regents) for Hideyori were Maeda Toshiie, Mōri Terumoto, Ukita Hideie, Uesugi Kagekatsu, and Ieyasu, who was the most powerful of the five. This change in the pre-Sekigahara power structure became pivotal as Ieyasu turned his attention towards Kansai; at the same time, other ambitious (albeit ultimately unrealized) plans, such as the Tokugawa initiative establishing official relations with New Spain (modern-day Mexico), continued to unfold and advance.Nutall, Zelia. (1906). The Earliest Historical Relations Between Mexico and Japan, p. 2[https://www.nytimes.com/1930/11/03/archives/japan-to-decorate-kind-alfonso-today-emperors-brother-nears-madrid.html "Japan to Decorate King Alfonso Today; Emperor's Brother Nears Madrid With Collar of the Chrysanthemum for Spanish King"]. The New York Times, November 3, 1930, p. 6.

Toyotomi Hideyoshi, after three more months of deteriorating health, died on September 18, 1598. He was nominally succeeded by his young son Hideyori but as he was just five years old, the real power was in the hands of the regents.{{citation needed|date=May 2024}} There were several incidents involving Ieyasu after the death of Hideyoshi:

• The government of Japan under Toyotomi's rule had an incident when seven military generals (Fukushima Masanori, Katō Kiyomasa, Ikeda Terumasa, Hosokawa Tadaoki, Asano Yoshinaga, Katō Yoshiaki, and Kuroda Nagamasa) came into conflict with Ishida Mitsunari. It was said that the reason for this was that they were dissastisfied with Mitsunari because he wrote poor assessments and underreported their achievements during the Imjin War against Korea and the Chinese empire. At first, these generals gathered at Kiyomasa's mansion in Osaka Castle, and from there they marched to Mitsunari's mansion. However, Mitsunari learned of this through a report from a servant of Toyotomi Hideyori named Jiemon Kuwajima and he fled to Satake Yoshinobu's mansion together with Shima Sakon and others to hide.{{Cite journal |author =Mizuno Goki |title = 前田利家の死と石田三成襲撃事件 |trans-title=Death of Toshiie Maeda and attack on Mitsunari Ishida |date = 2013 |journal = 政治経済史学 |issue = 557号 |pages = 1–27 |url=https://cir.nii.ac.jp/crid/1520290885037880832 |language=Ja}} When the seven generals found that Mitsunari was not in the mansion, they searched the mansions of various feudal lords in Osaka Castle, and Katō's army approached the Satake residence. Mitsunari and his party then escaped from the Satake residence and barricaded themselves at Fushimi Castle.{{Cite journal |author = Kasaya Kazuhiko|title = 豊臣七将の石田三成襲撃事件―歴史認識形成のメカニズムとその陥穽― |trans-title=Seven Toyotomi Generals' Attack on Ishida Mitsunari – Mechanism of formation of historical perception and its downfall |date = 2000 |journal = 日本研究 |issue = 22集 |language=Ja}}

The next day, the seven generals surrounded Fushimi Castle with their soldiers as they knew Mitsunari was hiding there. Ieyasu, who was in charge of political affairs in Fushimi Castle at that moment, attempted to arbitrate the situation. The seven generals requested Ieyasu hand over Mitsunari, which Ieyasu refused. Ieyasu then negotiated a promise to let Mitsunari retire and to review the assessment of the Battle of Ulsan Castle in Korea. Ieyasu had his second son, Yūki Hideyasu, escort Mitsunari to Sawayama Castle.{{Cite journal |author = Kasaya Kazuhiko |title = 徳川家康の人情と決断―三成"隠匿"の顚末とその意義― |trans-title=Tokugawa Ieyasu's humanity and decisions – The story of Mitsunari's "concealment" and its significance |date = 2000 |journal = 大日光 |issue = 70号 }}{{efn|historian Watanabe Daimon stated from the primary and secondary sources text about the accident this was more of legal conflict between those generals with Mitsunari, rather than conspiracy to murder him. The role of Ieyasu here was not to physically protect Mitsunari from any physical harm from them, but to mediate the complaints of those generals.{{cite web |title=七将に襲撃された石田三成が徳川家康に助けを求めたというのは誤りだった |url=https://news.yahoo.co.jp/expert/articles/b9b580be2b347ecaf183e72ab6eb4039a09af98d |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=2 June 2024 |language=Ja}}}}{{efn|Historians viewed this incident were not just simply personal problems between those seven generals against Mitsunari, as it was viewed as an extension of the political rivalries between the Tokugawa faction and the anti-Tokugawa faction which was led by Mitsunari. Following this incident, those military figures on bad terms with Mitsunari would support Ieyasu later during the conflict of Sekigahara between the Eastern army led by Tokugawa Ieyasu and the Western army led by Ishida Mitsunari.{{Cite book|author=Mizuno Goki|chapter=石田三成襲撃事件の真相とは|trans-title=What is the truth behind the Ishida Mitsunari attack?|editor1=Watanabe Daimon |title=戦国史の俗説を覆す|publisher=柏書房|date=2016|language=Ja}} Muramatsu Shunkichi, writer of "The Surprising Colors and Desires of the Heroes of Japanese History and violent womens”, gave his assessment that the reason of Mitsunari failure in his war against Ieyasu was due to his unpopularity among the major political figures of that time.{{cite book |title=歴代文化皇國史大觀 |trans-title=Overview of history of past cultural empires |date=1934 |publisher=Oriental Cultural Association |location=Japan |page=592 |url=https://books.google.com/books?id=bYHLa7bOSwAC |access-date=23 May 2024 |language=Ja}}}}

• Tokugawa ordered his general, Sakakibara Yasumasa, to lead an army from Kantō to camp in Seta, Ōmi Province as a means of showing off and intimidating the bureaucratic faction which was led by Ishida Mitsunari, because Ōmi was the traditional hometown of the Mitsunari clan.{{cite book |author1=Kazuo Murayama |title=名将言行録|trans-title=meishō genkō-roku/A record of famous generals’ words and deeds |date=1991 |publisher=講談社 |isbn=4062921774 |quote=Arai Hakuseki 藩翰譜 (clan records); Shigezane Okaya (1835-1920)}}

• In 1599, a riot occurred within the Ukita clan when several of Ukita clan vassals, including Togawa Tatsuyasu,{{cite book |title=日本戦史‧関原役: 第五篇| trans-title=Japanese War History‧Sekihara Role: Part 5 |chapter=2}}[{{NDLDC|771069/115}}] Sadatsuna Oka and others, rebelled against Hideie.{{cite book|author=Yasumasa Onishi|title=「豊臣政権の貴公子」宇喜多秀家|trans-title=Noble Prince of the Toyotomi Administration Hideie Ukita|publisher=Kadokawa |series=角川新書|date=2019}} At first, Ieyasu sent his general Sakakibara Yasumasa to mediate the disputes between Ukita Hideie and his various rebellious vassals. However, the situation was not resolved for a long time so Ieyasu ordered Yasumasa to return to his post and decided to resolve the case himself. Ieyasu managed to solve the case and averted a civil war between two factions. However, in the aftermath of this incident many of Hideie retainers such as Sakazaki Naomori changed their allegiance to Tokugawa Ieyasu and left Hideie. These defections caused massive setbacks for the Ukita clan politically and militarily, while strengthening Ieyasu.{{cite book |author1=大西泰正 |title=豊臣期の宇喜多氏と宇喜多秀家 |date=2010 |isbn=9784872946123 |publisher=岩田書院 |page=99 |url=https://books.google.com/books?id=0tlMAQAAIAAJ |access-date=10 May 2024 |language=Ja}}

• In April 1599, Ieyasu cited Hideyoshi's will as pretext for him to review the decision regarding the Mōri clan territories that Mitsunari had pushed through, and pressed Mōri Terumoto to allocate part of Nagato Province and Suō Province to Mōri Hidemoto.{{sfn|Mitsunari|2016|pp=250–251}} In June, Ieyasu's manifesto to curtail Terumoto's domains was implemented, as Hidemoto had been given the former Mōri Motokiyo territory of Nagato, Yoshiki District in Suō, Aki, and Bingo, leaving Kikkawa Hiroie's territory intact, and returned Kobayakawa Takakage's estate to Terumoto.{{sfn|Mitsunari|2016|p=251}}

• Ieyasu had his general and diplomat, Ii Naomasa, establish contact with the scions of Kuroda clan, Kuroda Yoshitaka and Kuroda Nagamasa, and gained their political support.{{sfn|Noda|2007}}

• On September 12, 1599, when Ieyasu returned to Fushimi castle from Osaka castle, there was an alleged assassination attempt by three Toyotomi Hideyoshi vassals named Katsuhisa Hijikata, Asano Nagamasa, and Ōno Harunaga. Their attempt to assassinate Ieyasu failed due to Ieyasu's tight security and bodyguards. When they were apprehended, further investigation also linked the assassination attempt with Maeda Toshimasa, son of Maeda Toshiie. Ieyasu consulted with Honda Masanobu about the proper punishment for each conspirator, Masanobu instead advised Ieyasu to show leinency towards the three perpetrators. In the end, Ieyasu accepted Masanobu's counsel and decided that he would not execute them, in exchange, he placed Hijikata and Katsuhisa on house arrest on northern side of the Kantō region. Meanwhile, Nagamasa was given a far more lenient punishment than his compatriots by only being ordered to move his residence, Musashi Fuchū, as Ieyasu saw Nagamasa had an important political position in the government. As for Toshimasa, Ieyasu prepared a harsh punishment and he prepared to dispatch his army to Kaga in order to subjugate Toshinaga, who was one of the Five Elders. In response, Toshinaga sent his subordinate, Nagatomo Yokoyama, to Ieyasu and immediately apologized to Ieyasu. Furthermore, he sent his mother, Hoshunin, as a hostage to Edo, and arranged for his adopted heir, Toshitsune, to marry Hidetada's daughter, Tamahime. Due to those four men later supporting Ieyasu in the Sekigahara war against Mitsunari, modern historian Daimon Watanabe saw Tokugawa's lenient attitude towards his would-be assassins as a political move to gather more allies to would support him in the future war.{{cite web |author1=Daimon Watanabe |title=徳川家康暗殺未遂事件とその後の経過…政治的影響を考慮した家康はどんな処置を下したのか？ |trans-title=The assassination attempt of Ieyasu Tokugawa and its aftermath...What measures did Ieyasu take in consideration of the political impact? |url=https://sengoku-his.com/428 |website=sengoku-his.com |access-date=28 May 2024 |language=Ja |date=2023 |quote=Referencing Goki Mizuno “Re-criticism of the Kaga Conquest” fictional theory” (Research Collection History and Culture No. 8, 2021)}}

• Tokugawa married his sixth son, Matsudaira Tadateru, to Irohahime, the first daughter of Date Masamune.{{cite book |author1=Satoshi Okamoto (岡本哲志) |title=江戸→TOKYO なりたちの教科書３ 東京の基盤をつくった「武家屋敷物語」 |date=2018 |publisher=淡交社 |page=23 |url=https://books.google.com/books?id=6HjcEAAAQBAJ |access-date=29 May 2024 |language=Ja}}

Ieyasu also gained support from Mogami Yoshiaki, brother-in-law of Masamune and a powerful eastern daimyo, who had held a grudge against the Toyotomi clan since Hideyoshi executed his daughter in the Hidetsugu Incident of 1595.{{sfn|Kanie|1990|p=443}} Hidetsugu had been accused of treason and forced to commit seppuku at Mount Kōya. In the aftermath of this incident, his entire family was also executed at Sanjogawara. Yoshiaki's daughter, Komahime, was only 15 years old and had recently married Hidetsugu, was executed as a result. Yoshiaki begged for her life to be spared as she hadn't even met Hidetsugu yet, but his request was refused. Komahime was beheaded along with the others, and her body dumped in the Sanjogawara River. As result of the execution, Yoshiaki's wife, Osaki-dono, was struck with deep grief by the sudden death of her daughter and died on August 16. After this, Yoshiaki grew closer to Ieyasu and became one of his strongest supporters.{{cite web |author1=Kenji Matsuo (松尾剛次) |title=伊達と上杉の宿敵「最上義光」...梟雄と語られてきた戦国大名の知られざる素顔 |trans-title=The sworn enemy of the Date and Uesugi clans, "Mogami Yoshiaki"... The unknown face of the Sengoku lord who was described as a warlord |url=https://rekishikaido.php.co.jp/detail/10839 |website=Rekishikaido |publisher=PHPオンライン |access-date=14 June 2024 |language=Ja |date=2024}}

• Another incident occurred in 1595 with the Shimazu clan, when Shimazu Tadatsune, the third son of Shimazu Yoshihiro and heir to the main Shimazu family, assassinated a clan's chief vassal named Ijuin Tadamune. The background to this incident seems to be that Tadamune, who was on close terms with Ishida Mitsunari, had infringed on the Shimazu clan's domain. However, the incident did not end there, and Tadamune's eldest son, Ijuin Tadamasa, started a rebellion. As the civil war reached deadlock, Ieyasu mediated the two sides, which resulted in Tadamasa surrendering in March 1600.{{cite web |author1=pinon |title=「島津豊久」は父・家久と伯父・義弘の薫陶を受けた名将であった！ |trans-title=Shimazu Toyohisa was a famous general who was mentored by his father, Iehisa, and his uncle, Yoshihiro! |url=https://sengoku-his.com/102 |website=戦国ヒストリー |publisher=sengoku-his.com |access-date=11 June 2024 |language=Ja |date=2024 |quote=Kirino Sakujin (関ヶ原島津退き口―敵中突破三〇〇里― / Shimazu's Retreat at Sekigahara: Breaking Through Enemy Lines 300 Miles (Gakken Publishing, 2010); Niina Kazuhito(薩摩島津氏 / Satsuma Shimazu Clan) (Ebisu Kosho Publishing, 2014); Niina Kazuhito (島津家久・豊久父子と日向国 / Shimazu Iehisa and Toyohisa, Father and Son, and Hyuga Province ) (Miyazaki Prefecture, 2017); Niina Kazuhito (「不屈の両殿」島津義久・義弘　関ヶ原後も生き抜いた才智と武勇 / Shimazu Yoshihisa and Yoshihiro: The "Indomitable Princes" – The Wisdom and Bravery that Survived After Sekigahara) (Kadokawa、2021年)}}

File:Kabuto Tokugawa Ieyasu.jpg (helmet) of Tokugawa Ieyasu]]

{{Main|Siege of Shiroishi|Siege of Hasedō|Battle of Gifu Castle|Siege of Fushimi|Siege of Ueda}}

Meanwhile, opposition to Ieyasu centered around Ishida Mitsunari, one of Hideyoshi's Go-Bugyō, or top administrators of Hideyoshi's government, and a powerful daimyo who was not one of the regents. Mitsunari plotted Ieyasu's death and news of this plot reached some of Ieyasu's generals. They attempted to kill Mitsunari but he fled and gained protection from Ieyasu. It is not clear why Ieyasu protected a powerful enemy from his own men, but Ieyasu was a master strategist and may have concluded that he would be better off with Mitsunari leading the enemy army rather than one of the more legitimate regents.Sadler, p. 187

Nearly all of Japan's daimyo and samurai were now split into two factions; the Western Army (Mitsunari's group) and the Eastern Army (Ieyasu's group). Ieyasu had the support of the anti-Mitsunari group, and formed them into his potential allies. Ieyasu's allies were Katō Kiyomasa, Fukushima Masanori, Mogami Yoshiaki, Hachisuka Iemasa, the Kuroda clan, the Hosokawa clan and many daimyo from eastern Japan. Mitsunari had allied himself with three other regents: Ukita Hideie, Mōri Terumoto, and Uesugi Kagekatsu, as well as with Ōtani Yoshitsugu, the Chosokabe clan, the Shimazu clan and many daimyo from the western end of Honshū.{{Citation needed|date=March 2020}}

War became imminent when Uesugi Kagekatsu, one of Hideyoshi's appointed regents, defied Ieyasu by building up his military at Aizu. When Ieyasu officially condemned him and demanded that he come to Kyoto to explain himself, Kagekatsu's chief advisor, Naoe Kanetsugu, responded with a counter-condemnation that mocked Ieyasu's abuses and violations of Hideyoshi's rules. This infuriated Ieyasu.

In July 1600, Ieyasu was back in Edo and his allies moved their armies to defeat the Uesugi clan, which were accused of planning to revolt against the Toyotomi administration. On September 8, Ieyasu received information that Mitsunari had captured Fushimi castle and his allies had moved their army against Ieyasu. Ieyasu held a meeting with the Eastern Army daimyo, and they agreed to follow Ieyasu. Later, on September 15, Mitsunari's Western army arrived at Ogaki Castle. On September 29, Ieyasu's Eastern Army took Gifu Castle. On October 7, Ieyasu and his allies marched along the Tōkaidō, while his son Hidetada went along through Nakasendō with 38,000 soldiers (a battle against Sanada Masayuki in Shinano Province delayed Hidetada's forces, and they did not arrive in time for the main Battle of Sekigahara).{{cite web |author1=Hamada Koichiro; University of Hyogo, Himeji Dokkyo University |title=「どうする家康」徳川家康の秀忠への怒りを解かせた、徳川四天王・榊原康政の直言 |trans-title=“What should Ieyasu do?” The direct words of Yasumasa Sakakibara, one of the Four Heavenly Kings of Tokugawa, that relieved Tokugawa Ieyasu of his anger towards Hidetada. |url=https://sengoku-his.com/2155 |website=sengoku-his.com |access-date=26 May 2024 |language=Ja |date=2023}}

{{Main|Battle of Sekigahara}}

File:Sekigahara Tokugawa's Final Encampment.jpg

The Battle of Sekigahara was the biggest battle as well as one of the most important in Japanese feudal history. It began on October 21, 1600. The Eastern Army led by Tokugawa Ieyasu initially numbered 75,000 men, with the Western Army at a strength of 120,000 men under Ishida Mitsunari. Ieyasu had also secretly acquired a supply of arquebuses.

Knowing that the Tokugawa forces were heading towards Osaka, Mitsunari decided to abandon his positions and marched to Sekigahara. Even though the Western Army had tremendous tactical advantages, Ieyasu had already been in contact with many of the daimyo in the Western Army for months, promising them land and leniency after the battle should they switch sides. Ieyasu had also secretly communicated with Toyotomi Hideyoshi's nephew, Kobayakawa Hideaki. With a total of 170,000 soldiers facing each other, the Battle of Sekigahara ensued and ended with an overwhelming Tokugawa victory.Titsingh, Isaac (1834). [Siyun-sai Rin-siyo/Hayashi Gahō, 1652], Nipon o daï itsi ran; ou, [https://books.google.com/books?id=18oNAAAAIAAJ Annales des empereurs du Japon]. Paris: Oriental Translation Fund of Great Britain and Ireland, p. 405. At the conclusion of the battle, Ieyasu marched to Osaka castle, where Mōri Terumoto, the grand commander of Western army, surrendered to him.{{harvtxt|Yano Kazutada |1926|pp=590~593}}

The Western bloc quickly collapsed, and over the next few days Ishida Mitsunari and other western leaders such as Konishi Yukinaga and Ankokuji Ekei were captured and executed.Turnbull, Steven: The Samurai: a Military History (London, 1977), Osprey Publishing London, pp. 245–246 However, Ieyasu was angry at his son Hidetada, whose army was late to arrive, leading to an unexpectedly long siege against Ueda castle. Sakakibara Yasumasa offered an explanation and testified in defense of Hidetada. Meanwhile, Ieyasu pardoned his enemies who defended Ueda castle, including Sanada Masayuki and Sanada Yukimura, at the behest of Ii Naomasa and Sanada Nobuyuki.{{sfn|野田|2007|p=典拠史料は「真田家武功口上之覚」（『真田家文書』中巻、1982年}}

Ieyasu redistributed the domain fiefs of all the daimyo lords who supported him during the war, such as increasing Ii Naomasa domain to 180,000 koku.{{cite book |author1=川村 真二 |title=徳川四天王 家康に天下を取らせた男たち |date=2014 |publisher=PHP研究所 |isbn=978-4569761930 |page=54 |language=ja }} Ikeda Terumasa's to 520,000 Koku.{{cite book |author1=Arthur Lindsay Sadler |author1-link=Arthur Lindsay Sadler |title=Japanese Tea Ceremony Cha-No-Yu |date=2011 |publisher=Tuttle Publishing |isbn=9781462903597 |page=https://books.google.co.id/books?id=pS_RAgAAQBAJ&newbks= |url=https://books.google.com/books?id=pS_RAgAAQBAJ |access-date=29 April 2024 |language=En}} Tōdō Takatora got a new domain which was assessed at a total of 200,000 koku, Yuki Hideyasu went from 101,000 to 569,000 koku, Matsudaira Tadayoshi went from 100,000 to 520,000 koku, Gamō Hideyuki increased from 180,000 to 600,000 koku, Maeda Toshinaga went from 835,000 to 1,100,000 koku, Katō Kiyomasa's domain grew from 195,000 to 515,000 koku, and Kuroda Nagamasa's grew from 180,000 to 523,000 koku. Meanwhile, Fukushima Masanori had his 200,000 koku domain increased to 498,000 in Aki, Hiroshima. Ieyasu also promoted many of his own hereditary vassals to domains of at least 10,000 koku for their stipends.{{cite web |author1=Watanabe Daimon |title=関ヶ原合戦後、徳川家康が東軍諸将を大幅に加増し、厚遇した当たり前の理由 |trans-title=The obvious reason why Tokugawa Ieyasu gave large increases to Eastern Army generals and treated them well after the Battle of Sekigahara |url=https://news.yahoo.co.jp/expert/articles/8ab5882df39ff56f4d9472da34df1f7d3afbcf72 |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=2 June 2024 |language=Ja |date=2023}} After the battle, Ieyasu left some Western Army daimyo unharmed, such as the Shimazu clan, but others were completely destroyed. Toyotomi Hideyori (the son of Hideyoshi) lost most of his territory which was under management of western daimyo, and was degraded to an ordinary daimyo, rather than a Sesshō or Kampaku (regent) of the Japanese empire. In later years, the vassals who had pledged allegiance to Ieyasu before Sekigahara became known as the fudai daimyō, while those who pledged allegiance to him after the battle (after his power was unquestioned) were known as tozama daimyō. Tozama daimyō were considered inferior to fudai daimyō.{{Citation needed|date=March 2020}} This redistribution of domains was done verbally, instead of by formal letter of intent. Historian Watanabe Daimon suspected this was because Ieyasu was still wary of the existence of Toyotomi clan which had been inherited by Toyotomi Hideyori.

On September 20, Ieyasu entered Otsu castle, where he welcomed and met with Kyōnyo, the head of Hongan-ji temple at that time, with Kanamori Nagachika as an intermediary.{{sfn|Ueba|2005|p=178-180}}{{sfn|Ōkuwa|2013|p=69-71,154}}{{harvtxt|同朋大学仏教文化研究所|2013|pp=125–129,217–218,274}}{{harvtxt|本願寺史料研究所|2015|pp=13–14}} He met Ieyasu again the following year (1601), and Ieyasu visited Kyōnyo on July 5 and August 16. However, for the rest of 1601, the relationship between them grew worse as Kyōnyo was accused of pro-Mitsunari sympathy.{{harvtxt|同朋大学仏教文化研究所|2013|pp=129–130}}{{harvtxt|本願寺史料研究所|2015|pp=14–15}} It was only in February 1602 that the communication between Ieyasu with Kyōnyo opened again. This was after the intercession from aide Honda Masanobu, where the three of them discussed the condition of the Hongan-ji temple development after the split of the sect into two factions. Ieyasu worried the strife within the temple could affect the stability of Japan after the Sekigahara war.{{sfn|Ōkuwa|2013|pp=71–72}}

In 1602, Ieyasu changed his surname from "Minamoto" to "Fujiwara". The reason for this changing was because Emperor Go-Yōzei wanted to appoint Ieyasu to be a court noble. However, there was no precedent in the Tokugawa bloodline as the Minamoto clan which Ieyasu ancestry claimed, was a samurai clan rather than a noble family. To resolve this problem, a fabrication was made that said the Tokugawa clan also descended from Fujiwara clan, which was a noble family. By changing his name to Fujiwara, Ieyasu was able to be appointed to the rank of Junior Fifth Rank.{{efn|This predecent was found in a letter from Konoe Motohisa dated February 20, 1602 (Keicho 7). The circumstances surrounding Ieyasu's change of surname were similar with a previous case, when he changed from "Matsudaira" to "Tokugawa" in a letter dated December 3, 1566 (Eiroku 9) from Maehisa Konoe (Konoe Family Documents).{{cite web |author1=Watanabe Daimon |title=徳川家康の本姓は源氏ではなく、なぜ藤原氏だったのか |url=https://news.yahoo.co.jp/expert/articles/a15d126086c30b5c775b22184b2fa5d51dc9918e |website=yahoo.co.jp/expert |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=2 June 2024 |language=Ja}}}}

{{Main|Tokugawa shogunate}}

File:Shogun-Tokugawa-Ieyasu.png of Tokugawa Ieyasu]]

On March 24, 1603, Tokugawa Ieyasu received the title of shōgun from Emperor Go-Yōzei.Titsingh, Isaac (1822). Illustrations of Japan. London: Ackerman, p. 409. Ieyasu was 60 years old and had outlasted all the other great men of his times: Oda Nobunaga, Takeda Shingen, Toyotomi Hideyoshi, and Uesugi Kenshin. As shōgun, he used his remaining years to create and solidify the Tokugawa shogunate, which ushered in the Edo period, and was the third shogunal government (after the Kamakura and the Ashikaga). He claimed descent from the Minamoto clan who had founded the Kamakura shogunate, by way of the Nitta clan. His descendants would marry into the Taira clan and the Fujiwara clan.

Following a well established Japanese pattern, Ieyasu abdicated his official position as shōgun in 1605. His successor was his son and heir, Tokugawa Hidetada. There may have been several factors that contributed to his decision, including his desire to avoid being tied up in ceremonial duties, to make it harder for his enemies to attack his real power center, and to secure a smoother succession for his son.{{cite book

|last=Van Wolferen

|first=Karel

|author-link = Karel van Wolferen

|title=The Enigma of Japanese Power: People and Politics in a Stateless Nation

|isbn=0-679-72802-3

|year=1990

|publisher=Vintage Books

|location=New York|page=28

}}

In 1604, Tōdō Takatora and Date Masamune advised the Shogunate government to introduce a rule across Japan that each feudal lord was obliged to maintain a residence in Edo, the capital of the shogunate, which Ieyasu immediately accepted and implemented officially.{{harvtxt|Toshio G. Tsukahira |1966 |p=48}}

{{Main|Edo Castle}}

File:Edo P detail.jpg from a 17th-century painting]]

From 1605 onwards, Ieyasu, who had retired from the official position of shogun and became a {{nihongo|retired shōgun|大御所|ōgosho}}, remained the effective ruler of Japan until his death. Ieyasu retired to Sunpu Castle in Sunpu, but he also supervised the building of Edo Castle, a massive construction project which lasted for the rest of Ieyasu's life. The result was the largest castle in all of Japan. The cost of building the castle was borne by all the other daimyo, while Ieyasu reaped the benefits. The central donjon, or tenshu, burned in the 1657 Meireki fire. Today, the Imperial Palace stands on the site of the castle.{{Cite web|title=Imperial Palace {{!}} Tokyo, Japan Attractions|url=https://www.lonelyplanet.com/japan/tokyo/attractions/imperial-palace/a/poi-sig/1238764/356817|access-date=2021-08-11|website=Lonely Planet|language=en}}

Edo became the center of political power and the de facto capital of Japan, although the historic capital of Kyoto remained the de jure capital as the seat of the emperor.Sansom, George. A History of Japan: 1615–1867, p. 114.Gordon, Andrew. (2003). A Modern History of Japan from Tokugawa Times to the Present, p. 23. Furthermore, Ieyasu had the Imperial Court appoint his eldest remaining son, Hidetada, as Shogun, announcing to the world that the position of shogun would be hereditary to the Tokugawa clan from then on. At the same time, he requested Toyotomi Hideyori meet the new shogun, but Hideyori refused. In the end, the matter was resolved by sending his sixth son, Matsudaira Tadateru to Osaka Castle. At the same time, the next generation of Tokugawa clan vassals, including Ii Naotaka and Itakura Shigemasa, were also appointed.{{Sfn|Murakawa|2013|pp=120–121}}

In 1608, Ieyasu assigned control of the Tsu Domain{{sfn|Nakayama|2015}}{{cite book |author1=Yuji Yamada |translator=Atsuko Oda |title=The Ninja Book : The New Mansenshukai |date=2017 |publisher=Mie University Facultyof Humanities, Law and Economics |url=https://books.google.com/books?id=2FwUDgAAQBAJ |access-date=11 May 2024 |language=En}}{{cite book |last1=Oishi |first1=Gaku |title=江戸五百藩-ご当地藩のすべてがわかる |date=2020 |publisher=Chuokoron-Shinsha |isbn= 978-4128001354}}{{in lang|ja}} to Takatora. It was reported that the landholdings which Takatora received in Iga province had previously belonged to a lord named Tsutsui Sadatsugu. Ieyasu stripped Tsutsui Sadatsugu of ownership rights before giving them to Takatora.{{Sfn|Tatsuo|2018|p=60}} The initial pretext was Sadatsugu's sloppy governance of the domain{{cite web|url=http://www.ict.ne.jp/~uenojyo/ |title=Iga Ueno Castle homepage |access-date=2007-04-09 |date=2002-04-09 |work=Iga Ueno Castle|language=Japanese}} however, historians have argued that the real reason was because Sadatsugu behaved suspiciously by visiting Toyotomi Hideyori at Osaka Castle, without approval of the shogun, while the land which Sadatsugu occupied was considered to be an important military strategic location.{{sfn|籔|1985|pp=213–214}} Furthermore, it is thought that Ieyasu expropriated the land and gave it to the Todo clan as political strategy against the Toyotomi clan, even though he was a patron of the Toyotomi family, Tōdō Takatora was considered a close ally of Ieyasu. Thus by putting him in control of portions of Iga province, the influence of the shogunate could be expanded to more strategic locations without directly provoking the Toyotomi faction in Osaka.{{Sfn|Tatsuo|2018|p=60}}

In 1611, (Keicho 16), Ieyasu, at the head of 50,000 men, visited Kyoto to witness the enthronement of Emperor Go-Mizunoo. While in Kyoto, Ieyasu ordered the remodeling of the Imperial Court, buildings, and forced the remaining western daimyo to sign an oath of fealty to him.{{Citation needed|date=March 2020}} On April 12, Ieyasu presented three articles of legislation to the daimyo in Kyoto. These Three Laws, as they were called, referred to the first shogun's set of laws and those that signed would strictly abide by the laws issued by the shogunate from then on. Second, the lords swore to not conceal those who disobeyed the shogun's orders, and third: to not hide or give shelter to any enemy of the state. 22 daimyo from the Hokuriku region and Western provinces agreed to the three articles of legislation and submitted an oath. Daimyo from Oshu and Kanto were not included in this list, because they were engaged in the construction of Edo Castle and did not come to Kyoto. In January of the following year, 11 major feudal lords from Oshu and Kanto swore to the Three Laws. 50 small and medium-sized fudai and tozama feudal lords also swore to the Three Laws, and Ieyasu succeeded in making all the feudal lords in the country his vassals.

Ieyasu did not have Hideyori work on national construction, nor did he have him swear to the Three Laws. Watanabe Daimon saw that the Three Laws issued by Ieyasu was a maneuver to isolate Hideyori politically by making all other influential daimyo lords obey him.{{cite web |author1=Watanabe Daimon |title=徳川家康が諸大名を臣従させ、豊臣秀頼を孤立させた巧妙な作戦 |url=https://news.yahoo.co.jp/expert/articles/cc0126363506d303d57b216f46b2994e94dcbd66 |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=3 June 2024 |language=Ja |quote=Watanabe Daimon, "Tokugawa Ieyasu: Full of Misunderstandings" (Gentosha Shinsho, 2022)}}

In 1613, he composed the {{Nihongo||公家諸法度|Kuge shohatto}}, a document which put the court daimyo under strict supervision, leaving them as mere ceremonial figureheads.{{Cite web|last=Yu|first=A. C.|title=Kinchu narabini kuge shohatto (Law on the emperor and the court nobles) |url=https://www.japanese-wiki-corpus.org/history/Kinchu%20narabini%20kuge%20shohatto%20(Law%20on%20the%20emperor%20and%20the%20court%20nobles).html|access-date=2021-04-06|website=www.japanese-wiki-corpus.org}}

In 1615, Ieyasu prepared the {{Nihongo||武家諸法度|Buke shohatto}}, a document setting out the future of the Tokugawa regime.{{Cite web|title=Japan – The bakuhan system|url=https://www.britannica.com/place/Japan|website=Encyclopedia Britannica|language=en|access-date=2020-05-19}}

{{Main|History of Roman Catholicism in Japan}}

File:William-Adams-before-Shogun-Tokugawa-Ieyasu.png before shogun Tokugawa Ieyasu]]

File:KingJamesLetter.jpg to ogosho Tokugawa Ieyasu in 1613]]

As Ōgosho, Ieyasu also supervised diplomatic affairs with the Netherlands, Spain, and England. Ieyasu chose to distance Japan from European influence starting in 1609, although the shogunate still granted preferential trading rights to the Dutch East India Company and permitted them to maintain a "factory" for trading purposes.{{Citation needed|date=March 2020}}

From 1605 until his death, Ieyasu frequently consulted English shipwright and pilot, William Adams.Milton, Giles. Samurai William: The Englishman Who Opened Japan. New York: Farrar, Straus, and Giroux, 2003. Adams, a Protestant{{cite book | last=Nelson | first=J.K. | title=A Year in the Life of a Shinto Shrine | publisher=University of Washington Press | year=2015 | isbn=978-0-295-99769-8 | url=https://books.google.com/books?id=2ijECgAAQBAJ&pg=PA16 | access-date=2023-03-01 | page=16}} fluent in Japanese, assisted the shogunate in negotiating trading relations, but was cited by members of the competing Jesuit and Spanish-sponsored mendicant orders as an obstacle to improved relations between Ieyasu and the Roman Catholic Church.Nutail, Zelia (1906). [https://books.google.com/books?id=1NACAAAAYAAJ The Earliest Historical Relations Between Mexico and Japan]. Berkeley: University of California Press, pp. 6–45.{{cite book |last=Milton |first=Giles |author-link=Giles Milton |title=Samurai William : the Englishman Who Opened Japan |date=2003 |url=https://books.google.com/books?id=RfJ0w6Dt8TAC&pg=PT265 |page=265|publisher=Farrar, Straus and Giroux |isbn=978-0374706234 }} Quoting Le P. Valentin Carvalho, S.J.{{sfn|Murdoch|Yamagata|1903|p=500}}

In 1612, the Nossa Senhora da Graça incident occurred in Nagasaki, where the bugyō official of Sakai Hasegawa Fujihiro had trouble with Portuguese captain André Pessoa.{{sfn|Boxer|1951|pp=272–273}} The conflict escalated when Pessoa and the merchants from Macau petitioned Ieyasu directly to complain about Hasegawa and Murayama Tōan, a magistrate of Ieyasu. When the Jesuits learned of this affair, they were horrified when they found out about Pessoa's petition as they knew that Hasegawa's sister Onatsu was a favorite concubine of Ieyasu.{{sfn|Boxer|1948|p=58}}

Later, Pessoa withdrew his petition when he learned of the internal politics of the shogunate. However, Fujihiro refused to forgive Pessoa's petition.{{sfn|Boxer|1948|p=276}} Fujihiro encouraged Arima Harunobu, who wanted to retaliate for the prior Macau incident, to petition Ieyasu for the capture of Pessoa and the seizure of his merchant ship. Ieyasu, who had entrusted Harunobu with the purchase of agarwood, was initially concerned that a retaliatory act would cut off trade with Portuguese ships. Thus, the shogunate took a lenient attitude to Pessoa, as Honda Masazumi, with authorization from Ieyasu, gave Pessoa's envoy written assurances that Japanese sailors would be forbidden to travel to Macau, and any who did could be handled according to Portuguese laws.{{sfnm|Boxer|1951|1p=274|Boxer|1948|2p=57}} However, Ieyasu later gave Harunobu permission to capture Pessoa after he had been guaranteed that Manila ships of Spanish merchants would be able to replenish raw silk and other goods carried by Portuguese ships and also expected Dutch ships to continue arriving.{{Cite web|url=http://www.historist.jp/word_j_no/entry/036263/ |title=ノッサ・セニョーラ・ダ・グラッサ号事件(ノッサ・セニョーラ・ダ・グラッサごうじけん) / 日本史 -の-｜ヒストリスト［Historist］−歴史と教科書の山川出版社の情報メディア− |trans-title=Nossa Senhora da Graça incident (Nossa Senhora da Graça incident) |publisher=Yamakawa Publishing|date=2016 |access-date=2020-11-18}} Then Ieyasu gave authorization to Hasegawa and Arima Harunobu.{{sfn|Boxer|1948|p=58}}

After several days of battle, which resulted in Pessoa's death, the remaining Portuguese merchants and missionaries were increasingly concerned about their fates, especially since Ieyasu had personally ordered their execution. Harunobu, who was Catholic, interceded on behalf of the Jesuits. Ieyasu changed his decision and the merchants were allowed to leave for Macau with their property. Ieyasu's Jesuit translator, João Rodrigues Tçuzu, was replaced by William Adams.{{sfn|Milton|2011|loc=[https://books.google.com/books?id=jZqNl1GnkoYC&pg=PT38]}} Ieyasu then expelled João Rodrigues from Japan.{{Cite book|author=Takase Koichiro |title=キリシタン時代の貿易と外交 |trans-title=Trade and diplomacy in the Christian era|publisher=Yagi Shoten |year=2002 |isbn=4840620202 |pages=383–384}}

In 1612, the Okamoto Daihachi incident occurred where Okamoto Daihachi (岡本大八, baptismal name Paulo), a Christian aide to the rōjū Honda Masazumi, and Arima Harunobu, were implicated in series of crimes including bribery, conspiracy, forgery, and attempt to murder Hasegawa Fujihiro. Ieyasu was angered when he heard that Catholic followers had gathered at Okamoto's execution to offer prayers and sing hymns.{{sfn|Murdoch|Yamagata|1903|p=498}}

in 1614, Ieyasu was sufficiently concerned about Spanish territorial ambitions and signed the Christian Expulsion Edict. The edict banned the practice of Christianity and led to the expulsion of all foreign missionaries although some smaller Dutch trading operations remained in Nagasaki.{{cite journal

| last = Mullins

| first = Mark R.

| year = 1990

| title = Japanese Pentecostalism and the World of the Dead: a Study of Cultural Adaptation in Iesu no Mitama Kyokai

| journal = Japanese Journal of Religious Studies

| volume = 17

| issue = 4

| pages = 353–374 | doi = 10.18874/jjrs.17.4.1990.353-374

| doi-access = free

}}

{{Main|Siege of Osaka}}

File:Hokoji(rushanabutsu).jpg built by Hideyori]]

The last remaining threat to Ieyasu's rule was Toyotomi Hideyori, the son and rightful heir to Hideyoshi. He was now a young daimyo living in Osaka Castle. Many samurai who opposed Ieyasu rallied around Hideyori, claiming that he was the rightful ruler of Japan. Ieyasu found fault with the opening ceremony of a temple (Great Buddha of Kyoto) built by Hideyori; it was as if he prayed for Ieyasu's death and the ruin of the Tokugawa clan. Ieyasu ordered Hideyori to leave Osaka Castle, but those in the castle refused and summoned samurai to gather within the castle. Then in 1614, Ieysau besieged Osaka Castle.

Tokugawa forces, with a huge army led by Ieyasu and shōgun Tokugawa Hidetada, laid siege to Osaka Castle in what is now known as "the Winter Siege of Osaka". Eventually, the Tokugawa were able to force negotiations and an armistice after cannon fire threatened Hideyori's mother, Yodo-dono. However, once the treaty had been agreed on, the Tokugawa filled in the castle's outer moats with sand so their troops could walk across. Through this ploy, Tokugawa gained a huge tract of land through negotiation and deception that they could not have gained through siege and combat. Ieyasu returned to Sunpu Castle, but after Toyotomi Hideyori refused another order to leave Osaka, Ieyasu and his allied army of 155,000 soldiers attacked Osaka Castle again in "the Summer Siege of Osaka".

In late 1615, Osaka Castle fell and nearly all the defenders were killed, including Hideyori, his mother (Toyotomi Hideyoshi's widow, Yodo-dono), and his infant son. His wife, Senhime (a granddaughter of Ieyasu), pleaded to save Hideyori and Yodo-dono's lives. Ieyasu refused and either required them to commit seppuku, or killed both of them. Eventually, Senhime was sent back to the Tokugawa clan alive. With the Toyotomi line finally extinguished, no threats remained to the Tokugawa clan's domination of Japan.{{Citation needed|date=September 2021}}

File:The tomb of Tokugawa Ieyasu.JPG]]

After the conflict with Toyotomi Hideyori, Ieyasu implemented the Buke shohatto code, which stated that each daimyo lord was only allowed to possess one castle.{{cite web |author1=Watanabe Daimon |title=戦国大名の改易と徳川時代の幕開け…武家諸法度・一国一城令と、福島正則の改易事例 |trans-title=The demotion of feudal lords during the Sengoku period and the beginning of the Tokugawa period...The example of the demotion of Fukushima Masanori, and the Buke Shohatto and Ikkoku Ikjō Law |url=https://sengoku-his.com/2378 |website=sengoku-his |publisher=sengoku-his.com |access-date=19 June 2024 |language=Ja |date=2024}}

In 1616, Tokugawa Ieyasu died at the age of 73. The cause of death is thought to have been cancer or syphilis. The first Tokugawa shōgun was posthumously deified with the name Tōshō Daigongen ({{lang|ja|東照大權現}}), the "Great Gongen, Light of the East". (A Gongen is believed to be a buddha who has appeared on Earth in the shape of a kami to save sentient beings). In life, Ieyasu had expressed the wish to be deified after his death to protect his descendants from evil. His remains were buried at the Gongens' mausoleum at Kunōzan, Kunōzan Tōshō-gū ({{lang|ja|久能山東照宮}}). Many people believe that after the first anniversary of his death, his remains were reburied at Nikkō Shrine, Nikkō Tōshō-gū ({{lang|ja|日光東照宮}}), and that his remains are still there. Neither shrine has offered to open the graves, and the location of Ieyasu's physical remains is still a mystery. The mausoleum's architectural style became known as gongen-zukuri, that is gongen-style.[http://www.aisf.or.jp/~jaanus/deta/g/gongenzukuri.htm JAANUS / Gongen-zukuri {{lang|ja|權現造}}]

He was first given the Buddhist name Tosho Dai-Gongen ({{lang|ja|東照大權現}}), then, after his death, it was changed to Hogo Onkokuin ({{lang|ja|法號安國院}}).{{Citation needed|date=March 2020}} During this time, the chief physician who cared for him, Sotetsu Katayama, diagnosed Ieyasu with stomach cancer. However, Ieyasu misinterpreted Katayama's diagnosis of his illness as a tapeworm infestation. Thus, he did not take the medicine Sotetsu had prepared, and instead continued his own method of therapy which he believed could cure his perceived tapeworm problem. This resulted in Ieyasu's health continually deteriorating.

Although his son, Hidetada, also warned him about his medical method, this only served to anger Ieyasu, who arrogantly overvalued his own knowledge in the medical field. This conflict over his medical care ended when Ieyasu exiled Sotetsu to the Shinshu Takashima Domain.{{Cite book|author=Shinoda Tatsuaki|title=Medical Records of 15 Generations of Tokugawa Shoguns |series=Shincho Shinsho|year=2005|isbn=978-4-10-610119-9}}{{Sfn|Miyamoto|1995}}

At the time of his death, Ieyasu had an estimated personal wealth of about 4 million koku, which extended to 8 million koku for the total of the Tokugawa clan. He also possessed about 42 tons of gold as the Tokugawa Shogunate had implemented the centralization of gold and silver mine ownership, unlike previous eras of government in Japan, in which possession of mine ownership was managed by local lords through the shogunate authorization.{{cite web |author1=Ōjirō Ōmura (大村大次郎) |title=日本史上最大の資産家は徳川家康だった！？ |url=https://rekishikaido.php.co.jp/detail/7050 |website=rekishikaido |publisher=PHPオンライン |access-date=12 June 2024 |pages=1–2 |language=Ja |date=2019}}

The Tokugawa shogunate would rule Japan for the next 260 years.

File:Tokugawa Ieyasu handprint.jpg]]

File:Ieyasu precepts.jpg on the secret of success in life drafted by Tokugawa Ieyasu from the collection of Nikkō Tōshō-gū]]

A historical evaluation of Ieyasu by Junji Mitsunari, a historian on the faculty at Kyushu University, has compared Ieyasu's upbringing to that of another Sengoku era leader, Mōri Terumoto. Mitsunari contrasted Terumoto's upbringing in the comfortable and stable domains of the Mōri clan, as opposed to the hardships Ieyasu faced during his childhood, in which he experienced instability in Mikawa province, spending much his youth as a hostage of other warlords; in his view these differences formed each leader's character, as reflected in the Sekigahara battle, where the indecisiveness of Terumoto cost the Western army greatly, while Ieyasu's bold decisions and his willingness to take risks gave him the edge during the war.{{Cite book|author=Junji Mitsunari |title=小早川隆景・秀秋 消え候わんとて、光増すと申す|date=2019 |publisher=ミネルヴァ書房 |series=ミネルヴァ日本評伝選|isbn=978-4623085972 |page=359}}

John T. Kuehn saw Ieyasu as being capable of complex long game strategies, both politically and militarily, as shown during his conflict against Ishida Mitsunari. Kuehn saw the Siege of Fushimi Castle as Ieyasu's deliberate strategy to sacrifice the castle and to bait Mitsunari into a set-piece battle, where his battle-hardened forces had an advantage over Mitsunari's forces.{{cite book |author1=John T. Kuehn |title=A Military History of Japan: From the Age of the Samurai to the 21st Century |date=2014 |publisher=Bloomsbury Publishing |location=US |isbn=978-1440803949 |pages=127–128 |url=https://books.google.com/books?id=luvEEAAAQBAJ&pg=PA127 |access-date=27 May 2024 |language=En}}

On the other hand, Kazuto Hongō has compared Ieyasu to Nobunaga as Ieyasu had insight to ensure the stability of the nation by the optimization and utilization of the abilities of his vassals rather than relying on the power of single individuals, as well as establishing succession systems.{{cite web |website=President Online（プレジデントオンライン） | author1=Kazuto Hongō (本郷和人) |title=だから江戸幕府は260年も続いた…東大教授が考える｢徳川家康にあって､織田信長になかったもの｣ |trans-title=That's why the Edo Shogunate lasted for 260 years... What a professor from Tokyo University thinks "Tokugawa Ieyasu had, and Oda Nobunaga didn't" |date=2023 |pages=1–4 |url=https://president.jp/articles/-/67467?page=1 |access-date=5 June 2024 |language=Ja}} Tetsuo Owada personally praised how Ieyasu managed to be quickly accepted by the citizens of the Kantō region and his ability to rule there without unrest after he transferred there, by continuing the lenient tax policies of the Hōjō clan in order to gain sympathy.{{cite web |author1=Tetsuo Owada |author1-link=Tetsuo Owada |title=北条氏康が志した「関東独立国家」...領民の支持を獲得できた民主政治とは? |trans-title=Hojo Ujiyasu aspired to an independent Kanto state... What was the democratic politics that gained the support of the people? |url=https://rekishikaido.php.co.jp/detail/10230?p=1 |pages=1–2 |access-date=11 June 2024 |language=Ja |date=2023}}

Hamada Koichiro from Himeji Dokkyo University has recorded that there is a systematic attempt of historiography studies in the aftermath of the Meiji Restoration to portray Ieyasu in a negative light as a "cunning old man" who used the temple's bell of Hokoji as casus belli to wage war against Hideyori. Koichiro saw this tendency of Ieyasu to resort to underhanded tactics as being quite justified to some extent for different reasons. One example was his attempt at suppressing the Mikawa Ikkō-ikki rebellion by breaking his promise of leniency to Jōdo Shinshū's followers in exchange for their surrender. However, Koichiro also points out that Ieyasu was also capable of bravery as showed by personally entering the battlefield during the rebellion, while also pointing out several anecdotes about Ieyasu as a youth showing promise as a capable military tactician when he still under the wing of the Imagawa clan.{{cite web |author1=Hamada Koichiro|publisher =University of Hyogo, Himeji Dokkyo University |title=徳川家康とはどのような武将だったのか？…非狸親父説は本当か？ |trans-title=What kind of military leader was Tokugawa Ieyasu? Is the raccoon "grandpa" theory true? |url=https://sengoku-his.com/1878 |access-date=26 May 2024 |language=Ja |date=2022}}

Ieyasu was capable of great loyalty: once he allied with Oda Nobunaga, he never went against him, and both leaders profited from their long alliance. He was known for being loyal towards his personal friends and vassals, whom he rewarded. Ieyasu was said to have a close friendship with his vassal Hattori Hanzō.

However, he also remembered those who had wronged him in the past. It is said that Ieyasu once executed a man who came within his power because he had insulted him when Ieyasu was young.{{Cite book|last1=Goethals|first1=George R.|url=https://books.google.com/books?id=kjLspnsZS4UC&q=ieyasu+executed+a+man+insulted+him+when+Ieyasu+was+young&pg=PA1550|title=Encyclopedia of leadership: A–E|last2=Sorenson|first2=Georgia|date=2004|publisher=Sage|isbn=978-0-7619-2597-2|language=en}}

According to professor Watanabe Daimon, one of the biggest strengths of Ieyasu's policies was his benevolence towards his subordinates and his capability to forgive his enemies and even his own generals who betrayed him during the Mikawa Ikkō-ikki uprising. This allowed him to gain the loyalty of the Mikawa samurai clans. As an example, during the battle of Mikatagahara, those who shielded Ieyasu and even gave their lives to allow his retreat were the ones who once fought against Ieyasu in the past and had been pardoned.{{cite web |author1=Watanabe Daimon |title=家康は根に持つ性格だったのか？それとも寛大な心を持つ人物だったのか |url=https://news.yahoo.co.jp/expert/articles/cb2e73b3bd7f66012fa5a7451307a18778df844e |website=yahoo.co.jp/expert/articles/ |publisher=渡邊大門 無断転載を禁じます。 © LY Corporation |access-date=3 June 2024 |language=Ja |date=2023}} Ieyasu also protected many former Takeda retainers from the wrath of Oda Nobunaga, who was known to harbour a bitter grudge towards the Takeda. He managed successfully to transform many of the retainers of the Takeda, Hōjō, and Imagawa clans —all whom he had defeated himself or helped to defeat—into loyal vassals.

At the same time, he was also ruthless when crossed. For example, he ordered the executions of his first wife and his eldest son, a son-in-law of Oda Nobunaga; Nobunaga was also an uncle of Hidetada's wife Oeyo.{{cite web|url=http://www.city.obama.fukui.jp/section/sec_sekaiisan/english/data/290.htm|title=Jyoukouji:The silk coloured portrait of wife of Takatsugu Kyogoku|date=May 6, 2011|access-date=February 15, 2018|url-status=dead|archive-url=https://web.archive.org/web/20110506142910/http://www.city.obama.fukui.jp/section/sec_sekaiisan/english/data/290.htm|archive-date=May 6, 2011}} According to George Sansom, Ieyasu was cruel, relentless and merciless in the elimination of Toyotomi survivors after the Siege of Osaka. For days, scores of men and women were hunted down and executed, including an eight-year-old son of Toyotomi Hideyori by a concubine, who was beheaded.{{cite book |last=Sansom |first=George |date=1963 |title=A History of Japan, 1615–1867 |url=https://archive.org/details/historyofjapan1600sansrich/page/8/mode/2up |location=Stanford |publisher=Stanford University Press |page=9 |isbn=9780804705264 |quote=The subsequent hunting down of the surviving defenders of Ōsaka was merciless. Day after day at least fifty or a hundred men were caught and killed, and soon their heads were exposed by the thousand on the road between Fushimi and Kyoto. Many tragic tales are told of the cruelty for which Ieyasu was responsible. The eight-year-old son of Hideyori by a concubine was decapitated on the public execution ground at Rokujō-Kawara. }} However, Ieyasu also known to be capable of forgiveness, such as how he gave pardon to Watanabe Moritsuna after he rebelled against Ieyasu during the Ikkō-ikki uprisings in Mikawa.{{cite book |author1=Carol Richmond Tsang |title=War and Faith |date=2007 |publisher=Harvard University Asia Center |isbn=9781684174577 |pages=200–234 |url=https://doi.org/10.1163/9781684174577_008 |access-date=27 May 2024 |language=En |chapter=From Peak to Defeat, 1554–1580|doi=10.1163/9781684174577_008 }}

Unlike Toyotomi Hideyoshi, he harbored no desires to conquer outside of Japan, only wanting to bring order, an end to open warfare, and to rule Japan.Frederic, Louis, Daily Life in Japan at the Time of the Samurai, 1185–1603, Charles E. Tuttle Company, Inc., Rutland, Vermont, 1973, p. 180

Ieyasu's favorite pastime was falconry. He regarded it as excellent training for a warrior.

{{blockquote|"When you go into the country hawking, you learn to understand the military spirit and also the hard life of the lower classes. You exercise your muscles and train your limbs. You have any amount of walking and running and become quite indifferent to heat and cold, and so you are little likely to suffer from any illness."Sadler, p. 344.}}

Ieyasu swam often; even late in his life he is reported to have swum in the moat of Edo Castle.{{cite book |last1=Turnbull |first1=Stephen |title=The Samurai Swordsman: Master of War |date=2008 |publisher=Frontline Books |isbn=978-1-4738-1793-7 |page=96 |url=https://books.google.com/books?id=YOV7BAAAQBAJ&pg=PA96 |language=en}}

Many sets of armors are said to have been used by Ieyasu, and at least 10 pieces of armor were used by Ieyasu during his life and recorded in history.

While warlords at the time preferred flashy armor and frontlets to show off their presence, the 'Hada Gusoku' armor used by Ieyasu in the Siege of Osaka is a jet black armor with very few decorations, and is said to represent Ieyasu's frugal personality.{{Cite web|title=【国宝・久能山東照宮展】 家康吉祥の具足、歯朶具足（しだぐそく）|trans-title=National Treasure Kunozan Toshogu Shrine Exhibition】 Ieyasu's auspicious armor, Shidagusoku (Hat Armor) |url=http://shizubi.jp/blog/1475/ |website=静岡市美術館 |access-date=2022-04-25 |language=ja}}

Like Hideyoshi, Ieyasu also presented armor to Europe, and there is a record of the "Moji-i Domaru Armor" at Ambras Castle in Austria being a gift from "the Emperor and Empress of Japan to Holy Roman Emperor Rudolf II." This armor has the same characteristics as the aforementioned "Hanairo Hinomaru-i Domaru Armor" and armor presented by Hidetada to King James I of England in 1613, and is believed to have been presented by Ieyasu between 1608 and 1612. The armor has the characters for {{Nihongo|World|天下|tenka}} on the front of the torso and left sleeve, and {{Nihongo|Peace|太平|taihei}} on the back of the torso and right sleeve, woven with red thread.{{cite book |title=家康の遺産-駿府御分物 |trans-title=eyasu's Legacy – Sunpu Imperial Propertypmpm

|date=1992 |publisher=Tokugawa Art Museum |url=https://ndlsearch.ndl.go.jp/books/R100000002-I000002304280 |access-date=9 June 2024 |language=Ja}}

Image:Tokugawa Ieyasu armor (replica) - Siege of Osaka Quadricentennial, Yukimura Sanada and Sengoku Samurai Warriors - Marunouchi Building, Tokyo, Japan - DSC01676.jpg|Replica of Ieyasu armor

Image:Shida gusoku of Tokugawa Ieyasu at Kunōzan Tōshō-gū.jpg|Armor of Tokugawa Ieyasu at Kunōzan Tōshō-gū

Image:Sunpu Castle Higashigomon 201015t.jpg|Golden Kindami gusoku armor of Ieyasu in Sunpu castle

image:Ambras Wunderkammer - Samurai Rüstung.jpg|Domaru armor with calligraphy

image:Sekigahara armour.jpg|Ieyasu's Western-style armor, believed to be worn by Ieyasu in the battle of Sekigahara

Life is like unto a long journey with a heavy burden. Let thy step be slow and steady, that thou stumble not. Persuade thyself that imperfection and inconvenience are the lot of natural mortals, and there will be no room for discontent, neither for despair. When ambitious desires arise in thy heart, recall the days of extremity thou hast passed through. Forbearance is the root of all quietness and assurance forever. Look upon the wrath of thy enemy. If thou only knowest what it is to conquer, and knowest not what it is to be defeated; woe unto thee, it will fare ill with thee. Find fault with thyself rather than with others.OldTokyo.com: [http://www.oldtokyo.com/toshogu-shrine.html Tōshō-gū Shrine]; American Forum for Global Education, [http://www.globaled.org/japanproject/lessons/lesson19_1.php JapanProject] {{Webarchive|url=https://web.archive.org/web/20121231062742/http://www.globaled.org/japanproject/lessons/lesson19_1.php |date=2012-12-31 }}; retrieved 2012-11-1.

The strong manly ones in life are those who understand the meaning of the word patience. Patience means restraining one's inclinations. There are seven emotions: joy, anger, anxiety, adoration, grief, fear, and hate, and if a man does not give way to these he can be called patient. I am not as strong as I might be, but I have long known and practiced patience. And if my descendants wish to be as I am, they must study patience.Storry, Richard. (1982). A History of Modern Japan, p. 60Thomas, J. E. (1996). Modern Japan: a social history since 1868, {{ISBN|0582259614}}, p. 4.

It is said that he fought, as a warrior or a general, in 90 battles.{{Citation needed|date=March 2020}}

He was interested in various kenjutsu skills, was a patron of the Yagyū Shinkage-ryū school, and also had them as his personal sword instructors.{{Citation needed|date=March 2020}}

File:100 views edo 049.jpg in 1857]]

Tokugawa Ieyasu was known for his devotion to the Jōdo-shū school of Buddhism throughout his life, having been born into the Matsudaira clan which followed Jōdō Buddhism. As a way of demonstrating his constant favor towards the sect, he moved his familial temple to the Zōjō-ji Temple in Edo and funded massive renovations to older Jōdo temples, including the head temple of Chion-in in Kyoto, while also financing the creation of several new temples. After confiding in the abbot of Zōjō-ji temple about wanting to become a deity to protect his country, he was given advice to regularly recite the nembutsu for the purpose of being born into Amida Buddha's Pure Land of Sukhavati, where he would be able to easily attain Buddhahood and protect his descendants and the entire nation of Japan. Ieyasu readily accepted this advice, and constantly repeated the nembutsu until the day he died. Despite his personal devotion to Jōdo-shū, Ieyasu was not a strict sectarian, placing his secretary Denchōrō, a Rinzai Zen monk, in charge of all religious affairs in Japan, Buddhist and Shinto alike.Eliot, Charles (1923). Japanese Buddhism (2nd ed.). London, England: Routledge & Kegan Faul Ltd. (published 1959). pp. 305–307.Victoria, Brian (1992). Zen at War (2nd ed.). Oxford, England: Rowman & Littlefield Publishers (published 2006).

Later in life he also took to scholarship and Confucianism, patronizing scholars like Hayashi Razan.Ponsonby-Fane, Richard. (1956). Kyoto: the Old Capital of Japan, 794–1969, p. 418.{{cite book |last=Goto-Jones |first=C. |url=https://books.google.com/books?id=4Pz49n0xRCgC&pg=PA38 |title=Political Philosophy in Japan: Nishida, the Kyoto School and co-prosperity |publisher=Taylor & Francis |year=2009 |isbn=978-1-134-30860-6 |series=Routledge/Leiden Series in Modern East Asian Politics, History and Media |page=38 |access-date=2023-03-01}}

While at first tolerant of Christianity,Leonard, Jonathan, Early Japan, Time-Life Books, New York, cl1968, p. 162 his attitude changed after 1613, and persecution of Christians sharply increased, with Ieyasu completely banning Catholicism in 1614.Sansom, G. B., The Western World and Japan, Charles E. Tuttle Company, Rutland and Tokyo, 1950, p. 132 The hostility of Ieyasu towards Catholics was shown when he replaced Jesuit translator João Rodrigues Tçuzu with William Adams in his court.{{sfn|Milton|2011|loc=[https://books.google.com/books?id=jZqNl1GnkoYC&pg=PT38]}} This change of attitude is believed to be due to the Okamoto Daihachi incident, where a Catholic daimyo and shogun's official were accused of a series of crimes.{{sfn|Murdoch|Yamagata|1903|p=498}} After the execution of Daihachi, Ieyasu reportedly said:

{{blockquote|If they see a condemned fellow, they run to him with joy, bow to him, and do him reverence. This they say is the essence of their belief. If this is not an evil law, what is it? They truly are the enemies of the Gods and of Buddha.{{sfn|Boxer|1951|p=318}}}}

• Senior First Rank (April 14, 1617; posthumously)

{{ahnentafel

|collapsed=yes |align=center | ref={{cite web|url=https://reichsarchiv.jp/%e5%ae%b6%e7%b3%bb%e3%83%aa%e3%82%b9%e3%83%88/%e5%be%b3%e5%b7%9d%ef%bc%88%e5%be%b7%e5%b7%9d%ef%bc%89%e6%b0%8f%ef%bc%88%e5%b0%86%e8%bb%8d%e5%ae%b6%ef%bc%89#ieyasu|title=Genealogy|website=Reichsarchiv|date=May 6, 2010 |access-date=December 17, 2017|language=ja}}

|boxstyle_1=background-color: #fcc;

|boxstyle_2=background-color: #fb9;

|boxstyle_3=background-color: #ffc;

|boxstyle_4=background-color: #bfc;

|1= 1. Tokugawa Ieyasu, 1st Tokugawa Shōgun

|2= 2. Matsudaira Hirotada (1526–1549)

|3= 3. O-dainokata (1528–1602)

|4= 4. Matsudaira Kiyoyasu (1511–1535)

|5= 5. Haruhime

|6= 6. Mizuno Tadamasa (1493–1543)

|7= 7. Keyōin (1492–1560)

|8= 8. Matsudaira Nobutada (1490–1531)

|9= 9. Iwakura-dono Masako Mitsunaka

|10= 10. Matsudaira Masayasu (d. 1525)

|11=

|12= 12. Mizuno Kiyotada (d. 1509)

|13=

|14= 14. Aoki Izumi

|15=

}}

Ieyasu's life and accomplishments were used as a model for the Japanese statesman Lord Yoshi Toranaga, portrayed in James Clavell's historical novel Shōgun. The 1980 television miniseries adaptation of the novel, starring Toshiro Mifune as Toranaga, and the 2024 miniseries, starring Hiroyuki Sanada as Toranaga, both used Ieyasu as a key reference.{{cite web |last1=Andreeva |first1=Nellie |last2=Petski |first2=Denise |title=FX Orders 'Shōgun' Limited Series Based On James Clavell Novel – TCA |url=https://deadline.com/2018/08/fx-orders-shogun-limited-series-based-on-james-clavell-novel-tca-1202439558/ |website=Deadline Hollywood |access-date=August 3, 2018 |date=August 3, 2018 |archive-date=August 5, 2018 |archive-url=https://web.archive.org/web/20180805234041/https://deadline.com/2018/08/fx-orders-shogun-limited-series-based-on-james-clavell-novel-tca-1202439558/ |url-status=live }}{{Cite web |last=Zee |first=Michaela |date=November 2, 2023 |title='Shōgun' Trailer: Hiroyuki Sanada Headlines FX's Feudal Japan Epic, Which Brings James Clavell's Novel to Ambitious Life |url=https://variety.com/2023/tv/news/shogun-trailer-hiroyuki-sanada-fx-hulu-1235776974/ |access-date=November 3, 2023 |website=Variety |language=en-US |archive-date=November 2, 2023 |archive-url=https://web.archive.org/web/20231102150419/https://variety.com/2023/tv/news/shogun-trailer-hiroyuki-sanada-fx-hulu-1235776974/ |url-status=live }}

The NHK show {{Nihongo|1=What Will You Do, Ieyasu?|2=どうする家康|3=Dousuru Ieyasu|4=What Would You Do, Ieyasu?{{cite web|url=https://nhkworldpremium.com/en/program/425|title=Historical Drama "What Would You Do, Ieyasu?"|publisher=Japan International Broadcasting Inc.|access-date=8 April 2023|archive-url=https://web.archive.org/web/20230408110902/https://nhkworldpremium.com/en/program/425|archive-date=8 April 2023|url-status=dead}}}}{{cite web |url= https://pf.nhk-ep.co.jp/detail/84738012344|title= What will you do, Ieyasu?|access-date= December 1, 2022|work= NHK Enterprises}} is a Japanese historical drama television series depicting a semi-fictional history of Tokugawa Ieyasu which starred Jun Matsumoto as Ieyasu.{{cite web |url= https://english.kyodonews.net/news/2021/01/a37b88b88e43-japan-pop-group-arashis-matsumoto-cast-as-lead-for-2023-nhk-drama.html|title= Japan pop group Arashi's Jun Matsumoto cast as lead for 2023 NHK drama|access-date= December 1, 2022|work= Kyodo News}}{{cite web|url=https://www.nhk.or.jp/dramatopics-blog/2000/442313.html|title=2023年 大河ドラマ「どうする家康」主演は松本潤さん！|date=January 19, 2021|access-date=July 13, 2022|work=NHK|archive-date=December 20, 2022|archive-url=https://web.archive.org/web/20221220122908/http://www.nhk.or.jp/dramatopics-blog/2000/442313.html|url-status=dead}}

Tokugawa Ieyasu appears as a leader of Japan in every Civilization game except Civilization V.{{cite web|url=https://civilization.2k.com/civ-vi/leader-pass/great-commanders/|title=GREAT COMMANDERS PACK|access-date=August 27, 2024|publisher=2K|website=civilization.2k.com}}

The Age of Empires III: The Asian Dynasties expansion pack has a Japanese campaign which focuses on the unification of Japan and the establishment of the Tokugawa Shogunate with a fictional protagonist Sakuma Kichiro serving under Tokugawa Ieyasu.

In Dinosaur King, Tokugawa Ieyasu appears in episode 63 of season 2

{{Portal|Japan|History|Biography}}

• Shitennō (Tokugawa clan)
• East Asian age reckoning
• List of Tōshō-gū
• Testament of Ieyasu

{{notelist}}

{{Reflist|35em}}

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{{s-bef|before=Sengoku period}}

{{s-ttl|title=Shōgun:
Tokugawa Ieyasu|years=1603–1605}}

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{{People of the Sengoku period|state=autocollapse}}

{{Tokugawa_officials}}

{{Tokugawa dynasty (Japan)}}

{{Tokugawa chronology (Japan)}}

{{Shoguns}}

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{{DEFAULTSORT:Tokugawa, Ieyasu}}

Category:samurai

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