Battle of Bonari Pass

{{Short description|1868 battle of the Boshin War}}{{More citations needed|date=May 2024}}{{Infobox military conflict

| conflict = Battle of Bonari Pass

| partof = Boshin War

| image = Bonari pass.jpg

| caption =

| date = {{Start date|1868|10|06}}

| place = Inawashiro, Fukushima

| coordinates = {{WikidataCoord|display=it}}

| map_type = Japan

| map_relief = yes

| map_size =

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| map_caption =

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| territory =

| casus =

| result = Imperial victory

| combatant1 = Imperial Japanese Army

| combatant2 = Bakufu Army

| commander1 = Itagaki Taisuke
Ijichi Masaharu
Murata Tsuneyoshi

| commander2 = Ōtori Keisuke
Hijikata Toshizō

| strength1 = 3,000

| strength2 = 800

| casualties1 =

| casualties2 =

}}

{{Campaignbox Boshin War}}

The Battle of Bonari Pass (Japanese: {{lang|ja|母成峠の戦い}}) was part of the Boshin War, and occurred on the 6 October 1868 (Gregorian Calendar), or the 21st day of the Eighth Month, Keiō-4 year (Japanese calendar). The Bonari pass was a strategic access at the limit of the fief of Aizu.

The battle was between a mixed force of 800 troops – including former shogunate soldiers (Denshūtai and Shinsengumi) led by Ōtori Keisuke and Hijikata Toshizō, Aizu forces, and soldiers of various northern domains — against a much larger number of troops favourable to the Imperial government.

Itagaki Taisuke led his troops, by some estimates numbering as many as 3,000, in a rapid strike against forces defending Aizuwakamatsu Castle.{{Cite book |last=Turnbull |first=Stephen R. |title=Samurai: The world of the warrior |date=2003 |publisher=Osprey |isbn=1 84176 740 9 |location=Oxford |pages=177}} Heading southwest from Nihonmatsu, Itagaki then took a route across Bonari Pass northwards to cross into Aizu.

Outnumbered, the shogunal troops had to retreat to the North to Sendai, where the fleet of Enomoto Takeaki was ready to evacuate them to Hokkaidō. This left Aizu exposed, and facilitated the imperial advance.

Three days later, the Imperial troops reached the castle of Wakamatsu and laid siege to it, in the key action of the Battle of Aizu.