German submarine U-31 (1936)

As one of the first ten German Type VII submarines later designated as Type VIIA submarines, U-31 had a displacement of {{convert|626|t|LT}} when at the surface and {{convert|745|t|LT}} while submerged.{{sfn|Gröner|Jung|Maass|1991|pp=43–44}} She had a total length of {{convert|64.51|m|ftin|abbr=on}}, a pressure hull length of {{convert|45.50|m|ftin|abbr=on}}, a beam of {{convert|5.85|m|ftin|abbr=on}}, a height of {{convert|9.50|m|ftin|abbr=on}}, and a draught of {{convert|4.37|m|ftin|abbr=on}}. The submarine was powered by two MAN M 6 V 40/46 four-stroke, six-cylinder diesel engines producing a total of {{convert|2100 to 2310|PS|kW shp|-1}} for use while surfaced, two BBC GG UB 720/8 double-acting electric motors producing a total of {{convert|750|PS|kW shp}} for use while submerged. She had two shafts and two {{convert|1.23|m|ft|abbr=on|0}} propellers. The boat was capable of operating at depths of up to {{convert|230|m}}.{{sfn|Gröner|Jung|Maass|1991|pp=43–44}}

The submarine had a maximum surface speed of {{convert|17|kn}} and a maximum submerged speed of {{convert|8|kn}}.{{sfn|Gröner|Jung|Maass|1991|pp=43–44}} When submerged, the boat could operate for {{convert|73|-|94|nmi}} at {{convert|4|kn}}; when surfaced, she could travel {{convert|6200|nmi}} at {{convert|10|kn}}. U-31 was fitted with five {{convert|53.3|cm|in|0|abbr=on}} torpedo tubes (four fitted at the bow and one at the stern), eleven torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and an anti-aircraft gun. The boat had a complement of between forty-four and sixty.{{sfn|Gröner|Jung|Maass|1991|pp=43–44}}

During her career U-31 was involved in seven war patrols.

U-31 was one of the few ocean-going submarines deployed to the Baltic Sea instead of the Atlantic Ocean on the eve of World War II. Departing Memel under the command of Johannes Habekost on 27 August, this uneventful trip was concluded quickly with the rapid destruction of the Polish Navy and the boat put in at Wilhelmshaven on 2 September.{{Cite web |url=https://uboat.net/boats/patrols/patrol_220.html |title=Patrol info for U-31 |last=Helgason |first=Guðmundur |website=German U-boats of WWII - uboat.net |access-date=2017-11-06}}

After her quick return to Germany, U-31 became one of three Type VII reserve boats, going to sea again when Karl Dönitz ordered a redeployment of the U-boat force on 8 September. Ordered along with {{GS|U-35|1936|2}} to save time by directly proceeding to the Atlantic via the English Channel,Blair, page 84 she attacked the first convoy of World War II, OB 4 on 16 September 1939, sinking the British steamer SS Aviemore.{{Cite web |url=http://uboat.net/allies/merchants/ships/27.html |title=Aviemore (Steam merchant) |last=Helgason |first=Guðmundur |website=German U-boats of WWII - uboat.net |access-date=2009-12-19}} Habekost had found the convoy the day before and per orders reported the convoy's location, course and speed to Dönitz. Excited by this first reliable convoy report, he ordered all available boats to converge and attack the convoy. U-31 maneuvered into attack position and in the nighttime hours made an attack. Thinking he had sunk two ships, Habekost had however suffered torpedo failure, and thus only the 4,060 GRT Aviemore was actually sunk out of the convoy by U-31. U-31 would later sink the slightly larger Hazelside, of 4,646 GRT, on 24 September before concluding the patrol and returning to Wilhelmshaven on 2 October 1939.{{Cite web |url=https://uboat.net/boats/patrols/patrol_221.html |title=Patrol info for U-31 |last=Helgason |first=Guðmundur |website=German U-boats of WWII - uboat.net |access-date=2017-11-06}}

On 11 March 1940 U-31 was sunk in the Schillig Roads near buoy 12 ({{coord|53|37|N|08|10|E}}) by four bombs from a Bristol Blenheim, O of No. 82 Squadron RAF, with the loss of 58 lives. The U-boat had been on trials and carried eleven workers from the shipyard and two assistants to the flotilla engineer in addition to her regular complement.{{sfn|Busch|Röll|1999|p=17}}

The U-boat was raised later that month, repaired and returned to service on 30 July 1940 with Kptlt. Prellberg in command.{{sfn|Kemp|1999|p=64}}{{Cite web |url=http://www.wlb-stuttgart.de/seekrieg/40-03.htm |title=Seekrieg 1940, Märtz |last1=Rohwer |first1=Jürgen |author-link=Jürgen Rohwer |last2=Gerhard Hümmelchen |website=Württembergische Landesbibliothek Stuttgart |language=de |access-date=6 March 2015}}

U-31 was sunk again on 2 November 1940, north-west of Ireland, by depth charges from the British destroyer {{HMS|Antelope|H36|6}}, which picked up 44 survivors (or 43, sources vary), from the crew of 46.{{sfn|Kemp|1999|p=67}}

In U-31{{'}}s entire career she sank eleven merchant ships, totalling {{GRT|27,751|disp=long}}, and two auxiliary warships of {{GRT|160}}. A mine laid by U-31 damaged the British battleship {{HMS|Nelson|28|6}} of 33,950 tons.

{{Reflist|group=Note}}

{{reflist}}

{{Refbegin}}

• {{Cite book |last1=Busch |first1=Rainer |title=German U-boat commanders of World War II: a biographical dictionary |last2=Röll |first2=Hans-Joachim |publisher=Greenhill Books, Naval Institute Press |year=1999 |isbn=1-55750-186-6 |location=London, Annapolis, Md |translator-last=Brooks |translator-first=Geoffrey |ref=none}}
• {{cite book |last1=Busch |first1=Rainer |last2=Röll |first2=Hans-Joachim |title=Der U-Boot-Krieg, 1939-1945: Deutsche U-Boot-Verluste von September 1939 bis Mai 1945|trans-title=German U-boat losses from September 1939 to May 1945 |date=1999|volume=IV |publisher=Mittler|location=Hamburg, Berlin, Bonn |isbn=3-8132-0514-2 |url=https://books.google.com/books?id=vXKwAAAAIAAJ |language=de}}
• {{Cite book |last1=Gröner |first1=Erich |title=U-boats and Mine Warfare Vessels |last2=Jung |first2=Dieter |last3=Maass |first3=Martin |series=German Warships 1815–1945 |publisher=Conway Maritime Press |year=1991 |isbn=0-85177-593-4 |volume=2 |location=London |translator-last=Thomas |translator-first=Keith |translator-last2=Magowan |translator-first2=Rachel}}
• {{Cite book |last=Kemp |first=Paul |title=U-Boats Destroyed - German Submarine Losses in the World Wars |publisher=Arms & Armour |year=1999 |isbn=1-85409-515-3 |location=London }}

{{Refend}}

• {{Cite web |url=http://uboat.net/boats/u31.htm |title=The Type VIIA boat U-31 |last=Helgason |first=Guðmundur |website=German U-boats of WWII - uboat.net |access-date=8 December 2014}}
• {{Cite web |url=http://www.u-boot-archiv.de/dieboote/u0031.html |title=U 31 |last=Hofmann |first=Markus |website=Deutsche U-Boote 1935-1945 - u-boot-archiv.de |language=de |access-date=7 December 2014}}

{{German Type VII submarines}}

{{March 1940 shipwrecks}}

{{November 1940 shipwrecks}}

{{use dmy dates|date=December 2014}}

{{DEFAULTSORT:U0031}}

Category:1936 ships

Category:German Type VIIA submarines

Category:Military units and formations of Nazi Germany in the Spanish Civil War

Category:Ships built in Bremen (state)

Category:U-boats commissioned in 1936

Category:U-boats sunk in 1940

Category:U-boats sunk by British aircraft

Category:U-boats sunk by depth charges

Category:U-boats sunk by British warships

Category:World War II shipwrecks in the Atlantic Ocean

Category:World War II submarines of Germany

Category:Maritime incidents in March 1940

Category:Maritime incidents in November 1940