German submarine U-31 (1936)

German submarine U-31 was a Type VIIA U-boat of the Nazi German Kriegsmarine during World War II. She was laid down on 1 March 1936 as Werk 912, launched on 25 September and commissioned on 28 December 1936.

Service history
During her career U-31 was involved in seven war patrols, and attacked the first convoy of World War II, OB-4 on 16 September 1939, sinking the British steamer SS Aviemore.

In U-31's entire career she sank 11 ships, totalling, and one auxiliary warship of. A mine laid by U-31 damaged the British battleship HMS Nelson (28) of 33,950 tons.

On 11 March 1940 U-31 was sunk in the Jade estuary by bombs from a British Blenheim bomber with the loss of all 58 crew. The U-boat was raised later that month, repaired and returned to service in July.

U-31 was sunk again on 2 November 1940, north-west of Ireland, by depth charges from the British destroyer HMS Antelope (H36), which picked up 44 survivors (or 43, sources vary), from the crew of 46.