German submarine U-377

German submarine U-377 was a Type VIIC U-boat of the Nazi German Kriegsmarine during World War II. The submarine was laid down on 8 April 1940 at the Howaldtswerke yard in Kiel, launched on 15 August 1941, and commissioned on 2 October 1941 under the command of Kapitänleutnant Otto Köhler.

U-377 was attached to the 6th U-boat Flotilla, and was ready for front-line service from 1 February 1942. She served with the 11th U-boat Flotilla based in Norway from July 1942, and was transferred to the 9th U-boat Flotilla based in France on 1 March 1943. She sailed on 11 war patrols between February 1942 and January 1944, but sank no ships, before she was sunk with the loss of all hands on 17 January 1944 south-west of Ireland, in position 49.65°N, -20.16667°W, by one of her own homing torpedos or (more probably) by depth charges from the British destroyer HMS Wanderer (D74) and the frigate HMS Glenarm (K258).

Norway
U-377 sailed from Kiel on 14 February 1942 and patrolled along the coast of Norway before arriving at Narvik on 28 February. This was her home port for the rest of the year, she sailed on a series of six patrols in the Barents Sea, without success.

On 30 January 1943 U-377 left Bergen and sailed out into the Atlantic, patrolling south of Greenland, before arriving at Brest in France on 18 March, having been transferred to the 9th U-boat Flotilla.

France
U-377 sailed from Brest on 15 April, out into the mid-Atlantic, and patrolled for 54 days, before returning to base on 7 June.

On 2 August 1943 her commander, Otto Köhler, left the boat and was replaced by Oberleutnant zur See Gerhard Kluth. Kluth's first patrol was quite eventful, as her first two attempts were cut short; U-377 sailed from Brest on 26 August 1943, but returned on the 30th; she sailed again on 6 September 1943, returning the next day. Finally she set out again on 9 September, joining other U-boats in mid-Atlantic. On 22 September, the U-boat was attacked by a B-24 Liberator, wounding the commander. The U-boat returned to port under the command of the I WO. Leutnant Ernst-August Gerke.

Loss
U-377 departed from Brest on 15 December 1943, with Kluth back in command, sailing out into mid-Atlantic. She made her last radio report on 15 January 1944, claiming to have attacked an unidentified search group with homing torpedoes. The BdU ("U-boat Command") expected the U-boat to head back to France on or about 29 January, so when she had failed to arrive by 10 February, she was listed as missing from 4 February 1944. After the war the Allied Assessment Committee were unable to attribute the loss of U-377 to any known anti-submarine attack, and the U-boat was officially recorded as "lost to unknown cause". The Kriegsmarine had received at least two partially corrupted unsigned coded emergency messages around the time of the U-boat's disappearance, leading to a theory that U-377 had been sunk by one of its own Zaunkoenig T-5 acoustic torpedoes. However, an attack by the British destroyer HMS Wanderer and frigate HMS Glenarm on 17 January took place two days and about 220 nmi from  U-377's last known position, where she would have been, had she been on course and sailing at the most economical speed, as ordered, making it more probable that this was the U-boat's fate.