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 , by one of her own homing torpedos or ( more probably ) by depth charges from the British destroyer and the frigate . Service history . 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 torpedo es . However , an attack by the British destroyer and frigate on 17 January took place two days and about 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 .