German submarine U - 415 German submarine " U - 415 " was a Type VIIC U - boat built for the " Kriegsmarine " for service during World War II . She was laid down on 12 July 1941 at the " Danziger Werft " in Danzig ( now Gdansk ) , as ' werk ' 116 . She was launched on 9 May 1942 and commissioned on 5 August . She completed seven patrols before being sunk by a mine on 14 July 1944 . Her first Commanding Officer was " Kapitänleutnant " Kurt Neide . He took her on five patrols between March 1943 and March 1944 . Her second and last CO was " Oberleutnant " Herbert Werner , who completed two patrols in her between April and July 1944 . Beginning . These patrols were preceded by a trip to Bergen in Norway in February and March , 1943 . First , second and third patrols . Her first patrol saw her leave Bergen on 7 March 1943 and took her to an area south of Greenland where she torpedoed , but did not sink , the British ship " Wanstead " on 21 April . The ship was sailing in ballast , ( the " coup de grace " was administered by ) . " U - 415 " then sailed for Brest in France , but was attacked west of the Bay of Biscay on 1 May ; first by a Handley Page Halifax of No . 502 Squadron RAF and later that the same day by a Whitley from 612 squadron , also RAF . She was damaged , but managed to reach her destination on 5 May . Her second sortie began in the company of and . The small flotilla was detected by a RAF Whitley on 14 June 1943 off the northwest coast of Spain , but the aircraft only attacked when the trio dived . No damage was sustained . The boat was also attacked by a corvette off the coast of Trinidad on 24 July , while hunting a convoy Her third patrol , beginning on 27 October 1943 , was marred by the attack of a Vickers Wellington equipped with a Leigh Light off Cape Ortegal in the Bay of Biscay on 30 October . The aircraft dropped four depth charge s which caused enough damage to ensure that the submarine was compelled to return to base . The Wellington was shot down during the action , all six crew members were killed . Fourth and fifth patrols . Her fourth operational effort was rewarded by the sinking of the " H " - class destroyer . " U - 415 " encountered the warship on Christmas Eve ( 24 December ) 1943 northeast of the Azores . " Hurricane " was crippled by a GNAT acoustic torpedo and had to be finished off the following day . On her return journey " U - 415 " was attacked by a Halifax of 58 squadron , on 5 January 1944 . The aircraft dropped six depth charges on the U - boat which returned fire before diving . The submarine reached her home port the following day . " U - 415 " s fifth patrol came to a sudden halt in mid - Atlantic when she was attacked on 16 March 1944 by aircraft and ships escorting convoy CU 17 . The boat was severely damaged and returned to Brest on 31 March . Sixth and seventh patrols . " U - 415 " s sixth patrol was even shorter . By now under the command of " Oberleutnant " Herbert Werner , the boat moved into the relatively shallow water of the Western Approaches as ( according to Werner ' s flotilla commander ) : " we have temporarily suspended our long patrols into the Atlantic in favor of shorter operations into areas where the convoy routes converge " . She had left Brest on 11 April 1944 and endured a series of aerial assaults ; the non - schnorkel equipped boat establishing a grim routine of diving and surfacing ( to charge batteries ) until the third day of her patrol when she began stalking a convoy . Having manœuvred into position , she fired a total of five torpedoes and scored three hits . The response was swift ; over the next 37 hours a succession of some 300 depth charges were dropped , all to no avail . An hour after the last escort withdrew , " U - 415 " surfaced . Not long afterwards , she dived again , to the relatively shallow depth of where among the mass of radio messages she received was one ordering her to return to base . " U - 415 " s next outing was not really a patrol at all . Werner had been recalled to help counter the long expected Allied invasion of France . The boat had been put in dry dock for an overhaul while the skipper tried to arrange the fitting of a schnorkel ( he was unsuccessful ) . " U - 415 " received two messages from BdU ( U - boat headquarters ) ; the first , which instructed all boats to : ATTACK AND SINK [ the ] INVASION FLEET WITH THE FINAL OBJECTIVE OF DESTROYING ENEMY SHIPS BY RAMMING . It was received before the landings . < br > The second was just as dramatic for " U - 415 " and the other non - schnorkel equipped boats : . . . PROCEED ON SURFACE AT TOP SPEED TO [ southwestern ] ENGLISH COAST . . . ATTACK AND DESTROY ALLIED SHIPPING . It was received after the invasion . The submarine was then part of an eight - boat procession out of Brest harbour . Almost immediately they came under attack from the air . " U - 413 " and were crippled ; nor did " U - 415 " escape damage , her starboard engine was knocked off its mounting and a fuel tank was ruptured , although she shot a Liberator down . The damage was serious enough to warrant an immediate return to Brest . But it was not that easy . " U - 415 " , which had cautiously dived , was blind , both periscopes were out of action ; she ran into rocks off the Brittany coast . Extricating herself with difficulty , she surfaced and headed for home . An aircraft sighting , closer than most , forced the vessel to dive once more . The boat , with all power lost , hit the bottom at . Werner decided to surface once more , in the hope of meeting a friendly escort . In an effort to free the submarine from the ocean floor , he ordered all men forward , then aft . After several attempts and all tanks being blown with their diminishing supply of compressed air , " U - 415 " reluctantly came free and broke the surface . She then limped into port . " U - 415 " ' s Chief Engineer had a list of nearly 500 repairs which was reduced to 55 due to the lack of spares and time . It was also decided to cannibalize " U - 256 " for the benefit of " U - 413 " and " U - 415 " , leaving just two U - boats in Brest . " U - 415 " s loss was preceded by a sally into the waters west of her home port . No ships of any description were sighted , but the air threat was ever present . Following an exchange of radio messages , " U - 415 " was directed to return to Brest where she was given just three days to prepare for her next patrol . Werner , who had " not slept for ten days " , was woken on 14 July by a steward ; as he was moving from his accommodation to the harbour and preparing to reprimand his Executive Officer for moving " U - 415 " without his authorization , a tremendous explosion rocked the area . The boat had activated a mine and sank soon afterwards . Two men died and 14 were wounded . Aftermath . Werner and some of the crew members from " U - 415 " were moved to " U - 953 " . Werner survived the war and wrote the best - selling " Iron Coffins " .