German submarine U - 256 German submarine " U - 256 was a Type VIIC U - boat of the Nazi German " Kriegsmarine " during World War II , she also served for a short time as an anti - aircraft submarine under the designation U - flak 2 " . During her career , " U - 256 " completed five wartime patrols and sank one warship of 1 , 300 tons . The submarine was laid down on 15 February 1941 at the Bremer Vulkan yard at Bremen - Vegesack as ' werk ' 21 . She was launched on 28 October and commissioned on 18 December under the command of " Oberleutnant zur See " Odo Loewe . " U - 256 " was assigned to the 8th U - Boat Flotilla for training , then transferred to the 9th U - boat Flotilla for operational service . Service history . 1st patrol . " U - 256 " s first patrol began on 28 July 1942 during her transfer from Kiel , Germany to the " 9 . Unterseebootsflottille " at Brest in occupied France . During the patrol , " U - 256 " unsuccessfully pursued Convoy SC 94 , and early on 25 August was detected by the radar of the Norwegian Flower class corvette astern of convoy ON 122 . The U - boat crash - dived when illuminated by star shell s , the corvette attacked with depth charge s . The boat eventually made her escape when the corvette was obliged to return to convoy protection duties , but the submarine was damaged enough to have to abort the patrol . On the return journey , on the morning of 2 September , the U - boat was attacked by a British Whitley bomber of No . 77 Squadron RAF in the Bay of Biscay . The aircraft strafed and dropped several bombs , but the U - boat ' s flak hit the aircraft and it crashed into the sea . " U - 256 " limped into Lorient the next day , due to the extensive damage from the two attacks , she was withdrawn from service in November 1942 . 2nd patrol . During an overhaul which included extensive repairs , " U - 256 " was converted to a " Flakboot " ( Flak boat ) in May 1943 . One of just four U - boats so modified , she was given an increased complement of anti - aircraft guns , to give her and other German submarines a better chance of fighting off enemy aircraft . " U - 256 " was re - commissioned as " U - flak 2 " on 16 August 1943 . The boat ' s second wartime patrol started on 4 October under the command of " Oblt . " Wilhelm Brauel ; her mission was to rendezvous with and protect , a " Milchkuh " ( ' Milk cow ' or re - supply U - boat ) . Such submarines could re - supply multiple U - boats at sea , and were consequently the prime target of Allied aircraft trying to disrupt U - boat activities . On 8 October , the outbound boat was attacked by a Leigh light - equipped British Wellington bomber of No . 612 Squadron RAF in the Bay of Biscay . " U - 256 " was not damaged by the six depth charges that straddled her , and escaped by crash - diving . " U - 256 " s return fire had hit the starboard elevator and rear turret of the aircraft , but it returned safely to base . " U - flak 2 " was caught on the surface by the American destroyer USS " Borie " on 31 October . The U - boat escaped , but with minor depth charge damage . On 16 November the inbound boat encountered a Halifax Mk . II aircraft of No . 502 Squadron RAF in the Bay of Biscay . The aircraft was damaged by flak and turned away . When the Halifax returned to the area , the U - boat had already escaped by crash - diving . " U - flak 2 " returned to her base at Brest on 17 November . The Flak conversion was not considered a success , " U - flak 2 " was converted back to her original configuration in the winter of 1943 / 44 and renamed " U - 256 " . 3rd patrol . " U - 256 " s third patrol started on 25 January 1944 . She steamed west and southwest of Ireland and on 20 February damaged the anti - submarine sloop , HMS " Woodpecker " which later sank while under tow . On 19 March , inbound in the Bay of Biscay , the U - boat was strafed by a Leigh light - equipped British Liberator of 224 Squadron . The Germans observed hits from their 20 mm and 37 mm AA guns , before the aircraft dropped six depth charges , and then crashed into the sea 500 meters away . The boat was not damaged in the attack , and returned to Brest on the 22nd . 4th patrol . " U - 256 " sailed from Brest on 6 June 1944 " ( D - Day ) " , but was seriously damaged when attacked by another Liberator , also of 224 Squadron the next day , and returned to Brest on the 8th . 5th patrol . On 4 September 1944 , under the command of " Korvettenkapitän " Heinrich Lehmann - Willenbrock , " U - 256 " became the last U - boat to leave Brest before the port was captured by the Allies . The transit from Brest to Bergen in Norway , would be " U - 256 " s last patrol . She reached her destination on 17 October , and was decommissioned there on 23 October .