German submarine U - 521 German submarine " U - 521 " was a Type IXC U - boat of the Nazi German Kriegsmarine during World War II . She was built by the Deutsche Werft yard at Finkenwerder , Hamburg with yardnumber 336 . Commissioned in June 1942 , she was commanded by Kapitänleutnant Klaus Bargsten . The U - boat was assigned to the 4th U - boat Flotilla for training and the 2nd flotilla for operations . " U - 521 " was sunk on 2 July 1943 by the submarine chaser USS " PC - 565 " . The only survivor was Bargsten himself . This was the second boat under Bargsten ' s command , and the first that suffered heavy losses . The wreck of the submarine has never been found . Operational career . 1st patrol . " U - 521 " sailed from Hamburg on her first patrol on 6 October 1942 . She followed the usual course , sailing up the coast of Norway and then west , through the " Rosengarten " into the Atlantic . When she was north of Scotland , " U - 521 " was attacked by an aircraft . According to Bargsten , he was standing on the bridge when the aircraft suddenly appeared out of the clouds , flying very low . The aircraft was carrying a trailing antenna , which almost struck the boat . Bargsten thought at first that it was a new weapon . The bomb - bay doors were open , but the aircraft did not drop any bombs . " U - 521 " submerged , and , after it had gained considerable depth , several bombs were heard to explode . The first war cruise lasted over nine weeks and accounted for five merchant vessels and a corvette . Two ships were sunk from an eastbound convoy and two more from one that was westbound . The fifth ship was a freighter which had been crippled by an attack from another U - boat and had dropped out of her convoy . She was guarded by a corvette . " U - 521 " approached this target at night on the surface . The first torpedo was fired at a range of about . Due to the presence of the corvette , Bargsten was somewhat cautious , and after firing , immediately turned the boat in order to be able to fire again from his stern tube while escaping . The first torpedo passed astern of the merchantmen and hit the corvette which sank rapidly . The freighter was then easily disposed - of at close range . " U - 521 " s first patrol ended on 8 December 1942 . She put in at Lorient in occupied France where she had been assigned to the 2nd U - boat Flotilla , commanded by " Korvettenkapitän " Viktor Schütze of the 1925 naval term . Schütze was greatly admired by Bargsten , he spoke of a four - hour interview that he ( Bargsten ) had had with the flotilla commander . Bargsten was given credit for having sunk 29 , 000 tons of shipping and one corvette . " U - 521 " remained in Lorient for about three weeks , taking on supplies and preparing for her next sortie . 2nd patrol . " U - 521 " sailed from Lorient on her second patrol on 7 January 1943 . Her operational area was in the vicinity of the Azores . She attacked several convoys on this patrol in the company of other U - boats . One of these attacks took place about 25 February 1943 in company with commanded by " Oberleutnant " Hans Johannsen ( " U - 569 " was sunk on 22 May 1943 ) . During the course of an attack on a Gibraltar - bound convoy , " U - 521 " sank three ships . After firing at the last of the three , Bargsten noticed another U - boat on a collision course with his boat . " U - 521 " came to a full stop , the other submarine crossed her bow about away . These maneuvers attracted the attention of American destroyers escorting the convoy , and " U - 521 " was severely depth charge d . Although about 70 depth charges were dropped , Bargsten was rather scornful of this attack . He stated that he easily eluded his enemies without making use of the S . B . T . and he criticized the destroyers for a lack of tenacity . The U - boat sustained some damage , including a slightly bent propeller shaft . In spite of the damage , " U - 521 " was able to remain at sea and succeeded in sinking another merchantman and a corvette . The freighter , a liberty ship , was hove - to and was being guarded by a corvette when she was sighted by the U - boat . It was a bright moonlit night , and the corvette was patrolling the dark side of the freighter . Bargsten , realizing that the corvette expected an attack from the dark side , approached from the moonlit side , on the surface . While drawing near to his target , Bargsten turned to his Executive Officer and said ; " " I feel like a naked man walking through the streets of a city . " " The Executive Officer fired five torpedoes . Four of them missed completely , the fifth hit the corvette just as she was coming forward of the target . A sixth torpedo was fired by the Second Watch Officer and found its mark . Bargsten attributed the Executive Officer ' s poor marksmanship to the fact that he failed to take into account the slight roll of the boat when he was making his calculations . When " U - 521 " was almost ready to return to her base , she was met by a supply U - boat from which she transferred oil and provisions . Bargsten stated that other U - boats were present , including " U - 569 " . " U - 521 " returned to Lorient on 26 March 1943 after having been at sea for 79 days . Schütze had been replaced by " Korvettenkapitän " Ernst Kals of the 1924 naval term as Commanding Officer of the 2nd U - boat Flotilla . Bargsten ' s interview with Kals was a brief one , he felt that Kals was much less understanding than Schütze . Bargsten was credited with sinking 39 , 000 tons of shipping and one corvette on this patrol . " U - 521 " entered drydock in Lorient for repairs . Bargsten was given leave and went to his home in Bremen where he remained until 28 April 1943 . While in Bremen , he witnessed a daylight bombing raid by American B - 17 Flying Fortress es . He said that about 20 of the American bombers were shot down . Bargsten arrived back in Lorient on 29 April 1943 . On 2 May , he was awarded the Knight ' s Cross of the Iron Cross . " Korvettenkapitän " Hans - Rudolf Rösing of the 1924 naval term made the presentation . Three days later , " U - 521 " sailed on her last patrol . 3rd and final patrol . " U - 521 " sailed from Lorient at about 1300 German Summer Time , on 5 May 1943 . Her operational area was designated as being off the U . S . coast in the neighborhood of Cape Hatteras . She reached this area about 30 May , and on the same day , sighted planes and two destroyers . However , the boat was not discovered . On 2 June at about 1200Q , " U - 521 " was proceeding on a course of 250° ( WSW ) at a depth of . The sound operator reported propeller noises , but a few minutes later he reported that the noises had faded out and that all was quiet . Bargsten was lying in his bunk reading a travel book , immersed in a chapter called " Middletown , U . S . A . " , as the submarine chaser gained a Q . C . ( sonar ) contact on " U - 521 " and closed in for the attack . Sinking . At about 1230Q in position , while escorting Convoy NG - 365 , the submarine chaser USS " PC - 565 " obtained her first contact on " U - 521 " . She altered course , maintained contact , and at 1239Q dropped a standard five charge pattern set for 100 feet . Meanwhile , Bargsten was peacefully reading in his bunk when the sound operator rushed in to report propeller noises directly overhead . Immediately thereafter , the depth charges exploded . Instruments were shattered , the lights went out , the motors stopped , rudder and diving planes were rendered useless , and water entered the control room through the depth and tank pressure gauge connections . Bargsten at once gave the order to dive , although he did not know the extent of the damage received . After a few seconds , the Engineer Officer reported that the boat was at . Bargsten told him that that was " nonsense " , but the Engineer insisted and called off further readings from the control room depth gauge : " 160 metres ; 170 metres " . The accuracy of the depth charges was devastating . Inside " U - 521 " , all instruments were shattered , all breakers blown and the diving planes and rudder were also disabled . Cold seawater was coming down the main hatch . Bargsten gave the order to dive for cover . After a few seconds , " Oberleutnant " Ing . Henning reported that they were sinking . She was already down to and dropping rapidly . Even though it did not make sense to Bargsten that the U - boat could plummet so quickly , he gave the order to blow all ballast . The main depth gauge must have been knocked out by the depth charges . Bargsten subsequently realised that the U - boat could not have descended to the depths called off by the Engineer Officer without becoming heavy by the bow or the stern , whereas she had kept an even keel throughout . Upon breaking the surface , Bargsten went to the bridge to make a topside estimate of the situation . " PC - 565 " was about distant when the U - boat appeared . The patrol craft fired about 55 rounds with her 20 mm gun , scoring several hits on the conning tower . The gun jammed as the ship was turning to ram her target . Another escort vessel , USS , fired one shell from her No . 1 gun and missed the U - boat by about . She ceased firing then , as " PC - 565 " was in the line of fire . When Bargsten observed the maneuvers of " PC - 565 " and saw the patrol craft bearing down on him , he realized the U - boat ' s position was hopeless and gave the order to flood and abandon ship . It was not until he saw his Engineer Officer coming through the conning tower hatchway , that Bargsten realised the former had become panicky , since the Engineer ' s station was in the control room . His last view of his boat was of water pouring down the conning tower hatch as she went under . " U - 521 " then suddenly sank , leaving Bargsten swimming in the water . All 51 crew members died , except Bargsten himself . When the U - boat disappeared , " PC - 565 " altered course to the right to pass ahead of the swirl . At 1243Q she dropped one depth charge set at about ahead of the position of the sinking . She then moved in to pick up the only survivor , and several large air slugs were observed . The patrol craft continued to search the area and at 1325Q several oil slicks were sighted . One slick was dark with globules of brown oil , but it was not iridescent . Patches of vegetable fiber and splinters of freshly broken wood were observed . At 1338Q , " PC - 565 " picked up a large piece of human flesh . The search was abandoned at 1430Q . At 0045 on 3 June , USS conducted a box search in the vicinity of the sinking . Results were negative . At daylight , an oil slick was seen , originating at the approximate position of the sinking and extending for about . Its width varied from . Samples of oil were taken and after analysis , proved to be lubricating oil . Operating on the theory that the U - boat was not sunk but was proceeding submerged and bleeding oil , " Chickadee " conducted a box search in the vicinity of the origin of the slick . The results were again negative . It was observed that the current was flowing in the direction of the wind . The conclusion was reached that the combined effect of wind and current caused the great length of the oil slick and that in fact , the U - boat had been sunk . NOAA provides a record of the vessel at record 992 at chart 12200 , indicating that the vessel is within 3 – 5 miles of the coordinates provided .