German submarine U - 172 German submarine " U - 172 " was a Type IXC U - boat of the German " Kriegsmarine " during World War II . She was first assigned to the 4th U - boat Flotilla for training and on 1 May 1942 was reassigned to the 10th flotilla , an operational long - range organization . Career . " U - 172 " was laid down at the AG Weser yard in Bremen as ' werk ' 1012 . She was launched on 31 July 1941 and commissioned on 5 November under the command of " Kapitänleutnant " Carl Emmermann . She conducted six patrols , sinking 26 ships totalling ( ) . She was sunk by American aircraft and warships in December 1943 , west of the Canary Islands . 1st patrol . " U - 172 " s first patrol commenced with her departure from Kiel on 11 Mary 1942 . Her route took her through the Kattegat and Skaggerak , through the ' gap ' between the Faroe and Shetland Islands and into the Atlantic Ocean . She arrived at Lorient in occupied France on 21 July . She would use this port as her base for the rest of her career . 2nd patrol . Having left Lorient on 11 May 1942 , the boat moved into the mid - Atlantic and sank the " Athelknight " southeast of Bermuda on the 27th . Some survivors did not reach land until 23 June , having sailed some . Moving to the eastern Caribbean Sea , she sank three more ships , the " City of Alma " , the " Delfina " and the " Sicilien " in early June . She attacked the " Lebore " on the 14th , which assumed a 45° list to starboard on being hit . The ship was struck again in the engine room followed by fire from the U - boat ' s deck gun . A third torpedo caused the ship to capsize . Twelve more deck gun rounds and a ' coup de grâce ' sent the ship to the bottom . Casualties were relatively light , the first assistant engineer was the only fatality , leaving 93 men to be rescued by US warships . Four more vessels were consigned to watery graves . One of them , the Colombian sailing ship " Resolute " , was stopped with " U - 172 " s 20mm gun and sunk with grenades . Another , the " Santa Rita " , had been abandoned by her crew , but was still afloat . A party from the U - boat boarded her and set scuttling charges . The master was found and taken prisoner . He was landed at Lorient when the submarine returned to base and was transferred , initially to Wilhelmshaven then the POW camp at Milag Nord near Bremen . 3rd patrol . " U - 172 " left Lorient for her third sortie on 19 August 1942 . It would be her longest ( 131 days ) and in terms of tonnage sunk , most successful patrol . That total was boosted with the destruction of the British troopship " Orcades " ( 23 , 456 GRT ) southwest of Capetown on 10 October . She was first struck by two torpedoes , but following a third hit , a skeleton crew , gunners and volunteers from the passengers remained on board to try and save the ship . They included a Petty Officer telegraphist who sent a second distress call after the radio operators had abandoned their position . In all , the " Orcades " was hit by six torpedoes before sinking with a broken back . < br > Forty - five men died , but there were 1 , 022 survivors . Following the sinking of the " Allington Court " on 31 October , the survivors were only spotted and picked up by the " City of Christinia " when the third officer climbed a lifeboat ' s mast and waved a shirt . The " Benlomond " was another victim sunk on 23 November . The only survivor of this attack was Poon Lim , who eked out an existence for 133 days in the South Atlantic on a Carley float , ( a type of liferaft ) . He received the British Empire Medal from King George VI for this feat . 4th patrol . The true horrors of the Battle of the Atlantic were illustrated when the U - boat sank the " City of Pretoria " in mid - Ocean about northwest of the Azores on 16 March 1943 . One of the passengers had already survived 51 days in a lifeboat from a previous sinking . This time he was not so lucky - nor were the other occupants of the ship ; there were no survivors . " U - 171 " sank three other ships ; one of them , the " Benjamin Harrison " , had been a member of the ill - fated convoy PQ - 17 . The submarine did not escape unscathed ; while attacking convoy RS - 3 on 28 March , as one of eight U - boats , she was seriously damaged but still managed to sink the " Moanda " on the 29th . She was also attacked on 7 April by two B - 24 Liberator s of 1 Squadron , USAAF south of the Azores . Despite having 12 depth charge s dropped on her , she stayed on the surface , fought it out and sustained no damage . The boat returned to Lorient on 17 April . 5th patrol . For her fifth patrol , " U - 172 " moved into the waters of the South Atlantic , departing Lorient on 29 May 1943 . Having sunk the " Vernon City " south southeast of St Paul Rocks ( between South America and Africa ) on 28 June , she headed toward the Brazilian coast , where she caused the destruction of three more ships : the " African Star " ( 12 July ) , the " Harmonic " ( 15 July ) and the " Fort Chilcotin " ( 24 July ) . The submarine was attacked by unidentified aircraft on 11 August while rescuing the crew of " U - 604 " , in the aftermath of that boat ' s scuttling . One man from " U - 172 " was killed . 6th patrol and loss . " U - 172 " left Lorient for the last time on 22 November 1943 . She was sunk on 13 December , in mid - Atlantic west of the Canary Islands by Avenger and Wildcat aircraft from the escort carrier , and the American destroyers , , and . The battle between " U - 172 " and the small armada of ships and aircraft lasted for 27 hours and as many as 200 depth charges were dropped by the destroyers . Thirteen of " U - 172 " s crew were killed ; 46 survived the sinking . Summary of raiding history . < nowiki > * < / nowiki > Sailing ship