German submarine U - 754 German submarine " U - 754 " was a Type VIIC U - boat deployed by the German Kriegsmarine during the Second World War against allied shipping in the Atlantic Ocean . She was a successful if short - lived boat , sinking 13 ships during her career . She was most notorious for her final attack , in which she shelled and sank the small fishing vessel MV " Ebb " , and killed a number of its crew with machine - gun fire as they attempted to launch a life raft . She was sunk with all hands by a Royal Canadian Air Force bomber three days later on 31 July 1942 . The " U - 754 " was built in the Kriegsmarinewerft at the main fleet base of Wilhelmshaven in Northern Germany on the North Sea . She was completed on 28 August 1941 , and given to the experienced Kapitänleutnant Johannes Ostermann to command . Following her work - up period in which the boat was tested and the crew trained , she was despatched on her first patrol . War patrols . 1st patrol . " U - 754 " departed Kiel on her first patrol on 30 December 1941 , and her operating area was primarily in the mouth of the St Lawrence River , operating against convoys entering or leaving the waterway , or destined for the many ports at the river ' s mouth , such as Halifax , Nova Scotia or St . John ' s , Newfoundland . During this patrol , she sank four freighters . The submarine narrowly escaped a bombing attack by a Royal Canadian Air Force Bolingbroke bomber on 23 March which inflicted minor damage . The submarine returned to Brest in France on 2 February to resupply and rearm . 2nd patrol . The second patrol left from Brest on 9 March 1942 , and after a brief sweep in her previous area of operations , she swung south to take advantage of the Second happy time then occurring off the United States ' s Eastern Seaboard . During this patrol she sank seven more ships ; three of them in one attack on a small coastal convoy , in which she hit several small barges and coastal cargo ships . She sank the tanker by torpedo on 23 March . " U - 754 " returned to Brest on 25 April 1942 . 3rd patrol . Her final patrol was her least successful , in terms of ships sunk , although the tonnage was higher , as she sunk the 12 , 435 - ton SS " Waiwera " in the mid - Atlantic on 29 June , ten days after leaving Brest . Attack on F / V Ebb . It was nearly a month later , on 28 July , that " U - 754 " scored her final victim , when she controversially shelled the fishing vessel " Ebb " near Cape Sable Island , Nova Scotia . The " Ebb " was a motor fishing trawler operating out of Boston for the General Sea Foods Company . The crew of the small 260 - ton vessel felt it was unlikely that they would be troubled by the war , as she was far too small for an effective torpedo shot , and too insignificant to justify the risk of a surface attack by gunfire . On 28 July 1942 , however , while fishing off Cape Sable her crew were shocked to see " U - 754 " emerge from the water . The submarine immediately opened fire without warning on " Ebb " with her anti - aircraft guns . The ship stopped and made signals that they had surrendered , but the gunfire continued , one gun sweeping through the crowd of crew members attempting to launch the ship ' s life raft . Five of the seventeen crew were killed and seven more seriously wounded , before the " Ebb " sank after taking over fifty hits . The survivors were discovered and rescued by the W class destroyer fourteen hours later . Had " U - 754 ' s " crew survived the war , it is possible that they would have been charged with war crimes as were the officers of who also fired on sailors who had abandoned their ship . Similar incidents of gun attacks aimed at crews occurred on the and . RCAF attack and sinking . Radio transmissions from " U - 754 " betrayed a pattern to Royal Canadian Navy intelligence , information which was used by Norville Everett Small the commander of RCAF 113 Squadron to deploy patrols from RCAF Station Yarmouth targeting the suspected position of " U - 754 " . On 31 July , a Hudson bomber piloted by Squadron Leader Small himself caught " U - 754 " on the surface south of Yarmouth not far from the scene of the " Ebb " sinking . The submarine was precisely straddled by a cluster of depth charges as it began to dive . The conning tower of the wounded submarine briefly surfaced to be strafed by the Hudson ' s machine guns before submerging for the last time . A trail of large air bubbles was followed by a massive underwater explosion as " U - 754 " went to the bottom with all 43 hands . It marked the first submarine kill of the RCAF ' s Eastern Air Command .