At 18.30 hours on 4 July 1942 the William Hooper (Master Edward Lester Graves), in station #15 of convoy PQ-17, was hit on the starboard side in the engine room by one of two torpedoes from a German He111 aircraft (Hptm Bernd Eicke) of I./KG 26, which passed over the ship abaft the starboard beam. The armed guards claimed hits on another aircraft from a distance of 4000 yards and set its port engine on fire. The explosion blew engine parts and debris through the stack and the skylight, killed one officer and two crewmen on watch below and set fire in the settling tank. Seven men of the complement of eight officers, 34 crewmen and 16 armed guards (the ship was armed with one 4in, one 3in, four .50cal and two .30cal guns) panicked and jumped overboard immediately, followed by the remaining crew in three lifeboats and two rafts. 44 survivors were picked up after 40 minutes by the British rescue ship Rathlin and eleven by the Zamalek, first taken to Russia, then Scotland and later repatriated to Boston aboard the British liner Queen Mary.

The badly damaged William Hooper was shelled within one hour by a British escort vessel in an attempt to scuttle her, but the ship remained afloat and was located by U-334 later that day. At 22.59 hours, the U-boat fired a first coup de grâce which was a dud and a second at 23.03 hours that missed. The wreck was then shelled and sunk by gunfire.