At 16.16 hours on 16 Dec, 1943, the John S. Copley (Master Arthur Dowell) was torpedoed by U-73, while joining the station #21 of convoy GUS-24 off Oran. The U-boat was sunk by the escorts shortly after the attack.

One torpedo struck the John S. Copley on the starboard side forward of the mainmast in the empty #2 hold, which flooded quickly, causing a 8° list. The explosion created a hole 18 feet long and threw oil and water in the air and all over the vessel. Four of the five landing craft on deck were also thrown in the air and fell back on deck. The engines were secured as the steering gear failed. 34 crewmen and 12 armed guards of the eight officers, 36 crewmen, 28 armed guards (the ship was armed with two 3in and eight 20mm guns) and one passenger (US Army security officer) were ordered to abandon ship in four lifeboats and stand by the ship. The skeleton crew determined that the damage was not fatal and the engines were restarted after some of the men in the boats had reboarded the vessel.
Three harbour tugs were sent out from Oran to assist the ship and the American rescue tug USS ATR-47 took her in tow. The vessel was repaired and returned to service. The 38 men (including two injured) in the boats were picked up by the American submarine chasers USS PC-546 and USS SC-977 just outside the harbour and landed at Oran.