Between 19.48 and 19.56 hours on 11 Nov 1942, U-173 fired torpedoes at the anchored ships of convoy UGF-1 in the Fedhala roads and heard three detonations. Schweichel reported only one ship damaged, because no visual observations were made due to A/S activity. In fact, the transporter USS Joseph Hewes (AP 50) was sunk and the oiler USS Winooski (AO 38) and the destroyer USS Hambleton (DD 455) were damaged.

The USS Joseph Hewes (AP 50) (Capt Robert M. Smith) was part of the Task Group 34.9 (Center Attack Group, Western Naval Task Force) in Operation Torch, the invasion of North Africa. The transport had arrived at 07.05 hours on 8 November off Fedala and landed 80 officers and 1074 rankings of the reinforced 3rd US Army Division, vehicles and supplies. At the time of the attack, she had been completely unloaded and had taken 30 wounded soldiers on board.
At 19.50 hours on 11 November, the transport was struck by one torpedo in the #2 hold and settled by the bow as the ship began filling rapidly with water. The master endeavored to pick up anchor or slip chain but, as the entire forecastle was under water, this was not possible. An attempt was made to beach the ship by backing engines but her propeller was out of the water, so the order was given to abandon ship. At 20.32 hours, the USS Joseph Hewes (AP 50) sank, taking Captain Smith and over 100 seamen and soldiers with her. By his coolness, calmness, and his devotion to duty in placing the safety of the crew and ship before his own, he instilled confidence in every officer and member of the crew.