In the morning on 11 March 1943, HMS Harvester (H 19) (Cdr A.A. Tait, DSO, RN), flagship of the Escort Group B3, escorting convoy HX-228, picked up 51 survivors from the William C. Gorgas, which had been sunk by U-757 (Deetz). The destroyer then returned to convoy and sighted U-444 (Langfeld). The U-boat dived, but was forced to the surface by the following depth-charge attack and rammed by the destroyer at full speed. The destroyer was locked into the U-boat with a propeller shaft and both ships were unable to manoeuvre for a while. U-444 was able to creep away but was shortly afterwards sighted by FFL Aconit (K 58), unable to dive, the U-boat was rammed for the second time and sunk.

The badly damaged HMS Harvester (H 19) managed to get one engine running and tried to catch up with convoy, but around noon her machinery broke down again. In this helpless situation she was hit by one torpedo from U-432 and a few minutes later by a second and sank almost immediately. The commander, seven officers, 136 ratings and 39 survivors were lost. At this moment, FFL Aconit (K 58) returned to the scene and with depth charges, gunfire and ramming sank U-432. During the day, the corvette picked up four survivors from U-444, 20 survivors from U-432 and 60 survivors from the destroyer, including twelve survivors from William C. Gorgas.