By January of 1943, the Allies were advancing on the German-Italian forces in north Africa from both the east and west. In the east, the British 8th Army pushed the German army back. In the west, the U.S. II Corps and British 1st Army moved toward Tunisia. A steady stream of Allied convoys supplied all three forces, and 17 corvettes of the Royal Canadian Navy (RCN) served vital escort duties.
In response to the Allied offensive in north Africa, the German High Command ordered Admiral Karl Dönitz to increase the number of U-boats (submarines) in the Mediterranean. The U-boats bolstered the Italian submarine force deployed along the main Allied convoy routes. As a result, the RCN corvettes were in constant action during the early months of 1943.
The HMCS Ville de Québec, commanded by Lieutenant-Commander A.R.E. Coleman, rammed and sunk a U-boat only 10 minutes after making ASDIC (a type of sonar that used sound to locate submerged submarines) contact on 15 January 1943. The HMCS Regina executed an accurate depth charge attack on an Italian submarine. Heavily damaged, the Italian submarine surfaced, and the Reginaused its deck guns to finish it off.
Nonetheless, the operations in the Mediterranean took their toll on the RCN force: the HMCS Louisburg sank in four minutes after a German torpedo struck it amidships, and a German mine claimed the HMCS Weyburn in the Straits of Gibraltar.