The British and Americans planned a combined operation to land a large force in Morocco in north Africa. The Royal Canadian Navy (RCN) supplied LCM (landing craft mechanized: armoured landing craft that could carry vehicles, light tanks, and troops) vessels and 17 corvettes for escort and support duty. As a result, the RCN experienced a critical shortage of escorts for North Atlantic convoys. On 4 October, Convoy SC-107, a group of 42 slow Canadian and American merchant vessels, left Halifax bound for Liverpool, England. The RCN escort consisted of the destroyer HMCS Restigouche and three corvettes.
A German U-boat (submarine) sighted the convoy off the southern coast of Newfoundland. After the U-boat had radioed the position of Convoy SC-107, a fleet of 17 German submarines deployed along the route of the slow-moving convoy. Over a period of five days, the German U-boats subjected the convoy to relentless attacks, sinking 15 merchant ships. Among the vessels destroyed was an ammunition ship that exploded so violently that a nearby German submarine, U-132, sustained heavy damage and sank.