The Royal Canadian Navy (RCN) had few operational vessels available for escort duty in the North Atlantic. In the spring of 1940, the Royal Navy (RN) had transferred 10 corvettes to the RCN, but the Canadian forces still did not have enough escort vessels to give adequate protection to transatlantic convoys.
Shipyards in Montreal and Quebec were refitted for wartime production, and, on 4 June 1940, construction began on the first Canadian-built corvette, the HMCS Shawinigan. By the end of 1940, Canadian shipyards had produced 20 corvettes, and the rate of production would increase substantially during the following years. By the end of 1944, the RCN had 123 corvettes in service.