Battle of The St. Lawrence

The Battle of the St. Lawrence involved a number of submarine and anti-submarine actions throughout the lower St. Lawrence River and the entire Gulf of Saint Lawrence, Strait of Belle Isle and Cabot Strait from May–October 1942, September 1943, and again in October–November 1944. During this time, German U-boats sank a number of merchant ships and three Canadian warships.

In the inter-war years, poor economic conditions and a sense of security, engendered by the proximity of the United States, had resulted in the Royal Canadian Navy (RCN) being reduced to six destroyers and some minesweepers, and incapable of defence of its coastal waters. At the start of the war, Canadian naval deployment gave priority to the North Atlantic convoy routes. However, by war's end, the RCN was the third largest allied naval power in the world, with 100,000 men and women and 400 vessels.