Battle of the St. Lawrence

Part of Battle of the Atlantic

Date	May 1942 – November 1944
Location	Gulf of St. Lawrence, St. Lawrence River
Result	Canadian strategic victory

Belligerents

Canada

United Kingdom

Germany

Commanders and leaders

Percy W. Nelles

Leonard W. Murray

Karl Dönitz

Casualties and losses

23 merchant ships sunk
4 RCN ships sunk
340 killed

Some U-boats damaged and some crewmen killed, All spies captured

U-190 and U-889 surrendered at the end of the war

Canada

Some U-boats damaged and some crewmen killed, All spies captured

The Battle of the St. Lawrence involved marine and anti-submarine actions throughout the lower St. Lawrence River and the entire Gulf of Saint Lawrence, Strait of Belle Isle, Anticosti Island and Cabot Strait from May–October 1942, September 1943, and again in October–November 1944. During this time, German U-boats sank several merchant ships and four Canadian warships. There were several near shore actions involving the drop of German spies, or the attempted pick up of escaping POWs. Despite the 23 ships lost, this battle marked a strategic victory for Canadian forces as ultimately they managed to disrupt U-boat activity, protect Canadian and Allied convoys, and intercept all attempted shore operations. This marked the first time that a foreign power had inflicted casualties in Canadian inland waters since the US incursions in the War of 1812.

In the interwar years, poor economic conditions and a sense of security, engendered by the proximity of the United States and the traditional protection of the British Royal Navy, had resulted in the Royal Canadian Navy (RCN) being equipped with very few ships, especially for coastal defence. Upgraded to six destroyers just before the war, Canadian naval deployment gave priority to the North Atlantic convoy routes and responsibility which grew until the war's end when the RCN was the third largest allied naval power in the world, with 100,000 men and women and 400 vessels.

From the start of the war in 1939 until VE Day, several of Canada's Atlantic coast ports became important to the resupply effort for the United Kingdom and later for the Allied land offensive on the Western Front. Halifax and Sydney, Nova Scotia became the primary convoy assembly ports, with Halifax being assigned the fast or priority convoys (largely troops and essential material) with the more modern merchant ships, while Sydney was given slow convoys which conveyed bulkier material on older and more vulnerable merchant ships. Both ports were heavily fortified with shore radar emplacements, searchlight batteries, and extensive coastal artillery stations all manned by RCN and Canadian Army regular and reserve personnel. Military intelligence agents enforced strict blackouts throughout the areas and anti-torpedo nets were in place at the harbour entrances. Even though no landings of German personnel took place near these ports, there were frequent attacks by U-boats on convoys departing for Europe. Less extensively used, but no less important, was the port of Saint John which also saw matériel funnelled through the port, largely after the United States entered the war in December 1941. The Canadian Pacific Railway mainline from central Canada (which crossed the state of Maine) could be used to transport in aid of the war effort.

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Wikipedia