page_title: Military history of Canada during World War II
section_title: Battle of the Atlantic
hierarchical_section_title: Military history of Canada during World War II / Naval warfare / Battle of the Atlantic
caption_attribution_description: English: LAC caption&#160;: "Normandy, France. A 4.7-inch (12 cm) gun crew of the destroyer HMCS Algonquin piling shell cases and sponging out the gun after bombarding German shore defences in the Normandy beachhead." Allen, K. De Guire, R. Day G. Trevisanutto, G. Van Dyke, J. Irwin, A. Mathetuk, E.
context_page_description: The military history of Canada during World War II begins with the German invasion of Poland on 1 September 1939. While the Canadian Armed Forces were eventually active in nearly every theatre of war, most combat was centred in Italy, Northwestern Europe, and the North Atlantic. In all, some 1.1 million Canadians served in the Canadian Army, Royal Canadian Navy, Royal Canadian Air Force, and in forces across the Commonwealth, with approximately 42,000 killed and another 55,000 wounded.
  During the war, Canada was subject to direct attack in the Battle of the St. Lawrence, and in the shelling of a lighthouse at Estevan Point in British Columbia.
  The financial cost was $21.8 billion between 1939 and 1950. By the end of the war Canada had the world's fourth largest air force, and fifth largest navy. The Canadian Merchant Navy completed over 25,000 voyages across the Atlantic, 130,000 Allied pilots were trained in Canada in the British Commonwealth Air Training Plan. On D-Day, 6 June 1944 the 3rd Canadian Infantry Division landed on "Juno" beach in Normandy, in conjunction with allied forces.
context_section_description: The Battle of the Atlantic was the longest ongoing battle in World War II. Once Britain declared war on Germany, Canada quickly followed, entering the war on 10 September 1939, as they had a vested interest in sustaining Britain.
  Canadian security relied on British success in this war, along with maintaining national security, politically speaking, some felt it was Canada's duty to assist her allies. For example, the Canadian prime minister Mackenzie King had been utterly convinced that it was Canada's "Self-evident national duty" to "back Britain".
  Once World War II had erupted in 1939, Canada had a small navy. In 1939 Canada had seven warships. Once entering the war, Canada needed a naval reformation in order to keep up with and aid the British. On the outbreak of the war Canada had roughly 3,500 men supporting the RCN. In September 1940 "the RCN grew to 10,000 men".
  The Canadian government agencies also played a major role in the patterns of warfare in the Atlantic.  The Canadian Navies Division operated a network of naval control of shipping agents in the neutral United States from 1939 to 1941. These agents managed the shipping movements of British shipping in the United States, and also managed the growing United States Navy systems in regards to basic trade movements. Special publications on trade matters were supplied to the United States Navy from Ottawa in 1941, and by the time of Pearl Harbor American port directors were working with Ottawa as a team. Ottawa's job of studying trade movements and keeping track of intelligence was so effective and crucial that they were given the task of controlling shipping west of 40〫and north of the equator from December 1941 to July 1942, along with supplying the USN trade directorate with daily intelligence.
  Canada was also given the responsibility of covering two strategically key points in the Atlantic. The first is known as the "Mid-Atlantic Gap", located off the coast of Greenland. This gap was a very hostile point in the supply line which was very difficult to take control. With the use of Iceland as a refuelling point and Canada to the west, the gap was narrowed down to 300 nautical miles (560 km). "The Surface gap was closed by the Royal Canadian Navy [in 1943]. This Newfoundland Escort Force started with 5 Canadian corvettes and two British destroyers [manned by Canadian seamen], followed by other Canadian-manned British destroyers when available".
  The second task Canada was given was to control the English Channel during Operation Overlord (the Normandy landings). "On the 6th of June, 50 RCN escorts were redeployed from the North Atlantic and Canadian Waters for invasion duties".  Their tasks were to cover the flanks of the invasion to ensure submarine defence of the invasion fleet, also to provide distant patrols of the southern flank of the invasion area, and lastly to prevent submarine flotillas in the channel from gaining reinforcements. This invasion relied on the RCN to cover British and American flanks to ensure a successful landing on the beaches of Normandy.
  Canada saw enormous growth during World War II, going from a limited amount of warships to becoming the third largest navy in the world after the Axis powers were defeated and the role they played in aiding the USN in intelligence. Their primary role in protecting merchant ships from North America to Britain was ultimately successful, though that victory was shared with the major Allied powers. Throughout the war Canada had made 25,343 successful escort voyages delivering 164,783,921 tons of cargo. By the end of the war, German documents state that the Royal Canadian Navy was responsible for the loss of 52 submarines in the Atlantic. In return 59 Canadian merchant ships, and 24 warships were sunk during the battle of the Atlantic.
  "Canadians solved the problem of the Atlantic convoys." — British Admiral Sir Percy Noble
caption: Gun crew of HMCS Algonquin during a naval bombardment of German positions at Normandy, prior to the D-Day landings.
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