The 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 empire, 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 third 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. The Second World War had significant cultural, political and economic effects on Canada, including the conscription crisis in 1944 which affected unity between francophones and anglophones. The war effort strengthened the Canadian economy and furthered Canada's global position.