September 10, 1939 the Parliament of Canada declared war against the German Reich, marking the beginning of Canada's participation in the Second World War. The war officially began on September 1, 1939, with the German Invasion of Poland. Unlike in the First World War Canada was not automatically entered into conflict when Britain declared war, seven days prior. Canada also declared war on Italy (September 10, 1940), Japan (December 7, 1941), and other Axis powers. Canada's military was active in every theatre of war, though most battles occurred in Italy, Northern Europe, and the North Atlantic.
Over the course of the war, 1.1 million Canadians served in the Army, Navy, and Air Force. Of these more than 45,000 lost their lives and another 54,000 were wounded.The financial cost was $21,786,077,519.12, between the 1939 and 1950 fiscal years. The suffering and the hardships of war affected many Canadians at home and abroad. By the end of the War, Canada had the world's fourth largest air force, and third largest navy Additionally, the Canadian Merchant Navy completed over 25,000 voyages across the Atlantic. Canadians also served in the militaries of various Allied countries.