Who was Prime Minister of Canada during World War II?

William Lyon Mackenzie King was Prime Minister of Canada during World War II. He served throughout the conflict, from Canada’s declaration of war in September 1939 until Japan’s surrender in 1945.

King returned to office in 1935 after the Great Depression and led the Liberal Party to victory again in the 1940 federal election. His government mobilized Canada’s industrial economy, armed forces and agricultural production for the Allied war effort. Canada supplied troops, food, munitions, ships and aircraft training.

One important issue was conscription. King tried to balance military demands with deep divisions between English- and French-speaking Canadians, especially in Quebec. His government introduced compulsory service for home defence in 1940 but delayed sending conscripts overseas until 1944.

King also strengthened Canada’s independent role in foreign affairs. In 1939, Parliament separately debated and approved Canada’s declaration of war, reflecting the country’s growing constitutional autonomy from Britain. He remained prime minister until 1948 and is Canada’s longest-serving prime minister.