Main article: Name of Canada

Early 20th century
1918 Canadian War bond posters depicting three French women pulling a plow that had been constructed for horses.

French version of the poster roughly translates as "They serve France–Everyone can serve; Buy Victory Bonds".

The same poster in English, with subtle differences in text. "They serve France—How can I serve Canada? Buy Victory Bonds".

Because Britain still maintained control of Canada's foreign affairs under the British North America Act, 1867, its declaration of war in 1914 automatically brought Canada into World War I.^[85] Volunteers sent to the Western Front later became part of the Canadian Corps, which played a substantial role in the Battle of Vimy Ridge and other major engagements of the war.^[86] Out of approximately 625,000 Canadians who served in World War I, some 60,000 were killed and another 172,000 were wounded.^[87] The Conscription Crisis of 1917 erupted when the Unionist Cabinet's proposal to augment the military's dwindling number of active members with conscription was met with vehement objections from French-speaking Quebecers.^[88] The Military Service Act brought in compulsory military service, though it, coupled with disputes over French language schools outside Quebec, deeply alienated Francophone Canadians and temporarily split the Liberal Party.^[88] In 1919, Canada joined the League of Nations independently of Britain,^[86] and the Statute of Westminster 1931 affirmed Canada's independence.^[89]
The Great Depression in Canada during the early 1930s saw an economic downturn, leading to hardship across the country.^[90] In response to the downturn, the Co-operative Commonwealth Federation (CCF) in Saskatchewan introduced many elements of a welfare state (as pioneered by Tommy Douglas) in the 1940s and 1950s.^[91] On the advice of Prime Minister William Lyon Mackenzie King, war with Germany was declared effective September 10, 1939, by King George VI, seven days after the United Kingdom. The delay underscored Canada's independence.^[86]
The first Canadian Army units arrived in Britain in December 1939. In all, over a million Canadians served in the armed forces during World War II and approximately 42,000 were killed and another 55,000 were wounded.^[92] Canadian troops played important roles in many key battles of the war, including the failed 1942 Dieppe Raid, the Allied invasion of Italy, the Normandy landings, the Battle of Normandy, and the Battle of the Scheldt in 1944.^[86] Canada provided asylum for the Dutch monarchy while that country was occupied and is credited by the Netherlands for major contributions to its liberation from Nazi Germany.^[93]
The Canadian economy boomed during the war as its industries manufactured military materiel for Canada, Britain, China, and the Soviet Union.^[86] Despite another Conscription Crisis in Quebec in 1944, Canada finished the war with a large army and strong economy.^[94]