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. 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. Out of approximately 625,000 Canadians who served in World War I, some 60,000 were killed and another 172,000 were wounded. 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. 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. In 1919, Canada joined the League of Nations independently of Britain, and the Statute of Westminster 1931 affirmed Canada's independence.