The monograph examines the socio-political history of Canada's participation in the First World War. Special attention is paid to the study of issues related to the entry of the North American dominion into the war, the political course of the conservative government of Robert Borden and the reaction of Canadian society to the efforts made during the war. The evolution of the Canadian army and Navy is analyzed, including the discussion on the introduction of universal military service. The article examines the position of Quebec and the French-Canadian nationalists led by Henri Bourassa on the issue of participation in the war.