The article analyzes the role that the Great War played in shaping Canada’s political identity and in building Canadian distinct position in international affairs. The first part of the article examines the negative and positive effects that the war had on Canadian social relations, economy, and its political status. The second part explains how the war experience and trauma gave rise to Canadian policy of autonomism, a political philosophy that dominated the last years of Robert Borden’s premiership and Arthur Meighen’s term of office. The article also elaborates on how Borden’s autonomism reshaped Canada’s attitude to Britain and to its empire, and how it initiated and accelerated the process of Canada’s transition from a dependent colony to an independent international actor.