Cautious Autonomy: Mackenzie King’s Interwar Diplomacy in Postwar Canada

In the interwar decades, Canada underwent a gradual but decisive reorientation in its external relations, moving from a dominion governed primarily through British imperial structures to a state asserting an increasingly independent diplomatic identity. Much of this transformation occurred under the leadership of William Lyon Mackenzie King, whose cautious and incremental approach to foreign policy helped articulate a vision of Canada as a moderate, autonomy-seeking "middle-power." Although the term was applied more systematically only after the Second World War, King's “brand” of Canadian Nationalism laid the intellectual and institutional foundation for the middle-power model that later defined Canada's international role. This essay argues that King's interwar diplomatic choices were his pursuit of constitutional independence, his commitment to multilateral cooperation, and his preference for moderate, consensus-driven engagement, which played a central role in shaping Canada's post- 1945 contributions to the United Nations, peacekeeping, and collective security alliances. King's interwar legacy not only enabled Canada to project influence beyond its material capabilities but also established the normative framework through which Canada understood its global responsibilities in the post-war era.