Abstract: Understanding the role that Canada and its allies must play to respond effectively to the current challenges posed by the challenge to the liberal international order by revisionist great powers is no easy task. Rather than resorting to foresight, this roundtable aims to analyze in depth major historical issues that have marked international relations in order to draw lessons to guide Canada’s defense policy in the current environment of geopolitical contestation. The roundtable covers several case studies, including American isolationism during the multipolar order of the interwar period, tensions between allies during the Korean, Vietnam and Iraq wars, the deterrent posture of Canada and NATO during the bipolar order of the Cold War, and NATO’s adaptation strategies in the face of post-Soviet Russia, West Germany’s integration into NATO as a model for today’s Ukraine, the interrelationships between the European and Indo-Pacific theaters during the Cold War, and Canada’s relations with the Trump administration during its first term in order to anticipate the challenges posed by a possible second term.