From World War I to Operation Desert Storm, American policymakers have repeatedly invoked the "lessons of history" as they contemplated taking their nation to war. Do these historical analogies actually shape policy, or are they primarily tools of political justification? Yuen Foong Khong argues that leaders use analogies not merely to justify policies but also to perform specific cognitive and information-processing tasks essential to political decision-making. Khong identifies what these tasks are and shows how they can be used to explain the U.S. decision to intervene in Vietnam....