Professor Beverly Gage examines the Second World War in this Yale lecture, describing it as the most significant event of the twentieth century and tracing its causes and consequences for American foreign and domestic policy. The lecture extends the New Deal framework from the previous class into the international arena, considering how wartime mobilization reshaped the United States' role in the world. Recorded in Yale's Battell Chapel as part of the DeVane Lecture series America at 250: A History, the class is part of a one time course surveying United States history from 1776 to the present across lectures by three Yale historians.