In this episode of APUSH for ALL, we trace how the United States moved from deep isolationism after World War I to full-scale involvement in World War II. We explore the trauma that shaped neutrality, the economic collapse that helped fuel Hitler’s rise, and Roosevelt’s cautious steps away from nonintervention. From the Neutrality Acts and Lend-Lease to Pearl Harbor and the two-front war that followed, this is a story of fear, memory, and political choice. We also examine the contradictions of wartime America, including Japanese American internment, and end with the difficult debate over the atomic bomb and war’s legacy.