Franklin Roosevelt initially charted a course of neutrality before the United States entered World War II. Yet Roosevelt believed that the rise of European dictatorships and their expansionist pursuits throughout the world threatened American national security. He saw signs of trouble early, but responding to antiwar sentiment from lawmakers and the American public, Roosevelt waited for a blatant enemy attack before declaring war. The Japanese attack on Pearl Harbor in 1941 provided that justification.

On the domestic front, World War II accomplished what Franklin Roosevelt’s New Deal could not. Prosperity and nearly full employment returned only after the nation’s factories began supplying the Allies and the United States joined in the fight against the Axis powers. Mobilization for war also furthered the tremendous growth and centralization of power in the federal government that had begun under the New Deal. Washington, D.C., became the chief source of authority to which Americans looked for solutions to problems concerning economic security and financial development. The federal government showed that it would use its authority to expand equal rights for African Americans. The war swung national power against racial discrimination, and various civil rights victories during the war served as precursors to the civil rights movement of subsequent decades. The war also heightened Mexican Americans’ consciousness of oppression and led them to organize for civil rights. However, in neither case, nor that of American Indians, did the war erase white prejudice.

At the same time, the federal government did not hesitate to trample on the civil liberties of Japanese Americans. The president succumbed to wartime antagonism against Japanese immigrants and their children. With China a wartime ally, Chinese Americans escaped a similar fate. Yet like white and black Americans, the Nisei displayed their patriotism by distinguishing themselves as soldiers on the battlefields of Europe.

The war brought women into the workforce as never before, providing a measure of independence and distancing them from their traditional roles as wives and mothers. Nevertheless, the government and private employers made it clear that they expected most female workers to give up their jobs to returning servicemen and to become homemakers once the war ended.

Finally, the war thrust the United States onto the world stage as one of the world’s two major superpowers alongside the Soviet Union. This position posed new challenges. In sole possession of the atomic bomb, the most powerful weapon on the planet, and fortified by a robust economy, the United States filled the international power vacuum created by the weakening and eventual collapse of the European colonial empires. The fragile alliance that had held together the United States and the Soviet Union shattered soon after the end of World War II. The Atomic Age, which J. Robert Oppenheimer helped usher in with a powerful weapon of mass destruction, and the government oppression that Fred Korematsu endured in the name of national security did not disappear. Rather, they expanded in new directions and shaped the lives of all Americans for decades to come.