World War I decimated millions and profoundly altered the course of world history. Postwar instabilities led directly toward a global depression and a second world war. The war sparked the Bolshevik Revolution, which led to the Soviet Union and later the Cold War. It created Middle Eastern nations and aggravated ethnic tensions that the United States could never overcome. And the United States had fought on the European mainland as a major power. America’s place in the world was never the same. By whipping up nationalist passions, American attitudes toward radicalism, dissent, and immigration were poisoned. Postwar disillusionment shattered Americans’ hopes for the progress of the modern world. The war came and went, leaving in its place the bloody wreckage of an old world through which the United States traveled to a new and uncertain future.