The First World War bathed the new century in blood: Nine million lost their lives in a merciless war of attrition. A whole generation was traumatized by the horror of the trenches—and vowed that war would be a thing of the past.

Lost Peace revisits the popular hopes and experience in the years following World War I—and the looming threat of a new nationalism: despite Woodrow Wilson's promise of a "people's peace," old prejudices refused to die and nationalist passions again began to rise. Defeated nations were left out in the cold, resentful and unreconciled. Fascism and militarism spread while pacifist movements fought an increasingly unsuccessful rearguard action to preserve the dream of peace. By the late 1930s, people had to choose between avoiding war at all costs, or talking up arms to resist aggression. Fifty-five million lives were about to be lost in a second world war.

The people remember: Woodrow Wilson and the League of Nations, Yankee isolationism, German reparations, American volunteers fight the Spanish Civil War, invasions by Mussolini and Hitler.