In 1916, while a deadly war raged in Europe, President Woodrow Wilson successfully ran for reelection on the slogan, "He Kept Us out of War." But by April 1917, however, events had pulled the United States into what was then called the Great War, a conflict that Wilson subsequently declared a crusade to "make the world safe for democracy." Reacting to the unpopular nature of the war, the growing peace movement, the fear of radicalism, and the ethnic diversity of the nation, the U.S. government created a high-pitched propaganda effort designed to instill patriotism, promote the war, and reaffirm the cultural hegemony of traditional white Protestant values. The campaign fueled a jingoistic fervor that escalated into mass hysteria and vigilantism. The result was a harsh Americanization movement that demanded nothing less than total conformity. Especially targeted were ethnic groups from Southern and Eastern Europe.

Once the United States entered...