During World War I, the Woodrow Wilson administration took unprecedented steps to mobilize public support for the war. In addition to a massive government propaganda campaign, Congress passed laws designed to silence dissent. Newspapers were censored, politicians were jailed, and mobs attacked those suspected of disloyalty. Some Americans organized to protest the erosion of democratic freedoms guaranteed by the Constitution, a group of rights that they called "civil liberties." Thus, while democratic freedoms were undermined during World War I, public concern over these policies inspired the beginnings of a twentieth-century movement to guard the right of Americans to criticize their government, even when their country is at war.

When President Woodrow Wilson called on Congress to declare war on Germany in April 1917, the government faced a formidable task. Millions of young men had to be drafted, equipped, trained, and shipped...