President Woodrow Wilson promised that American intervention into World War I would "make the world safe for democracy." But his dreams of a stable, democratic postwar order collapsed when Americans rejected the Treaty of Versailles and refused to join the League of Nations.

The First World War quickly devolved into a prolonged stalemate along the heavily entrenched Western Front. Millions of men died in futile efforts to capture the few hundred yards of territory that separated the opposing armies across "No Man's Land."