When war broke out in Europe in 1914, the United States vowed to remain neutral. The American people had no interest in becoming entangled in European alliances and empires. President Woodrow Wilson, a progressive Democrat, won reelection in 1916 on the slogan “He kept us out of war.”
But that promise proved impossible to keep. Germany, which had temporarily paused unrestricted submarine warfare after the 1915 sinking of the passenger ship Lusitania, declared open season on American vessels in 1917.