President Woodrow Wilson was re-elected in 1916 with the help of the slogan “He kept us out of war.” The next year, however, he led the United States into the war on the side of the Allies. Which of the following contributed to American involvement in the war?
1. The sinking in 1915 of the British liner Lusitania
2. Germany stopped submarine warfare in 1917
3. A German attempt to turn Canada against the United States
4. Russia entering the war in 1917
