In which John Green teaches you about American involvement in World War I, which at the time was called the Great War. The United States stayed out of World War I at first, because Americans were in an isolationist mood in the early 20th century. That didn't last though, as the affronts piled up and drew the US into the war. You'll learn the war's effects on the home front, some of Woodrow Wilson's XIV Points, and just how the war ended up expanding the power of the government in Americans' lives.