A brief video on World War I: how the war started, the U.S.' involvement, fighting the war, and the aftermath, with the Treaty of Versailles.
*Important Note: Italy was originally a member of the Triple Alliance when World War I started. After the war started in 1914, when the Triple Alliance became the Central Powers, Italy joined the Triple Entente. The Triple Alliance was originally a defensive pact against the Triple Entente. After Italy switched sides, the Ottoman Empire joined the Central Powers.