I. The document provides an overview of American involvement in World War I, beginning with Americans questioning neutrality and ending with the legacy of the war. II. Key events that pushed the US into the war included the sinking of the Lusitania, the Zimmerman Telegram, and attacks on American merchant ships. III. After declaring war in 1917, the US mobilized over 2 million troops who helped tip the balance on the Western Front, allowing the Allies to push back the Germans. Germany surrendered in 1918, ending the war.