Which of the following lead to the U.S. entry into World War I? A The sinking of the Lusitania B Zimmerman Telegram C Germany using unrestricted submarine (U-boat) warfare D All of the Above
D. All of the above. Germans torpedoed the Lusitania, which carried some American passengers, so that put everyone on edge. Then the Zimmerman Telegram was intercepted. It was a message saying that if Mexico aided the Germans in the fight against the U.S. if it came to that, then Mexicans could have back the American land that was taken from them (like Texas and New Mexico). This backroom deal greatly annoyed Americans. And Germany was kept sinking American ships with their unrestricted submarine warfare, so the U.S. declared that if Germany destroyed any more of their vessels that the U.S. would make war on Germany. The Germans would eventually violate these terms, and the U.S. would be thrust into war.