Germany tried to get Mexico to attack the United States in World War I. The Germans knew the Mexicans weren’t too happy with the United States in the years prior to World War I. We were searching for Pancho Villa, and we had intervened in Mexican presidential politics. Germany also knew from experience that fighting a two-front war is a very difficult thing to do. It prevents a country from giving its full support to one area in the war. When a country has a two-front war to fight, that country must split its troops between the two fronts. Germany was planning to resume its sinking of ships without warning. This likely would bring us into World War I fighting against Germany. Germany wanted the United States to have to fight a two-front if we entered World War I.
Germany wrote a message, called the Zimmerman Telegram, to Mexico. Germany told Mexico that if Mexico attacked the United States and if Germany won the war, the Germans would require the United States to return much of the land we got from Mexico in the Mexican-American War. When the British intercepted this message, it was published in American newspapers. The American people were outraged. Americans knew if we went to war in World War I, we would be fighting against Germany.