On January 16, 1917, Germany dispatched the Zimmerman Telegram to Heinrich von Eckardt, the German ambassador to Mexico, instructing him to inform the Mexican government that Germany was willing to give the American Southwest back to Mexico if they declared war on the United States. The telegram, however, was intercepted by the British, and although the American public initially believed it to be a forgery, its authenticity was eventually proven and the resulting outrage hastened the U.S. entry into the war.