A coded message dispatched in January 1917 by the German Foreign Office to the German ambassador in Mexico. It instructed the ambassador to propose a military alliance between Germany and Mexico if the United States entered World War I against Germany. The offer included financial support and the recovery of territory Mexico had ceded to the U.S. in the past, specifically Texas, New Mexico, and Arizona.
The interception and subsequent publication of this communication significantly shifted American public opinion against Germany and contributed to the United States’ entry into World War I in April 1917. It highlighted the perceived threat of German aggression in the Western Hemisphere and undermined the isolationist sentiment prevalent in the U.S. at the time. This event is often studied in Advanced Placement United States History as a key turning point in U.S. foreign policy.
