Zimmerman Telegram

In 1917, a note in code, written by German Minister Arthur Zimmerman and sent to Mexico, was discovered by the British. The note suggested that if the US were to enter the Great War, Germany and Mexico should become allies, and Germany would help them regain lost territory in New Mexico, Texas, and Arizona. Predictably, this discovery created even more anti-German feelings. Previous incidents such as Germany's use of unrestricted submarine warfare had already stirred the American public, and the Zimmerman note probably pushed these anti-German feelings over the tipping point, and therefore became one of the reasons why the US declared war.