What Is the Zimmerman Telegram?

The Zimmerman Telegram was a cable from Arthur Zimmerman, an official in the German Foreign Office, to the German Ambassador in Mexico. It told the German Ambassador to tell Karanza that if the United States join the war with the Allies, that Mexico was invited to join the Central Powers and attack the exposed underbelly of the Colossus of the North. If Karanza did so, he was promised a generous supply of money and guns, and then when the Central Powers won the war, Mexico's reward would be their lost territories of Texas, New Mexico, and Arizona. So this was a promise to help Mexico avenge the humiliating invasion and dismemberment of their country back in 1848.