What was the Zimmermann Telegraph?
The zimmerman telegraph was actually the Zimmerman Telegram. It was a message telling Mexico to attack the US if the US attacked Germany. It also said that Germany would aid Mexico in regaining land that they lost to the US such as Texas, New Mexico, and Arizona. It was intercepted by the British though, and they immediately notified the US about it. It caused public outrage and sent the US to declare war against Germany.
