German interventions in the Mexican Revolution

The German Empire had supported the Mexican government to mess up the exports of American arms. The Germans would also promise Mexico they would send them arms and money if President Huerta would have a war with the United States and would be returned to power. These conspiracies would be found by the United States.

Ypiranga Incident
The Ypiranga Incident was an Interception by the United States of a German ship named the SS Ypiranga that was carrying shipments of arms and ammunition that were going to supply the Mexican Government. When the U.S Navy captured it they forced the ship to turn back.

Zimmerman Telegram
The Zimmerman Telegra m was a secretive diplomatic plan and communication for Mexico and Japan to join the Central powers that would let Mexico gain all of the Southwest territories that Mexico had lost during the Mexican-American war of 1846-1848. The message would be intercepted by the British and would be shown to the United States. This would lead to the American declaration of war against Germany during World War I.

Alleged involvement in the Battle of Ambos Nogales
If true or not, the possibility of Germans at the border in Mexico was reasonable enough for a strong U.S. presence on the border of Nogales. There was a report of 2 Germans being killed during the Battle of Ambos Nogales but no evidence or proof is shown.