The telegram stated: "We intend to begin on the first of [February], unrestricted submarine warfare. In spite of this, it is our intention to endeavor to keep neutral with the United States. If this attempt is not successful, we propose an alliance on the following basis with Mexico: That we shall make war together and together make peace. We shall give general financial support, and it is understood that Mexico is to reconquer the lost territory in New Mexico, Texas and Arizona. The details are left for your settlement."
The telegram caused outrage in the United States and was a major factor in the decision by the United States to declare war on Germany in April 1917.