Zimmerman Telegraph A British political cartoon in early 1917 relates to the so-called Zimmerman telegraph between Germany and Mexico that called on Mexico to join the Central Powers and thereby regain its territory lost during the Mexican War. It spurred the United States to enter World War I. SHARE: Download: Full Size (0.11 MB) Tags: world war i Credit: Clifford K. Berryman VIRIN: 170305-O-D0439-001C.JPG Photo Gallery