Answer
Step-by-step explanation:
The Zimmerman telegram was the telegram sent by German foreign minister Arthur Zimmerman to Mexico. Germany promised to help Mexico in recovering the territories lost to the United States. If the United States entered World War One, Mexico could recover its lost territories(Arizona, etc.). The telegraph was decoded by the British agents. The document was a piece of evidence that angered the Americans and helped the U.S to gain support for declaring war against Germany.