Humanities › History & Culture The History of the Zimmerman Telegram The WWI Coded Message That Helped Change the Tide of Public Opinion in the U.S. Share Flipboard Email Print Photostat of the Zimmermann Telegram as received by the German ambassador to Mexico (Jan. 19, 1917). (Picture from the National Archives and Records Administration.) History & Culture The 20th Century People & Events Fads & Fashions Early 20th Century The 20s The 30s The 40s The 50s The 60s The 80s The 90s American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History Military History Women's History View More By Jennifer Rosenberg History Expert B.A., History, University of California at Davis Jennifer Rosenberg is a historian and writer who specializes in 20th-century history. our editorial process Jennifer Rosenberg Updated March 17, 2017 The Zimmermann Telegram was a coded message sent from Germany to Mexico in January 1917. Once the Zimmermann Telegram was intercepted and decoded by the British, the contents were leaked to the U.S. and helped change the tide of American public opinion and brought the U.S. into World War I. The Story of the Zimmermann Telegram The Zimmermann Telegram was secretly sent from German Foreign Minister Arthur Zimmermann to Germany's ambassador in Mexico, Heinrich von Eckhardt. The British managed to intercept this coded message and their cryptologists were able to decipher it. Within this secret message, Zimmermann revealed Germany's plan to restart unrestricted submarine warfare as well as offered Mexico territory from the United States if Mexico were to declare war on the United States. On February 24, 1917, the British shared the contents of the Zimmermann Telegram with U.S President Woodrow Wilson, who had been elected to a second term on the slogan "He kept us out of the war." The contents of the Zimmermann Telegram then appeared in newspapers five days later, on March 1. Upon reading the news, the American public was outraged. For three years, Americans had prided themselves on safely keeping out of World War I, a war they believed to be contained to Europe, which seemed far away. The American public now felt the war was being brought to their own land. The Zimmermann Telegram helped change public opinion in the United States away from isolationism and toward joining World War I with the Allies. Just a month after the contents of the Zimmermann Telegram were published in U.S. papers, the United States declared war on Germany on April 6, 1917. The Full Text of the Zimmermann Telegram (Since the coded Zimmermann Telegram was originally written in German, the text below is a translation of the German message.) We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal of alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico, and Arizona. The settlement in detail is left to you. You will inform the President of the above most secretly as soon as the outbreak of war with the United States of America is certain and add the suggestion that he should, on his own initiative, invite Japan to immediate adherence and at the same time mediate between Japan and ourselves. Please call the President's attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace.