On this day in 1917, the Zimmerman Telegram was exposed during the First World War, the main purpose of which was for Germany to encourage Mexico to declare war on the United States should they enter the conflict, which would have tied down U.S forces and slowed the export of U.S armaments.
The message came as a coded telegram dispatched by the Foreign Secretary of the German Empire, Arthur Zimmerman on 16 January 1917. Zimmermann sent the telegram in anticipation of the resumption of unrestricted submarine warfare by Germany on 1 February, an act which Germany predicted would draw the neutral U.S. into war on the side of the Allies. “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 message helped draw the United States into the war and thus changed the course of history. The telegram had such an impact on American opinion that according to David Kahn, author of The Codebreakers, “No other single cryptanalysis has had such enormous consequences.” Revelation of the contents outraged American public opinion and helped generate support for the United States Declaration of War on Germany in April of that year.