Zimmermann Telegram

The Zimmermann Telegram (or Zimmermann Note) was an internal diplomatic communication issued from the German Foreign Office in January 1917 that proposed a military alliance between Germany and Mexico in the event of the United States' entering World War I against Germany. The proposal was intercepted and decoded by British intelligence. Revelation of the contents enraged American public opinion, especially after the German Foreign Secretary Arthur Zimmermann publicly admitted the telegram was genuine on 3 March, and helped generate support for the United States declaration of war on Germany in April. The decryption was described as the most significant intelligence triumph for Britain during World War I, and one of the earliest occasions on which a piece of signals intelligence influenced world events.

The message came in the form of a coded telegram dispatched by the Foreign Secretary of the German Empire, Arthur Zimmermann, on 19 January 1917. The message was sent to the German ambassador to Mexico, Heinrich von Eckardt. Zimmermann sent the telegram in anticipation of the resumption of unrestricted submarine warfare by Germany on 1 February, an act the German government presumed would almost certainly lead to war with the United States. The telegram instructed Ambassador Eckardt that if the United States appeared certain to enter the war, he was to approach the Mexican Government with a proposal for military alliance with funding from Germany.

The decoded telegram is as follows:

The Zimmermann Telegram was part of an effort carried out by the Germans to postpone the transportation of supplies and other war materials from the United States to the Allies of World War I that were at war with Germany. The main purpose of the telegram was to make the Mexican government declare war on the United States in hopes of tying down American forces and slowing the export of American arms. The German High Command believed they would be able to defeat the British and French on the Western Front and strangle Britain with unrestricted submarine warfare before American forces could be trained and shipped to Europe in sufficient numbers to aid the Allies. The Germans were encouraged by their successes on the Eastern Front into believing that they would be able to divert large numbers of troops to the Western Front in support of their goals.

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