The Zimmermann Telegram was an internal diplomatic communication issued from the German Foreign Office in 1917. The proposal was intercepted and decoded by British intelligence. Revelation of the contents enraged American public opinion and helped generate support for the United States declaration of war on Germany in April of the same year. The message came in the form of a coded telegram dispatched by the Foreign Secretary of the German Empire, Arthur Zimmermann, on January 11, 1917, and 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 February 1, an act the German government presumed would almost certainly lead to war with the United States. The telegram instructed that if the US appeared certain to enter the war, he was to approach the Mexican Government with a proposal for military alliance with funding from Germany.