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 and helped generate support for the
United States declaration of war on Germany in April of the same year.