(19 January 1917)
A German secret telegram, containing a coded message from the German Foreign Secretary, Alfred Zimmermann, to the German minister in Mexico City. This instructed the minister to propose an alliance with Mexico, offering Mexico the territories lost in 1848 to the USA. The British intercepted the message and gave a copy to the US ambassador. The US State Department released the text on 1 March 1917, even as US–German relationships were deteriorating fast over submarine warfare. With the possibility of a German-supported attack by Mexico, the isolationists lost ground and on 6 April 1917 Congress entered World War I against Germany.
Subjects: Warfare and Defence — History.