Zimmermann Telegram

The Zimmermann Telegram was a telegram written to the the government of Mexico by the foreign minister Arthur Zimmermann[?] of the German Empire during World War One on January 16, 1917. In it he proposed that if Mexico was to launch a pre-emptive strike on the United States it would have Germany's backing and would be rewarded with Texas, New Mexico and Arizona if the war was won. It also urged Mexico to mediate between Germany and Japan, to convince the Japanese to enter the war against the US. The telegram was decrypted by the codebreakers of the British Naval Intelligence unit, Room 40[?], under Admiral William R. Hall[?]. The British government, which wanted to expose the incriminating telegram, faced a dilemma: If it exposed the actual telegram, the Germans would be led to suspect that their code was broken, and if they did not, they would lose an important opportunity to draw the United States into World War I. The British knew that there existed a Mexican decrypted version of the telegram, and that, if they could lay their hands on it, they could pretend that the telgram was obtained as a result of espionage activity in Mexico, and not as a result of code breaking. Therefore, the British government contacted a British agent in Mexico, known only as Mr. H., who managed to get a copy of the Mexican version of the telegram.

The telegram was delivered by Admiral Hall to the British Foreign Minister, Arthur James Balfour, who in turn invited the American ambassador in Britain, Walter Page[?], and delivered the telegram to him on February 23rd.

On March 1, the US Government gave the plaintext of the telegram to the press, on April 2, the United States declared war against Germany. Previously German submarines had already attacked US ships near England, so the telegram was not the only cause of the war; it was, however, critical for US public opinion. It was perceived as especially perfidious that the telegram was first transferred from the US embassy in Berlin to the German embassy in Washington before being passed on to Mexico.

Although German, Mexican and Japanese diplomats, and the American pacifist and pro-German lobbies all denounced the telegram as a forgery, Zimmerman himself, in a startling move, confirmed its authenticity. After he had done so it became all but inevitable that the US would join the Great War.

The Zimmermann telegram as it was sent from the German ambassador in Washington to Mexico. Every word was encrypted into a four or five digit number, using a codebook[?].

The telegram as decrypted by the British Naval Intelligence codebreakers. The word Arizona was not in the German codebook and was therefore split into smaller parts.

The telegram, completely decrypted and translated.