The Edmondson Blog

Arthur Zimmerman was the German foreign minister during the Great War. On 16^th January 1917, he sent his notorious telegram to the German ambassador in Mexico instructing him to approach the Mexican government with a proposal for a military alliance against the United States.

The telegram’s message was:

MOST SECRET

We intend to begin on the first of February unrestricted submarine warfare [against British shipping]. We shall endeavour in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal of an alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico and Arizona. The settlement detail is left to you. You will inform the President [of Mexico] of the above most secretly as soon as the outbreak of war with the United States of America is certain and add the suggestion that he should, on his own initiative, invite Japan to immediate adherence and at the same time mediate between Japan and ourselves. Please call the President’s attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace within a few months. Zimmerman.

Although the telegram was intercepted and decrypted by the British, it could not be publicised as that would have disclosed to the Germans that their code had been broken. Also, it could not be shown to the Americans as the British had obtained the original by illegally tapping an American private diplomatic telegraph.

However, the telegram had been sent via the German Embassy in Washington for forwarding to their embassy in Mexico City. The telegram to Washington was encoded using a newer, more difficult code. The British deduced that this code was not at the time in use at the Mexican Embassy, so the telegram would be transcribed into an older code in Washington; also, the onward transmission would be via the commercial telegraph system.

A British agent in Mexico, known only as Mr. H., bribed an employee of the commercial telegraph company to obtain a copy of the message, and, as expected, it was in an older code that could be easily decrypted.

The text of the telegram was given to President Wilson on 25^th February and, on 1^st March, the text was given to the press. Initially, the American public were sceptical but, in an unexpected move, Arthur Zimmermann confirmed the authenticity of the telegram in a speech on 29^th March.

On 2^nd April, Wilson asked Congress to declare war on Germany, which they duly did on 6^th April, bringing the US into the Great War.