“No account of the stirring episodes leading up to our entry into the World War can be considered complete without at least a reference to the one in which the Zimmermann telegram played the leading role.”

1938 study by the War Department Office of the Chief Signal Officer

The Zimmermann Telegram as it was sent from Washington to Heinrich von Eckardt (the German ambassador to Mexico)

The decryption of the Zimmermann Telegram is widely described as the most significant intelligence triumph for Britain during World War I. The story demonstrates that SIGINT can influence the course of History. Follow us on Twitter: @Intel_Today

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The Zimmermann Telegram was a secret diplomatic communication issued from the German Foreign Office on January 17 1917.

Zimmermann proposed a military alliance between Germany and Mexico in the prior event of the United States entering World War I against Germany. [Wikipedia]

The decoded telegram reads as follows:

We intend to begin on the first of February unrestricted submarine warfare.

We shall endeavor 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 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 in detail is left to you.

You will inform the President 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.

 Signed, ZIMMERMANN

The Zimmermann Telegram

Former SPY historian Thomas Boghardt returns to talk about his remarkable new account of the Zimmerman Telegram.

He has tapped fresh sources to provide the definitive account of the origins and impact of this German scheme.

Boghardt also corrects longstanding misunderstandings about how the telegram was sent and enciphered and provides a new account of how British intelligence was able to decipher it.

REFERENCES

The Zimmermann Telegram — Wikipedia

The Zimmermann Telegram — Prologue Magazine

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On This Day — The Zimmermann Telegram (January 17 1917)