The Zimmermann Telegram

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Zimmerman Letter

This year marks the one hundredth anniversary of the United States’ entry into World War I. On 6 April 1917, at the behest of President Woodrow Wilson, a special joint session of Congress voted to declare war on Germany.

The United States’ entry into the war was precipitated by several events, including the sinking of the British passenger ship Lusitania in May 1915. The attack left 128 Americans dead and began to move American sentiments away from neutrality and against Germany. And, in early 1917, the Germans decided to engage in unrestricted submarine warfare against all commercial ships attempting to cross the German blockade of Great Britain. In March of that year, five U.S. ships were sunk by German submarines, pushing the United States even further toward war. However, perhaps the greatest impetus for U.S. entry into World War I may be the discovery of what has become known as the Zimmermann Telegram.

The U.S. states that were promised to Mexico in the Zimmerman Telegram.

Named for its originator, German Foreign Secretary Arthur Zimmermann, the telegram was intercepted by British intelligence. Decoding revealed a message to the German ambassador to Mexico, Heinrich von Eckardt, instructing him to propose a secret military alliance between Germany and Mexico in the event that the United States entered the war. The message read,

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.


President Woodrow Wilson asks Congress to declare war on Germany 2 April 1917, causing the United States to enter World War I. (Photo courtesy of the Library of Congress)

Mexico declined the alliance. However, the revelation of the telegram to the American public, coupled with the damage to U.S. ships from Germany’s unrestricted submarine warfare, drove the United States to unite with the Allies and declare war on Germany.

March-April 2017