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Ninety-four years ago today, the American public found out that Zimmermann, Germany’s foreign minister, had sent a telegram directing the German ambassador in Mexico City to ask Mexico to join Germany in an alliance against the United States. The Zimmermann Telegram was as ill-advised as it was clumsily delivered. It helped propel the United States into World War I, a development that ultimately led to Germany’s defeat.
Zimmermann sent his telegram in mid-January 1917. The message ran fewer than 175 words and was breathtakingly simple—Mexico would get the lands it had lost seven decades earlier in the Mexican-American War in exchange for helping Germany:
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: we 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.
Zimmermann thought he was safe because he sent his telegram in code. There were two problems, however. First, the British intercepted the message. Second, the British had broken the German code, so they knew what Zimmermann was proposing.
News of the Zimmermann Telegram came at a crucial juncture in U.S.-German relations. When the war began three years earlier, Wilson had urged his fellow Americans to be “neutral in thought as well as action.” He worried not only that U.S. involvement in a war in Europe would run counter to more than one-hundred years of American foreign policy practice, but also that it would split the public. Although most Americans favored the Allied Powers—Britain, France, and Russia—German Americans, Irish Americans, Jewish Americans, and Scandinavian Americans all had reasons to favor the Central Powers—Germany and Austria. “We definitely have to be neutral,” Wilson noted in 1914, “since otherwise our mixed populations would wage war on each other.”
By 1917, intermittent German submarine attacks on passenger ships carrying American citizens and stories of German atrocities on the battlefield had eroded the American commitment to neutrality. On January 31, Germany announced that it was resuming unrestricted submarine warfare. Three days later, Wilson broke relations with Germany. On February 25, a German U-boat sank the British liner Laconia, killing twelve people including two Americans. By this time the British had shared the Zimmermann Telegram with Washington.
Wilson had the Zimmermann Telegram leaked so that it appeared in the press on March 1. His goal in making the proposal public was to pressure Congress to pass legislation authorizing the government to arm U.S. merchant ships. The leak failed to do that. Antiwar senators—who Wilson dismissed as a “little group of willful men”—successfully filibustered the measure. So Wilson did what many presidents, and particularly many modern presidents have done when they have failed to get their way on foreign policy—he decided he did not need congressional authorization after all.
Although the leak of the Zimmermann Telegram did not serve Wilson’s immediate political objectives, it further inflamed public passions against Germany and Mexico. The Mexican government showed no interest in the German proposal, but many Americans were prepared to think the worst about their southern neighbor. Over the previous year the U.S. Army, under the leadership of General John “Black Jack” Pershing, had crossed into Mexican territory seeking, unsuccessfully as it turned out, to capture Mexican revolutionary leader Pancho Villa, who had raided several U.S. border towns.
Some Americans understandably questioned the authenticity of the intercepted cable. That matter was settled by none other than Zimmermann himself. His answer to the charge that he was seeking an alliance with Mexico was simple: "I cannot deny it. It is true."
A little more than a month after the publication of the Zimmermann Telegram, Congress voted to declare war on Germany. The American portion of World War I had begun.