Zimmermann telegram

The Zimmermann Telegram was a telegram dispatched to the government of Mexico by the Foreign Secretary of the German Empire, Arthur Zimmermann, on January 16, 1917, at the height of World War I.

The Telegram

Zimmermann's message included proposals for a German alliance with Mexico, while Germany would still try to maintain a state of neutrality with the United States. If this policy were to fail, the note suggested, the Mexican government should make common cause with Germany, try to persuade the Japanese government to join the new alliance, and attack the US. Germany on its part would promise financial assistance and the restoration of its former territories of Texas, New Mexico and Arizona to Mexico.

The Mexican answer

Later, a general assigned by Mexico's president, Venustiano Carranza to assess the realities of a Mexican takeover of their former provinces came to the conclusion that it would not work. Taking over the three states would almost certainly cause future problems and possibly war with the US; Mexico would also be unable to accommodate a large Anglo population within its borders; and Germany would not be able to supply the arms needed in the hostilities that would surely arise.

British interception

The telegram was intercepted and decrypted enough to get the gist of it by codebreakers Nigel de Grey and William Montgomery of the British Naval Intelligence unit, Room 40, under Admiral William R. Hall. This was made possible because the code the Foreign Office used (0075) had been partially cryptanalyzed using, amongst other techniques, captured plaintext messages and a codebook for an earlier version of the cypher captured from Wilhelm Wassmus, a German agent working in the Middle East.

The British government, which wanted to expose the incriminating telegram, faced a dilemma: if it baldly produced the actual telegram, the Germans would suspect that their code was broken; and if it did not, it would lose a promising opportunity to draw the United States into World War I – the message was sent during a period when anti-German feeling in the United States was running particularly high, following the loss of some two hundred US lives to German submarine attacks.

There was a further problem too — they could not simply confidentially show it to the United States government either. Because of its importance, the message had been sent from Berlin to the German ambassador in Washington, Johann von Bernstorff at their embassy for onward transmission to their ambassador in Mexico, von Eckardt, by three separate routes. The British had obtained it from just one these — the Americans had given Germany access to their private diplomatic telegraph in an effort to encourage President Wilson's peace initiative. The Germans were not afraid of using it because their messages were encypted by themselves and because as a matter of principle the United States did not at that time read other countries' diplomatic correspondence nor did they have any code-breaking capability. The telegraph cable went from the US Embassy in Berlin to Copenhagen and then via submarine cable to the United States via Great Britain (where it was monitored). For the British to reveal the source of the telegram to the United States would have meant also admitting to them that they tapped US diplomatic communications.

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 British solution

The British government guessed that the German Embassy in Berlin would send the message on the embassy in Mexico via the commercial telegraph system, and therefore a copy would exist in the public telegraph office in Mexico City. If they could get a copy, then could pass the telegram on to the United States government stating that they had discovered it through espionage in Mexico rather than the real source. Therefore, they contacted a British agent in Mexico, known only as Mr. H., who managed to get one. To the delight of the British code breakers, the message had been sent from the German embassy in Washington to Mexico using the older cypher in the Wassmus codebook and could therefore be completely decrypted — presumably because the German embassy in Mexico did not have the latest codebook.

The telegram was delivered by Admiral Hall to the British Foreign Minister, Arthur James Balfour, who in turn contacted the US ambassador in Britain, Walter Page, and delivered the telegram to him on February 23. Two days later he relayed it to President Woodrow Wilson.

The American response

The general sentiment in the USA was generally as anti-Mexican as it was anti-German. General John J. Pershing had long been chasing bandit-cum-revolutionary Pancho Villa, who had carried out several cross-border raids. This was a great expense to the US government, and Wilson was leaning towards discontinuing the search until new elections were held in Mexico, a new government installed, and a new constitution promulgated (a constitutional convention, which would adopt the 1917 Constitution of Mexico, was underway at the time). News of the telegram exacerbated tensions between the USA and Mexico, since such a treaty, if in place, would have hindered the election of a new Mexican government more friendly to US interests.

The telegram, completely decrypted and translated.

On March 1, the US Government gave the plaintext of the telegram to the Press. Initially the American public believed the telegram to be a fraud designed to bring them into the war on the Allied side. This opinion was bolstered by German, Mexican and Japanese diplomats, and by the American pacifist and pro-German lobbies, who all denounced the telegram as a forgery. However, in a startlingly unexpected move, Zimmermann confirmed its authenticity in public, two days after its publication.

Although the telegram began by stating that Germany was most interested in maintaining American neutrality while attacking its shipping, this confirmation of its basic enmity evoked an outpouring of anti-German sentiment. Wilson responded to this manifestation of German hostility towards the US by asking Congress to arm American ships so that they could fend off potential German submarine attacks. One month later, on April 2, 1917, Wilson asked Congress to declare war on Germany. Four days later, on April 6, 1917, Congress complied, bringing the United States into World War I.

German submarines had previously attacked US ships near England, so the telegram was not the only cause of the war; it did, however, play a critical role in swaying 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. Once the American public believed the telegram to be real, it became all but inevitable that the USA would join the Great War.

References

Room 40: British Naval Intelligence, 1914-1918, by Patrick Beesly. New York: Harcourt, Brace, Jovanovich, 1982 ISBN 0-15-178634-8
On Secret Service East of Constantinople, by Peter Hopkirk. Oxford University Press, 1994 ISBN 0-19-280230-5
The Zimmermann Telegram, by Barbara W. Tuchman, Ballantine Bools, 1958 ISBN 0-345-32425-0