Zimmermann Telegram
The Zimmermann Telegram (The Zimmermann Note) was a coded telegram dispatched by
the Foreign Secretary of the German Empire, Arthur Zimmermann, on January 19, 1917, to
the German ambassador in Mexico, Heinrich von Eckardt, at the height of World War I. It
instructed the ambassador to approach the Mexican government with a proposal to form an
alliance against the United States. It was intercepted and decoded by the British and its
contents hastened the entry of the United States into World War I.
The Telegram
The Zimmermann telegram as it was
sent from Washington to Mexico.
Zimmermann's message included proposals for German support of a Mexican offensive on the southern United States in
the event the United States attacked Germany. The telegram made it clear Germany did not want the United States
involved in the war, stating the belief that Britain would be forced to surrender soon. The Japanese government would
also join this new alliance in a possible conflict in the Americas. Germany, for its part, would provide financial assistance
and the restoration of former Mexican territories of Texas, New Mexico and Arizona. The telegram doesn't name the
other territories of California, Nevada and Colorado, which were formerly Mexican before 1848.
The Mexican answer
Later, a General assigned by Mexico's President, Venustiano Carranza, assessed the plausibility of a Mexican takeover
of their former provinces and came to the conclusion that it would not be feasible for the following reasons: retaking their
former provinces would mean war with the US; Germany would not have the capability to supply the arms and support
needed for seizure and defense of the territory; and Mexico would not be able to administrate the large Anglo population.
Carranza declined Zimmermann's proposals on April 14, by which time the US had declared war on Germany.
British interception
The telegram was intercepted and decrypted enough to get the gist of it by codebreakers Nigel de Grey, William
Montgomery and Admiral William R. Hall of the British Naval Intelligence unit, Room 40. This was made possible
because the code the Foreign Office used (0075) had been partially cryptanalyzed using, among other techniques,
captured plaintext messages and a codebook for an earlier version of the cipher captured from Wilhelm Wassmuss, a
German agent working in the Middle East.
The British government, which wanted to expose the incriminating telegram, faced a dilemma: if it boldly produced the
actual telegram, the Germans would know that their code had been 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 128 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, for onward transmission to their ambassador in Mexico, von Eckardt, by three separate routes. The
British had obtained it from just one of 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
the messages were encrypted, because as a matter of principle the United States did not at that time read other
countries' diplomatic correspondence and because, unlike Britain, the US did not 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 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 the American government that they had tapped US diplomatic communications.
The British solution
The British government guessed that the German Embassy in Washington, D.C. would send the message on to 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, they could pass it on to the United States government stating that they had
discovered it through espionage in Mexico. Therefore, they contacted a British agent in Mexico, known only as Mr. H.,
who managed to get a copy. In his autobiography, Sir Thomas Hohler, the British Ambassador in Mexico at that time,
claims to have been Mr. H. 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 Wassmuss codebook and could therefore be completely
decrypted.
The telegram was delivered by Admiral Hall to the British Foreign Minister, Arthur James Balfour, who in turn contacted
the U.S. 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 effect in the United States
The popular sentiment in the United States at that time was generally as anti-Mexican as it was anti-German. General
John J. Pershing had long been chasing the revolutionary Pancho Villa, who had carried out several cross-border raids.
This was at great expense to the U.S. 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 U.S. interests.
On March 1, the U.S. 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.
Arthur Zimmermann's speech
In an unexpected move, Zimmermann confirmed the authenticity of the telegram on March 3, and again in a speech on
March 29, 1917. The speech was intended to explain his side of the situation. He began that he had not written a letter
to Carranza but had given instructions to the German ambassador via a "route that had appeared to him to be a safe
one".
He also said that despite the submarine offensive, he had hoped that the USA would remain neutral. His proposals to
the Mexican government were only to be carried out if the US declared war, and he believed his instructions to be
"absolutely loyal as regards the US". In fact, he blamed President Wilson for breaking off relations with Germany "with
extraordinary roughness" after the telegram was intercepted, and that therefore the German ambassador "no longer had
the opportunity to explain the German attitude, and that the US government had declined to negotiate".
There was a ring of honesty in the speech since Zimmermann would have had occasion to reflect on the impact of the
telegram and its after effects in the meantime, but he was still prepared to defend its original ideas. However, it also
revealed he was seriously misinformed about the real strength of the United States vis-à-vis its southern neighbour; but
that was the fault of the German intelligence services.
War declared against Germany
The telegram began by stating, "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". Immediately after its publication there was an
outpouring of anti-German sentiment. Wilson responded by asking Congress to arm American ships so that they could
fend off potential German submarine attacks. A few days later, on April 2, 1917, Wilson asked Congress to declare war
on Germany. On April 6, 1917, Congress complied, bringing the United States into World War I.
German submarines had previously attacked US ships near the British Isles, so the telegram was not the only cause of
US entry into the war. 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.