Late in 1916 the
Germans had planned to engage in unrestricted submarine warfare in an effort to
cut most sea borne supplies to Great Britain and thereby ensure her defeat.
However there
was the real risk that this plan would result in the United States joining the
war on the side of Great Britain so Germany worked on a rather novel counter
measure.
It was reasoned
that if Mexico could be encouraged to join the German side, and declare war on
America, then the US would be forced to commit a large slice of its military
effort to defending its southern border, thereby weakening any European
involvement.
Accordingly, on
January 19th 1917, a diplomatic telegram in coded form was sent via
Western Union from the German Foreign Secretary Arthur Zimmerman, to the German
Ambassador in Mexico, Heinrich von Eckardt, offering Mexico a deal. The
telegram as despatched consisted of irregular groups of 3, 4 and 5 numbers and
used the top secret German cipher “13040”, that unbeknown to the Germans had
been cracked by the British.
The telegram was
secretly intercepted by the British and sent to “Room 40”, their top-secret
code breaker group in the Admiralty. Here it was brought to the attention
of a shy and small man called Nigel de Grey, who was also one of the most
brilliant code-breakers in the world at that time. De Grey was a quiet and
self-effacing man nicknamed “The Door-mouse” by his colleagues. Working with two
other rather unlikely men, Dilly Knox and the Reverend William Montgomery, a
Presbyterian Minister, the trio succeeded in decoding the telegram. The result
was political dynamite. It read:
The British
presented this result to Edward Bell, Secretary of the US Embassy in Britain.
Bell was outraged and angered, and soon after, the situation was reported to
President Wilson, with the Americans regarding the incident as growing proof of
German hostility.
This event,
together with the sinking of the Lusitania in March 1915, resulting in the loss
of many American lives, undoubtedly played a significant role in finally
bringing the United States into Word War One in April 1917. This, in turn,
virtually guaranteed the eventual defeat of Germany.
De Grey helped begin
the great tradition of British code-breakers carried on with such distinction
by Alan Turing during World War 2 some 25 years later. “Room 40” would evolve
into the famous Bletchley Park in which de Grey was also to serve.
