Part of the success of Bletchley Park between 1939 and 1945 was due to the success of the less renowned British codebreaking operations during the First World War between 1914 and 1918.
Tens of thousands of wireless and cable messages, sent by the armed forces and diplomats of Germany and its allies, were intercepted by the British who then broke the codes and ciphers which were intended to keep the contents of the messages secret.
Two British organisations were involved, the Admiralty’s ‘Room 40’ (named after one of its offices in the Admiralty’s Old Building in Whitehall) and the War Office’s MI1(b) (which worked closely with interception and codebreaking units on the Western and other war fronts).
Interception and codebreaking played a significant role in several of the major clashes during the First World War including the First Battle of the Marne in 1914 and, in 1918, the ‘Ludendorff Offensives’ and subsequent battles up to the signing of the Armistice; the naval battles including Dogger Bank and Jutland, and the submarine war at sea; and the air war which involved Zeppelin airships and aircraft bombing targets in Britain in what has been called the First Battle of Britain.
In addition interception and codebreaking activities played an important role in the fighting in the Middle East and the Eastern front.
The British codebreaking units also monitored German and Austrian diplomatic communications, notably in Spain, neutral Europe and North America. This gave the British an insight into German terrorist, sabotage and espionage operations as well as diplomatic relations.
Most significantly Room 40 intercepted a message sent in 1917 by the German Foreign Secretary, Arthur Zimmermann, to the German minister in Mexico. The ‘Zimmermann Telegram’ offered German support for Mexico in the ‘reconquest’ of Texas, New Mexico and Arizona from the United States. The objective was to distract the U.S. from entering the war on the side of Britain and France by provoking conflict on the border with Mexico.
Room 40 managed to break the code used to keep the message secret and once decoded informed Woodrow Wilson, the U.S. president, of its contents. The outrage in America when the telegram became public helped propel into the war a country reluctant to get involved in what it saw as an imperial European conflict. This came at a crucial time in the war as Russia, an ally of Britain and France, fell victim to revolution. Also both sides were becoming exhausted after three years of unremitting war. The decision of the U.S. to join the war swung the balance of forces sharply in favour of the Allies and against demoralised troops of Germany and Austria.
The Zimmermann Telegram was not the only factor behind American entry into the war – Germany’s resumption of ‘unrestricted submarine warfare’ in February 1917 also helped the U.S. to enter a war it had desperately tried to remain aloof from – but the Zimmermann Telegram helped make that decision.
Thus the interception of the Zimmermann Telegram can be said to have had a decisive effect in determining the outcome of the war. No single intercepted message had similar effect during the Second World War.
The existence of Room 40 became public knowledge in the years after the war (though details of the existence of MI1(b) were kept secret for much longer). This was quite different, of course, from what happened with Bletchley Park after the Second World War where the secrets of the breaking of the Enigma and Geheimschreiber cipher machines was maintained until the 1970s and 80s.
The public leaks about Room 40 were countered by the creation of a plethora of myths about the codebreaking organisation. These myths - many of which are still recounted today - played down the professionalism of the Great War codebreakers and emphasised that Room 40’s successes were due to lucky amateurism.
The creation of Room 40 has had many myths created about it. One account by a Royal Navy Admiral says that, at the start of the war, intercepted messages were sent into the Admiralty in London where they piled up on the desk of the Director of Naval Intelligence, Henry Oliver, who didn’t know what to do with them. One day early in the war he was about to leave his office to go for lunch with the Royal Navy’s head of naval education, Alfred Ewing, when it suddenly occurred to him that Ewing might have some ideas about what to do with the incomprehensible coded messages.
In fact, planning to create a codebreaking unit in the event of a major European war began in 1911 and Ewing had for some time been involved in the preparations. Far from being an accidental decision based on a lunch appointment, the creation of Room 40 was part of the process of getting the Royal Navy into shape for the war that suddenly loomed in late July and early August 1914.
A whole host of such myths about the birth and operations of Room 40 were created after the war to make it seem like small-scale amateur bumbling that luckily helped the nation pull through in its hour of need.
The Zimmermann Telegram episode also attracted a whole new series of myths designed to hide from senior German diplomats the fact that their communications with German diplomats in the Americas were being intercepted and decoded. Additionally, it was necessary to hide from the Americans that the British were tapping and decoding U.S. diplomatic communications. A series of fake claims was created to hide the true story of the Telegram and, again, these myths are still widely recounted in present day print and online accounts.
One of the similarities of the First World War codebreaking units and Bletchley Park in the Second World War was the critical role of the individuals who did the hard mental graft of making sense out of a series of coded and/or enciphered messages. As at Bletchley Park, Room 40 and MI1(b) had its share of brilliant eccentrics, such as ‘Dilly’ Knox, who was in fact active as a codebreaker in both wars (until his death in 1943). Knox was a true eccentric who did his best codebreaking work while lying in a hot bath – and he managed to persuade his superiors to have a bath installed in his office in the Admiralty.
But Room 40’s personnel also relied on brilliant but non-eccentric types, such as Nigel de Grey who played a key role in deciphering the Zimmermann Telegram. De Grey was also a central figure at Bletchley Park in the Second World War where he was a senior manager as deputy director. Among his responsibilities at Bletchley was managing the people using machinery to decode Enigma and Geheimschreiber enciphered messages, respectively the Bombe and Colossus.
One of the recent revelations about Room 40 is that during the First World War it developed a machine that could help break codes. Known as the ‘Hat Machine’ it accelerated the process of codebreaking of random (‘hatted’) codes tenfold, from one person working out ten codewords in a day to one machine uncovering one hundred code words in a day. Suddenly it was possible to reconstruct the otherwise fairly secure ‘hatted’ codes in a practicable timescale. This revelation brings the birth of mechanised codebreaking forward to 1916.
Thus, developments like the Bombe and Colossus can now be seen as having been conceived within the context of the ‘institutional memory’ of British codebreaking in the first half of the twentieth century. Bletchley Park was a product of the First World War.
Part of that institutional memory was that the success of Room 40 and MI1(b) required the staid conformist military to learn to accommodate the eccentrics and the non-conformist academics.
One officer in the First World War said of the codebreakers he had to liaise with in northern France, that:
Just like Bletchley Park a quarter of a century later.
By Paul Gannon