The Bletchley Park Codebreakers (3 page)

Recruitment to Bletchley Park broke with one important but misguided precedent established during the First World War. Room 40 had made no attempt to recruit professional mathematicians, whose supposedly introverted personalities were thought to be too far removed even from the realities of daily life for them to engage with the horrendous problems posed by the First World War. Though a prejudice normally associated with arts graduates, this jaundiced view of mathematicians appears to have been shared by the Director of Naval Education, Sir Alfred Ewing, a former Fellow of King’s and Professor of Engineering at Cambridge, who seems to have been chiefly responsible for the recruitment from King’s (where his son-in-law remained a Fellow) of Adcock, Birch and Knox. Despite his own mathematical training, Ewing evidently considered the experience of classicists, historians and linguists in making sense of difficult and complex texts a more relevant skill for cryptanalysis than mathematical expertise. Similar prejudices continued to influence the recruitment of British cryptanalysts between the wars.

Polish military intelligence realized at the end of the 1920s that the attempt to break Enigma would require the recruitment of professional mathematicians (one of whom, Marian Rejewski, was to make the first major breakthrough in the attack on it). In the summer of 1938, Denniston finally reached a similar conclusion and began including a limited number of mathematicians among the ‘professor types’ who were being earmarked for Bletchley Park. Initially, however, the mathematicians were treated with considerable caution and some suspicion. The first mathematics graduate recruited by GC&CS, Peter Twinn of Brasenose College, Oxford, was told after he began work early in 1939, that ‘there had been some doubts about the wisdom of recruiting a mathematician as they were regarded as strange fellows,
notoriously unpractical’. Twinn owed his recruitment, at least in part, to his postgraduate work in physics. Physicists, he was told, ‘might be expected to have at least some appreciation of the real world’ – unlike, it was believed, most mathematicians.

Though the first wave of ‘professor types’ to arrive at Bletchley Park at the outbreak of war consisted chiefly of linguists, classicists and historians, it also included two brilliant Cambridge mathematicians: Turing from King’s and Gordon Welchman from Sidney Sussex College, who may originally have been earmarked because his mathematical brilliance was combined with skill at chess. According to the Cambridge Professor of Italian, E. R. ‘Vinca’ Vincent – probably the first ‘professor type’ to be selected – ‘Someone had had the excellent idea that of all people who might be good at an art that needs the patient consideration of endless permutations, chess players fitted the bill.’ Among other chess experts to arrive at Bletchley Park in the early months of the war were Hugh Alexander and Stuart Milner-Barry. Turing, Welchman, Alexander and Milner-Barry were jointly to sign the celebrated Trafalgar Day memorandum in 1941, which Churchill minuted, ‘Action This Day’. Whatever the original reasons for their recruitment, the first professional mathematicians at Bletchley Park made themselves indispensable so quickly that the recruiting drive was rapidly extended to mathematicians without a reputation as chess players.

Though GC&CS operated on a very much larger scale after its wartime move to Bletchley Park than it had done between the wars, at least one aspect of its original organization remained both of crucial importance and considerably ahead of its time. Denniston considered the ‘official jealousy’ which had prevented any collaboration between naval and military cryptanalysts from October 1914 to the spring of 1917 ‘the most regrettable fact’ in the history of British wartime Sigint. The establishment of GC&CS in 1919 was intended to avoid any repetition of such interdepartmental feuding. Within a few years of its foundation the new agency achieved the successful co-ordination of diplomatic and service cryptanalysis under overall Foreign Office control, though for most of the interwar years diplomatic decrypts yielded much more valuable intelligence than service traffic. That co-ordination, equalled by no other major Sigint agency abroad, was one of the secrets of Bletchley Park’s success.

For much of the 1930s the bitter rivalry between US naval and military Sigint agencies closely resembled that between their British
counterparts during the First World War. Each sought to crack independently the same diplomatic codes and ciphers in order, according to a declassified official history, to ‘gain credit for itself as the agency by which the information obtained was made available to the Government’. Though there was limited interservice collaboration at the end of the decade, the rivalry resumed after the breaking of the Japanese Purple diplomatic cipher by military cryptanalysts in September 1940, as naval codebreakers sought to prevent the Army from monopolizing Magic (Japanese diplomatic decrypts). After lengthy negotiations, an absurd bureaucratic compromise was agreed, allowing the military Signal Intelligence Service (SIS) to produce Magic on even dates, and its naval counterpart, OP-20-G, to do so on odd dates. This bizarre arrangement continued to cause confusion until the very eve of Pearl Harbor. On the morning of Saturday 6 December, a naval listening post near Seattle successfully intercepted thirteen parts of a fourteen-part message from Tokyo to the Japanese embassy in Washington, rejecting US terms for a resolution of the crisis and making clear that there was no longer any prospect of a peaceful settlement. (The fourteenth part was intercepted on the following day.) This critically important intercept was forwarded by teleprinter to the Navy Department in Washington. But since 6 December was an even date, the Navy Department was obliged to forward the message to the military SIS for decryption shortly after midday. SIS, however, found itself in a deeply embarrassing position since its civilian translators and other staff, as usual on a Saturday, had left at midday and there was no provision for overtime. Doubtless to its immense chagrin, SIS was thus forced to return the intercept to the Navy. While OP-20-G began the decryption, SIS spent the afternoon gaining permission for its first Saturday evening civilian shift. By the time the shift started, however, it was too late for SIS to reclaim the partly decrypted intercept from OP-20-G. And so, for the first time, on the eve of Pearl Harbor, the rival agencies produced Magic together. SIS was able to decrypt two of the thirteen parts of the intercepted Japanese message, though the typing was done by the Navy. The Sigint confusion in Washington, at one of the most critical moments in American history, highlights the immense importance of the successful resolution of interservice rivalry by GC&CS two decades earlier.

Equally essential to Bletchley Park’s success was Churchill’s passion for Sigint. By a remarkable – and fortunate – coincidence, Churchill
became war leader shortly after the first Enigma decrypts, one of the most valuable intelligence sources in British history, began to come onstream. Churchill’s passion for Ultra was equalled only by his determination to put it to good use. On the tenth anniversary in 1924 of the founding of Room 40, he had described Sigint as more important to the making of foreign and defence policy than ‘any other source of knowledge at the disposal of the state’. He was also well aware that, despite some successes during the First World War, the advantage gained by breaking German codes had sometimes been wasted. The indecisive battle of Jutland in 1916, the greatest naval battle of the war, might well have ended in a decisive British victory if the Sigint provided by Room 40 had been properly used by the Admiralty. Churchill’s own use of Ultra during the Second World War was, of course, far from infallible. The exaggerated sense of Rommel’s weakness in North Africa which he derived from his over-optimistic interpretation of Enigma decrypts, for example, made him too quick to urge both Wavell and Auchinleck to go on the offensive.

Even when due account is taken of Churchill’s limitations, however, he still remains head and shoulders above any other contemporary war leader or any previous British statesman in his grasp of Sigint’s value. That grasp depended on an experience of Sigint which went back to the founding of Room 40 early in the First World War and on his ability to learn from his mistakes in the handling of it. Had Churchill come to power in May 1940 without previous experience of Sigint, Bletchley Park might well have found his untutored enthusiasm for Ultra a dubious asset.

Great war leader though he was in most other respects, President Franklin D. Roosevelt was simply not in Churchill’s class when it came to Sigint. Despite a general awareness of the importance of wartime intelligence and a particular fascination with espionage, dating back to his experience of naval intelligence in the First World War, Roosevelt failed to grasp the importance of Sigint. Though Magic provided by far the best guide to Japanese policy during the year before Pearl Harbor, he showed only a limited interest in it. As well as sanctioning the absurd odd-even date division of labour between naval and military cryptanalysts, he also agreed to a further bizarre arrangement by which his naval and military aides took turns in supplying him with Magic in alternate months. This arrangement led to predictable confusion, including the suspension of the Magic
supply in July 1941, after FDR’s military aide breached Sigint security by absentmindedly leaving Japanese decrypts in his wastepaper basket. Not until November did the President finally lose patience and insist that Magic henceforth be communicated to him exclusively through his naval aide, Captain John R. Beardall. When shown Japanese decrypts, Roosevelt very rarely commented on them. Not until three days before Pearl Harbor did he discuss with Beardall the significance of any of the Magic revelations.

Churchill would never have tolerated the confusion allowed by Roosevelt in both the production and the distribution of Magic. He also showed far greater appreciation both of his cryptanalysts and the intelligence which they produced. Captain Malcolm Kennedy, one of the leading Japanese experts at Bletchley Park, wrote in his diary on 6 December 1941:

It would never have occurred to Roosevelt to ring up his cryptanalysts for the latest news. (Had he done so on 6 December, he would have discovered the confusion in the decryption of the fourteen-part Japanese telegram caused by the odd-even day arrangement.) Churchill also showed far greater determination than Roosevelt to ensure that his cryptanalysts had adequate resources. The American intelligence failure to provide advance warning of the Japanese attack on Pearl Harbor was due primarily to the difficulties in reading the latest variant of the main Japanese naval code, JN-25B. Though Magic contained no clear indication of plans for the surprise attack, undecrypted naval messages did. ‘If the Japanese navy messages had enjoyed a higher priority and [had been] assigned more analytic resources,’ writes the official historian of the NSA (the current US Sigint agency), Frederick Parker, ‘could the U. S. Navy have predicted the Japanese attack on Pearl Harbor? Most emphatically yes!’ JN-25B was not read to any great extent before Pearl Harbor because only a total of between two and five cryptanalysts had ever been assigned to work on it. The success in breaking Japanese naval codes, when
the number of cryptanalysts was increased after Pearl Harbor, was a crucial element in the US victory at Midway only six months later.

In the months before Pearl Harbor, when OP-20-G lacked the resources required to read JN-25B more fully, it did not occur to American naval cryptanalysts to appeal directly to Roosevelt. At exactly the same time, faced with a less critical though still serious shortage of resources, Bletchley Park’s leading cryptanalysts appealed directly to Churchill. The most junior of them, Stuart Milner-Barry, delivered the message personally to Number 10. Churchill’s response was immediate: ‘ACTION THIS DAY. Make sure they have all they want on extreme priority and report to me that this has been done.’

2

THE GOVERNMENT CODE AND CYPHER SCHOOL AND THE FIRST COLD WAR

MICHAEL SMITH

Britain’s codebreakers enjoyed a very successful First World War. Perhaps the best known of their achievements was the breaking, by the Royal Navy’s Room 40, of the Zimmermann Telegram, which brought the United States into the war. But even before Room 40 was created, on the orders of the then First Lord of the Admiralty, Winston Churchill, the Army’s MI1b had achieved considerable success against German military codes and ciphers.

The Army and Navy codebreaking units rarely spoke to each other, engaging in a turf war apparently fuelled by the Army’s resentment of the greater influence of the upstart in the Admiralty. Alastair Denniston, who for much of the war led Room 40, or NID25, as it was more correctly known, later bemoaned ‘the loss of efficiency to both departments caused originally by mere official jealousy’. The two departments finally began to exchange results in 1917, but there remained little love lost and the situation came to a head a year after the Armistice, when the question of whether or not there should be a peacetime codebreaking organization was under consideration.

Although there were inevitably some within government who were keen to axe the codebreakers as part of a peace dividend, there were many more who were just as eager to continue to receive the intelligence they were providing. It was decided to amalgamate the two organizations and a conference was held at the Admiralty in August 1919 to consider who should be in charge of the new body. The War Office wanted their man. Major Malcolm Hay, the head of MI1b, while the Navy was equally determined that Denniston was the worthier candidate.

But Hay appears to have overplayed his hand, insisting he was not prepared to work under Denniston, while the latter expressed a willingness to do whatever was asked of him. The generals were embarrassed by Hay’s attitude. It was not for junior officers to decide who they were or were not prepared to serve under. Denniston was subsequently given charge of what was to be known as the Government Code and Cypher School (GC&CS), with a staff of just over fifty employees, of whom only a half were codebreakers. ‘The public function was “to advise as to the security of codes and cyphers
used by all Government departments and to assist in their provision”,’ Denniston later recalled. ‘The secret directive was “to study the methods of cypher communications used by foreign powers”.’

GC&CS came under the control of the Director of Naval Intelligence, Admiral Hugh ‘Quex’ Sinclair, a noted bon viveur who installed the School in London’s fashionable Strand, close to the Savoy Grill, his favourite restaurant. The material it dealt with was almost entirely diplomatic traffic. Its main target countries were America, France, Japan and Russia, with the last providing what Denniston said was ‘the only real operational intelligence’.

‘The Revolutionary Government in 1919 had no codes and did not risk using the Tsarist codes, which they must have inherited,’ Denniston said. ‘They began with simple transposition of plain Russian and gradually developed systems of increasing difficulty.’ One of the reasons that the Bolsheviks were unwilling to use the old Tsarist codes was the presence among the British codebreakers of the man responsible for devising a number of them. Ernst Fetterlein had once been the Tsar’s leading code-breaker, solving not just German and Austrian codes but also those of the British.

‘Fetterlein was a devotee of his art,’ one of his former colleagues in the Russian
Cabinet Noir
recalled. ‘I was told that once, when he was sent to London with dispatches, he sat morosely through breakfast until suddenly a complete change took place. He beamed, began to laugh and jest, and when one of the embassy officials asked him what the matter was, confessed that he had been worried by an indecipherable word which occurred in one of the English telegrams he had deciphered. Someone had in conversation mentioned the name of a small English castle to which the King had gone to shoot and this was the word in the telegrams which had bothered him.’ He sported a large ruby ring given to him by Tsar Nicholas in gratitude for his achievements, which included deciphering a message that led to the sinking of a number of German ships in the Baltic in 1914. This had a valuable spin-off for Fetterlein’s future employers. The Russians recovered a naval codebook from the light cruiser the
Magdeburg
, which they passed on to the British.

Fetterlein fled from Russia during the October Revolution on board a Swedish ship. He and his wife narrowly evaded a search of the ship by the Russians, one of his new colleagues recalled him saying. ‘As the top cryptographer in Russia he held the rank of admiral and his stories
of the day the revolution occurred, when workmen stripped him of many decorations and bullets narrowly missed him, were exciting. It is said that the French and the British organisation were anxious to get him and Fetterlein simply sat there and said: “Well gentlemen, who will pay me the most?”’

The British evidently offered the most money. Fetterlein was recruited by Room 40 in June 1918, working on Bolshevik, Georgian and Austrian codes. ‘Fetty, as we addressed him, would arrive precisely at 9.30 and read his
Times
until 10 when he would adjust a pair of thick-lensed glasses and look to us expecting work to be given to him. He was a brilliant cryptographer. On book cipher and anything where insight was vital he was quite the best. He was a fine linguist and he would usually get an answer no matter the language.’

Fetterlein and his team, who included two female refugees from Russia and the occasional British Consul thrown out by the Bolsheviks, were easily able to keep on top of the relatively simple Bolshevik ciphers. This allowed them to ensure that the government of David Lloyd George was fully informed of the machinations of various elements of the Russian Trade Delegation, led by the Bolshevik Commissar for Foreign Trade, Leonid Krasin, which arrived in London in May 1920.

The messages decrypted by GC&CS were known as BJs because they were circulated in blue-jacketed files, as opposed to the red files used for reports from the Secret Intelligence Service (SIS), now better known as MI6. The Russian BJs showed Lenin telling Krasin that he must be tough with the British. ‘That swine Lloyd George has no scruples or shame in the way he deceives,’ said the Soviet leader. ‘Don’t believe a word he says and gull him three times as much.’ Lev Kamenev, the head of the Moscow Communist Party, was sent to London to take charge of the delegation. Very soon the decrypts showed that he was actively involved in the setting up of ‘Councils of Action’ across Britain, with the intention of using them, like the Russian Soviets, to prepare for a communist revolution in Britain. They also disclosed that the Russians were pouring money into the London-based
Daily Herald
newspaper.

To many of those in authority, it appeared that Britain was perilously close to its own communist insurrection. Field Marshal Sir Henry Wilson, the Chief of the Imperial General Staff, wrote a furious memorandum to Lloyd George. The telegrams showed ‘beyond all
possibility of doubt … that Kamenev and Krasin, while enjoying the hospitality of England, are engaged, with the Soviet Government, in a plot to create red revolution and ruin this country’. He received support from Admiral Sinclair, who surprisingly urged the Government to publish the decrypted telegrams. ‘Even if the publication of the telegrams was to result in not another message being decoded, then the present situation would fully justify it,’ claimed Sinclair.

Lloyd George then sanctioned the publication of eight of the telegrams as long as the newspapers claimed to have obtained them from ‘a neutral country’. But
The Times
ignored the official requests to keep the true source secret, starting its report with the words: ‘The following telegrams have been intercepted by the British Government.’ The Prime Minister called in Kamenev, who was due to return to Russia for consultations and told him there was ‘irrefutable evidence’ that he had committed ‘a gross breach of faith’. He would not be allowed back into the country.

Despite the
Times
report, and further press leaks after Kamenev’s departure, the Russians did not change their ciphers. There was no doubt that they were aware of what had happened. Krasin told Maxim Litvinov, the Bolshevik Deputy Commissioner for Foreign Affairs, that the British ‘had complete knowledge of all your ciphered telegrams … which had strengthened the suspicion that Kamenev is the teacher of revolutionary Marxism and was sent here with the express purpose of inspiring, organizing and subsidizing English Soviets’.

But the Russian ciphers were still not changed until three months later, when Mikhail Frunze, Commander-in-Chief of the Bolshevik forces fighting the White Russians in the Crimea, reported that ‘absolutely all our ciphers are being deciphered by the enemy in consequence of their simplicity’. He singled out the British as one of the main perpetrators. ‘All our enemies, particularly England, have all this time been entirely in the know about our internal military operational and diplomatic work,’ he added. A week later, the trade delegation in London was told to send correspondence by courier until they received new ciphers. They arrived in January 1921 and by April, Fetterlein had broken them.

The main source of the coded messages coming into GC&CS was the international cable companies. Under a section added to the 1920 Official Secrets Act, they were obliged to hand over any cables passing through the United Kingdom – a requirement that was quite openly
put down to the ‘general state of world unrest’ created by communist attempts to replicate the October Revolution across Europe. But many of the messages emanating from Moscow were intercepted by Royal Naval intercept sites – based at Pembroke and Scarborough – and Army sites at Chatham, Baghdad and Constantinople. Although GC&CS remained under Admiralty control, the vast bulk of the messages it decrypted were now diplomatic rather than military or naval and in 1922, Lord Curzon, the Foreign Secretary, decided that the Foreign Office should take charge of the codebreakers. One senior member of staff attributed this to a conversation with the French ambassador during which the Foreign Secretary ‘expressed certain views which did not coincide with the views of his colleagues in the cabinet’. These were duly passed back to Paris, decrypted by GC&CS and circulated among Curzon’s cabinet colleagues. The codebreakers were moved from their Strand headquarters to 178 Queen’s Gate and a year later again put under the control of Admiral Sinclair, who was now the Chief of MI6.

Despite his interest in the codebreakers’ intelligence product, Curzon showed little regard for its security. When further evidence of the Russian attempts to subvert Britain and its empire emerged in 1923, he used the deciphered telegrams to draft a protest note to the Soviet Government – the so-called Curzon ultimatum – which not only quoted the telegrams verbatim but made absolutely clear that they were intercepts, most of them passing between Moscow and its envoy in Kabul. These were almost certainly intercepted, and probably deciphered, in India where there was a well-established signals intelligence operation.

One of the leading cryptographers in India at the time was Captain John Tiltman, who was undoubtedly one of the best codebreakers in Britain, if not the world. He had been offered a place at Oxford at the age of thirteen but had been unable to accept. He subsequently served with the King’s Own Scottish Borderers in France during the First World War, where he won the Military Cross, and spent a year with GC&CS before being posted to the Indian Army headquarters at Simla in 1921. There was already a military intercept site at Pishin on the Baluchistan-Afghan border and Tiltman’s arrival coincided with the opening of another intercept station at Cherat, on the North West Frontier.

Tiltman later recalled that he was part of a small section of no more than five people based at Simla. It not only deciphered the
messages, but also garnered intelligence from the locations of the transmitters – which were determined by direction finding – from the way they operated, and from the routine communications, a process still known today as traffic analysis. ‘We were employed almost entirely on one task, to read as currently as possible the Russian diplomatic cipher traffic between Moscow, Kabul in Afghanistan and Tashkent in Turkestan,’ he said. ‘From about 1925 onwards, I found myself very frequently involved in all aspects of the work – directing the interception and encouraging the operators at our intercept stations on the North West Frontier of India, doing all the rudimentary traffic analysis that was necessary, diagnosing the cipher systems when the frequent changes occurred, stripping the long additive keys, recovering the codebooks, translating the messages and arguing their significance with the Intelligence Branch of the General Staff. I realize that I was exceptionally lucky to have this opportunity and that very few others have had the chance of acquiring this kind of general working experience. Between 1921 and 1924, I paid three visits to the corresponding unit in Baghdad and on several occasions, sitting amongst operators in the set-room of the Baghdad intercept station, worked directly on the red forms fresh off the sets, to the benefit not only of my own experience but also to the morale of the operators.’