Commander Malcolm Saunders, a former head of Bletchley Park's Hut 3 intelligence-reporting section, toured the Allied naval code-breaking centres in the autumn of 1943. He was extremely impressed with the FRUPAC operation at Pearl Harbor. It was a model for a large-scale codebreaking and signals intelligence production unit that was, if anything, more efficient than the system he had helped to set up at Bletchley Park, he said. This was the system that the British should aim for with Colombo.
Saunders was far less impressed with FRUMEL, where Fabian was apparently continuing to block co-operation. ‘The liaison with Colombo is not nearly as good as it should be,’ Saunders complained. ‘This is partly due to bad communications and insufficient staff at each end, but also due to the present lack of productivity of the Colombo unit, and to lack of a clear-cut statement of policy from Washington in this regard. The security aspect is constantly in mind and there is a constant suspicion of “leakage” to the American Military Authorities at Brisbane.’
The dislike of Fabian and his methods was not confined to the British and Australian codebreakers. Some of his own men found him difficult and believed his behaviour acted as a brake on their own operations. ‘In November 1943, when I reported to Melbourne, many of the Corregidor team were still serving at the station,’ recalled Forrest R. Biard, one of the FRUMEL codebreakers. ‘Most of them were pleasant to work with. One most certainly was not.’
Almost all of the ‘unpleasantness’ at Monterey stemmed from the fact that Fabian was junior to a number of the codebreakers working under him, said Biard.
Three of these officers were captains, while the officer in charge of them was a commander. This could have worked without tremendous friction had the officer in charge and his executive officer been well chosen. But somewhere up the line things went quite amiss. I hasten to add that the crypto-linguist captains who had the misfortune of having to serve under the despotic commander and his equally unfriendly executive officer, both quite junior to these captains, will always have my undying respect. They tolerated the daily and almost hourly insults so frequently given us in the linguistic section by their juniors, yet they still managed to perform their vitally important crypto-linguistical jobs most creditably. The insults some of us had to endure did not add to our ability to perform in that manner. Station Cast did its job and did it well, not because of the officers in charge of the station, but in spite of them.
In an effort to improve the situation Bletchley Park began to push hard for British participation in the dedicated US Navy signals intelligence circuit on which FRUMEL, FRUPAC and OP-20-G exchanged recoveries and discussed codebreaking problems. Harry Hinsley, the senior intelligence reporter within the Bletchley Park naval section, was sent to Washington to negotiate this new link. Travis and Birch also decided to send Hugh Foss to OP-20-G's new headquarters at the Mount Vernon Seminary to work alongside its Japanese codebreaking team. As head of Hut 7, Foss would be in a unique position to assess where each side might be best able to help the other and the posting had the added bonus of helping to solve his domestic problems.
These were so intractable that Foss and his wife Alison had even been offered two Wrens as home helps in an attempt to ensure he could keep his mind totally on the job, his cousin and colleague Elizabeth Browning recalled.
At first they had a local nanny but the muddle really got her down and she was glad to be called up and become one of the Wrens at the Park. She and I used to have one of the children to stay for a day or two at intervals so as to take some of the pressure off Hugh. After a time, Frank Birch said to me that there had been a conference about Hugh's home problems and they were thinking of transferring him to Washington in order to utilize his abilities more fully. I said I thought it was a most tactful way of improving things and so for a time Hugh was in the States and somehow Alison and the children survived. Nanny and I continued to lend a hand when we could. It was all very Heath Robinsonish but worked out fairly well in the end.
By late 1943, with the Battle of the Atlantic over and OP-20-G bearing the brunt of the attacks on the German Navy's Enigma ciphers, Hut 7 started to get time on Bletchley Park's large bank of Hollerith tabulating machines, drastically improving its ability to break JN25 messages. Hut 7 began to expand rapidly, with new sections being added. As the Allies gained the upper hand and the dislocation of Japanese forces increased, Peter Laslett was put in charge of a group looking for and recording all references in the Japanese messages to changes of codes and ciphers. Laslett, who had gained a first in history at St John's, Cambridge, had joined the Fleet Air Arm. But in mid-1942 he was ‘press-ganged’ by the navy into learning Japanese.
They sent me to the School of Oriental and African Studies and told us that if we couldn't read Japanese within a year we would be sent back to our ships. I had been on the Murmansk route, which was extremely dangerous, so I learned Japanese under sentence of being drowned. There were one or two of us billeted near Harley Street and we used to walk each morning to SOAS or to the British Museum where we did most of our studying. I had quite a time of it at large in London in bell-bottom trousers.
He was then commissioned and sent to Bletchley Park, where he was put in Hut 7, initially simply concentrating on decoding JN25.
The Japanese codes being book codes, breaking them was no kid's job. We had to look for repeated messages and tried to figure out the sentence structure to work out what the code groups meant. The greatest advantage was just occasionally when the Japanese repeated a message which the Germans had previously passed on a system which our colleagues at Bletchley Park had already broken. But in general it was rather tough and rather unsatisfactory, although it was interesting because the Pacific War was rather active. My great asset, I suppose, was that I was one of the very few people there who had actually served at sea, so I knew the type of terminology that might come up in any given situation. This, of course, was extremely useful in predicting what code groups might be expected to come next.
Isobel Sandison, a Foreign Office civilian who had passed one of the six-month Bedford courses in Japanese, worked in Laslett's section recording the radio references to various codes and ciphers. She was recruited in 1943 from Aberdeen University, where she had studied German.
When I arrived at Bletchley in September I was informed that the end of the German war was in sight and asked if eventually I would be willing to learn Japanese. The first few weeks we spent on general filing, scanning call signs, etc. in the department run by Jack Plumb – ‘Dr Plumb's Party’ on the door. Eventually the Japanese class began. There were about sixteen, all students or graduates in languages – classics or modern, a mix of naval officers, Wrens and civilians. Our teacher was John Lloyd, ex-Vice-Consul in Tokyo. The language was so different from anything we had encountered before that to begin with it seemed impossible. Working in pairs to help each other, we learned only to read the language – there was no need to be able to speak it convincingly. We practised on captured Japanese documents.
At the end of six months’ study we were split up among the different naval intelligence sections. Peter Laslett – my new boss – was a real enthusiast. We were reading, translating and interpreting very specific interceptions to do with codes, codebooks, keeping track of who held them, when they were used and changed. We passed on to the relevant people the information gleaned in what Peter christened ‘Japanese Cryptographic References’.
The remarkable atmosphere at Bletchley Park, where rank had very little meaning and people from all walks of life worked together as a close team, made a deep and lasting impression on all the code-breakers. But it was often more like a university campus than a top-secret wartime establishment, Laslett recalled.
Bletchley was a very informal place. It had the atmosphere of a mixture of Oxford and Cambridge High Table. We all had passes but the guards on the gate all knew us, so – although we did show our passes, as a matter of form – they would just wave us in because they knew who we were. Being a care
less sort of a fellow, at one point I lost my pass. One of the girls working for me forged me a pass in the name of Rosie Smarty-Pants and for the rest of my time at Bletchley I went past the security gate each day as Rosie Smarty-Pants. It was all informal security. We trusted each other completely. The fact that it worked and the secret was kept for so long is, I think, one of the most remarkable things about Bletchley Park.
18
AN ALLIANCE UNDER THREAT
The last few months of 1943 had brought dramatic improvements for the Colombo codebreakers. Their operations had been bolstered by the improved reception, the dramatic increase in staff and equipment and the promise of direct access to the US recoveries. But at the beginning of December they received worrying news. The new US liaison officer who was to control the link to the Americans was to be Commander Rudi Fabian, who had done so much to block cooperation.
Bruce Keith appealed to Bletchley Park to intervene, but Captain Edward Hastings, who was now in charge of liaison with both the British outstations and Washington, told him that he and his code-breakers would have to learn to live with the belligerent American. ‘With reference to the appointment of Fabian as a liaison officer, we must accept the selection made by Admiral Redman,’ said Hastings, ‘as he particularly dislikes any interference from British authorities and is well aware of the situation.’
Meanwhile, Harry Hinsley had arrived in Washington to negotiate a continuous and comprehensive exchange of information on a dedicated circuit. He had been deliberately picked for the negotiations because he was relatively junior and could therefore talk to his American counterparts at a working level where relations between the two sides were good rather than at a higher administrative level where too many political considerations appeared to come into play. ‘A low-level bloke had to be sent in the hope that agreement could be reached on the working level easily and would then get approval upstairs,’ said Frank Birch, now a deputy director of Bletchley Park. ‘If negotiations started upstairs someone would be bound to pull out the agreement of October 1942 in which we had expressed ourselves as content with strategical intelligence except west of 110° East.’
Hinsley did in the end have to negotiate with Admiral Redman and was distinctly unimpressed, describing him as ‘chock-full of grievances largely because he likes grievances for their own sake’. But the two sides agreed to set up a ‘comprehensive US–British circuit, to be called the BRUSA Circuit, as early as practicable between Washington, Pearl Harbor, Melbourne, Colombo and GC&CS, incorporating US naval and British circuits at present used for the dissemination of radio intelligence material’.
But the US Navy's reluctance, even at this late stage in the war, to co-operate fully with the British was illustrated by an escape clause which Redman insisted on inserting into the agreement, whereby ‘the extent to which radio intelligence information and recoveries can be exchanged between the BRUSA stations will continue to be dependent upon communication and other facilities available and on the need for such an exchange’.
The contrast between relations at Redman's level and those at the cutting edge of the codebreaking operations in OP-20-G and Bletchley Park could not have been starker at this moment. The Japanese Navy used two main cipher machines. The most important was the Coral machine issued to its naval attachés, which the Allied codebreakers were still struggling to break. But in August 1942 a similar machine – known to the Japanese as 97-shiki inji-ki-1 2-gata and to the Americans as Jade – was introduced for use by the Japanese Navy. Although never popular with the Japanese, it proved easier to crack than Coral and was solved in August 1943 by a team of US Navy codebreakers, including Lieutenant-Commander Francis A. Raven, one of the leading OP-20-G Japanese machine cipher specialists.
The American codebreakers now decided to make a renewed push to break Coral. OP-20-G moved Raven and the Jade system-breakers on to the Japanese naval attaché team, which already included Agnes Driscoll, a veteran machine cipher specialist who had solved the Orange and Red cipher machines for the Americans. It also asked Bletchley Park for any assistance it could give in terms of knowledge gained in the previous attempts.
Coincidentally, the British had already begun to increase their efforts to break the Coral material. The British intercept site at Sarafand in Palestine had been ordered to concentrate on the enciphered traffic, designated JNA20 by the Allies, and the Bletchley Park codebreaking team looking at the Coral machine had been moved into Hut 8, the naval Enigma section, which at the end of 1942 had achieved the impossible in breaking the Shark four-rotor Enigma cipher used by German U-boats in the Atlantic.
The move was ‘partly because naval section were very short of space and partly because it was thought that an exchange of ideas might benefit them and us’, said Hugh Alexander, the head of the naval Enigma section. In Hut 8 the JNA20 problem could be subjected to extensive examination by some of the best machine cipher specialists in the world, including Alexander himself. The British chess champion, Alexander was a brilliant codebreaker, second only to Tiltman. ‘We did quite a large amount of work with the JNA20 party,’ he recalled, ‘this starting a profitable association which lasted until well on in 1944.’
The Coral machine resembled its diplomatic counterpart Purple in that it had two typewriters plugged up to a central cipher machine, one for inputting the plain text, the other as output for the enciphered text. The cipher machine comprised three banks of twenty-six telephone stepping switches. The major cryptographic drawback suffered by the Japanese diplomatic machines, the decision to separate six letters off from the other twenty, had been removed, making life more difficult for the codebreakers. But although it had six different possible orders of stepping switches, only three of them were used.
Alexander and the other Hut 8 codebreakers began attacking the Coral machine using methods evolved during the breaking of Enigma. On the German machine the codebreakers had made the assumption – correct far more often than not – that, in the part of the message being studied, the ‘fast’ rotor of the Enigma machine would not have had the opportunity to move the medium rotor on a notch. The cryptographic effect of both the medium and slow rotors was therefore not changing at all. This reduced the odds to a much more manageable proportion. Since the banks of stepping switches on the Coral machine were designed to simulate the movement of rotors in a conventional machine, the same principle applied.
At the end of September the British began to make real headway and sent a detailed report on their progress to OP-20-G. ‘This report really marks the birth of the successful attack on the Coral,’ the official US history records. Both the British and the American code-breakers began to move forward rapidly on the basis of the Hut 8 report. They used a number of methods borrowed from the Enigma codebreakers to crack the Coral system, including Yoxallismus, a statistical process originally devised by Leslie Yoxall, one of the Bletchley Park Hut 8 machine cipher experts, to find the plugboard connections on the German Navy's Enigma machine. The US code-breakers also employed a piece of rapid analytic machinery similar in purpose to the Bombe, the machine developed at Bletchley Park by Alan Turing to match the enciphered Enigma traffic against potential cribs. The Rattler was an electronic ‘crib-buster’ built by a team of engineers from the Massachusetts Institute of Technology who had been drafted into the OP-20-G research section.
By the time Hugh Foss arrived in Washington in January 1944 the Allied codebreakers were closing in. The Americans immediately took the tall, red-bearded eccentric to their hearts, dubbing him ‘Lend–Lease Jesus’. With his experience in breaking the earlier Japanese naval attaché machine cipher, known as Orange to the American codebreakers, it seems unlikely that he did not have some form of contribution to make. But the major British input appears to have come from Alexander, who in February flew across to help in the final push and, according to US codebreakers, ‘contributed heavily’ to what was officially recorded as a joint US–British success. By 11 March, the codebreakers had solved the wiring
of the Coral machine and a few messages were read.
Not all the Japanese naval attaché messages used the Coral machine. There were also two codebooks in use. These were super-enciphered in much the same way as the main naval and army codes and were broken by Wrens and Foreign Office civilians working in Hut 7 under the supervision of Gordon Flintham, Eric Nave's former assistant on the China Station.
Edith Bennett was a leading Wren working on the naval attaché codebooks. Inspired by her father, who had served for twenty-eight years in the Royal Navy, she had volunteered to go to sea. Instead, she found herself being sent to Bletchley Park with a number of other Wrens.
I wanted to go into boat crew. I imagined myself sitting in the front of a boat and dashing through the waves. None of us had actually heard of Bletchley Park. It was in the middle of the country and I thought, Well, this is a Dickens of a place to send someone who joined the navy.
When we got there we had to sign the Official Secrets Act and it wasn't until we actually got into Hut 7 that we knew what we were going to do. You were told that you couldn't even speak to people in another office. It was completely taboo. Once you came out of the door at Bletchley Park all thought of work had to be forgotten and you didn't discuss it. My mother and father died without knowing what I did there.
The Wrens working on the Japanese material were given a three-month basic course on the Japanese language and codebreaking. ‘It was held in Bletchley Park itself. Hugh Foss was the one who suggested this and he took us for the first lesson. We were shown how to do characters just to put us in the mood, but, of course, it was more important that we knew what the characters were, like shipping, which was maru, and ki, which was how they denoted an aircraft.’
They first had to strip the additives off the enciphered five-figure messages.
The Emperor's Codes Page 26