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Seventy Years Ago This Month at Bletchley Park July 1941To the aid of Russia. As the month of July 1941 progresses it gradually becomes clear that the Russian front is not going to totally disintegrate, despite the huge losses of men, material and land they are suffering. The dominant consideration in Churchill’s mind becomes how to provide them with aid. Britain signs a mutual assistance pact with Russia on 12th July, but there is little direct military aid that can be given. Churchill despatches military supplies to Russia via the Northern Passage, though the weapons are desperately needed for the defence of the UK and in North Africa. Bomber Command is ordered to mount an offensive against German cities with the intention of forcing the Luftwaffe to recall aircraft and anti-aircraft guns from the Eastern front to defend the homeland. And a stream of Intelligence information goes to Moscow though the Government does not disclose its source. With the failure of Operation Battleaxe an uneasy quiet descends on the North African desert as both sides lick their wounds. But at last there is good news at sea for in May Allied shipping losses had been more than 90 ships but in July fall to less than 30. Few know that this is largely because BP is at last reading the main German Naval Enigma North Atlantic key, Dolphin, used at this time by the U-boats. The Russian Front. The Russians face new threats as the front widens at both ends with an assault by Finish and German armies in the north on 1st July, and by the Rumania army in the south on the 2nd July. The Russians withstand the Finnish assault, though German troops continue the advance towards Leningrad. The frontier fortress of Brest-Litovsk finally surrenders after having held out for thirty days. On 27th July the Germans close their huge pincer movement on Smolensk taking 100,000 prisoners. Moscow is now being bombed every day. By the end of the month the Germans have reached within seventy miles of Leningrad, but hordes of the citizens come out to build defence works. Then on 30th July Hitler orders his Army Group Centre heading for Moscow to halt, in order to re-enforce the drive towards the southern oil fields. Russian Intelligence Sources. A steady stream of Intelligence flows from Britain to their Military Mission in Moscow and on to Stalin, though there is little reciprocation. On 7th July Britain warns Russia that the Germans are reading certain of the Russian Air Force codes and Naval messages in the Baltic, BP having learnt this unwelcome news from Enigma decrypts. But the British are not prepared to disclose the source, and Russia seems to believe the warning really means that it is the UK who is reading their signals. At least once, Churchill has to seek reassurance that the British Military Mission has not disclosed to the Russians the source of the excellent information. It is known, on his own admission, that John Cairncross in Hut 6 at BP did feed some information to Russia via the Russian Embassy when he felt that the British were providing too little information, in particular at the time of the German Kursk offensive in July 1943. It seems quite possible that he was not aware of just how much was flowing through the Military Mission. But Cairncross, as an Army Staff Captain, did not come to BP until March 1942 though he may have had access to Ultra material before then when he was private secretary to the Chancellor of the Duchy of Lancaster; Lord Hankey exercised a general supervision over the Intelligence Services and saw all Cabinet papers. John left BP at his own request in the summer of 1943 for a post in MI6. There has been some suggestion that there was another Russian spy, code-name Baron, working at BP before Cairncross arrived but he has never been identified and may well not have existed. It is known from the Venona papers, that a Hut 3 Enigma decrypt was leaked to Russia in May 1941 but it seems more likely that the person who did this was Leo Long in the German order-of-battle section of the War Office. (In February 1943 the US Army equivalent of BP, Arlington Hall, started to work under the code-name Venona on a back-log of Russian encyphered “diplomatic” messages, in due course with some assistance from a small team at BP that had started work in June 1943 on the messages of a Russian-controlled partisan network). By whatever route, it would seem that somehow Russia did learn about BP and its work; the KGB knew Station X as Kurort. The Russians had very effective spy networks, the “Red Orchestra”, and in particular the “Lucy” network in Switzerland where the radio officer was Allan Foote, a British citizen. In a post-war book he said that the information the Lucy ring passed on was of such a high quality that it must have come from a senior source in the German High Command itself. Such a source has never been satisfactorily identified, and because of this exceptional quality of Intelligence it is often suggested that the British Government chose to use this Lucy ring route to “leak” the information from BP to the Russians. Unfortunately for this lovely story, the Official Historian states explicitly “There is no truth in the much-publicised claim that the British authorities made use of the Lucy ring to forward intelligence to Moscow”. The Intelligence War in North Africa. Driven on by an ever-optimistic and impatient Prime Minister, General Wavell had mounted two premature offensives in May and June 1941 in the Western Desert, designed to throw Rommel’s troops back from the Egyptian frontier and relieve the besieged Tobruk. Following the failure of Operation Battleaxe on 17th June, General Wavell was replaced by General Auchinleck, and an uneasy peace descends on the desert while both sides try to build up their strength for the next battle. Both in the BP Intelligence teams, Hut 3 & Hut 4, and in the Intelligence staff in Cairo a process of learning how to make use of the excellent information provided by Ultra is in progress. Not least is the problem of how to communicate the information to the senior military commanders in a way that will help them to make good use of it. Because BP is reading the Luftwaffe Red and Light Blue keys, Cairo is well informed on some aspects of the German military situation, but up to this time still has all too little information on Rommel’s Africa Corps. The RAF in North Africa is having some difficulty in learning how to use Ultra without making it obvious that they have access to such priceless information. Rebukes have followed when they make some use of the information for which there is considered to be no satisfactory alternative source. But ever since he arrived in North Africa, Rommel has been making excellent use of our disgracefully poor field signals security; in particular he always knows where our armour is located. The British supply line from the UK round the Cape is extremely long, but Rommel, who has much shorter supply lines across from Italy, is handicapped because the Africa Corps is now very much a side-show to the mighty struggle in Russia. And with the breaking of the Italian naval Hagelin C-38m machine by BP in June 1941, excellent information is becoming available to the British about virtually every one of the supply convoys for Rommel, and so his shipping losses are increasing steeply. Between May and September 1941 the stock of fuel for the Luftwaffe in North Africa sinks by 90%, as we learn from Enigma. In July 1941 the Cairo team succeed in breaking the Africa Corps medium-grade field cypher, and learn how to take advantage of the running commentaries of the reconnaissance units of the two Panzer divisions that Rommel now has in the desert. German movements were ordered along “thrust lines” signalled by coded map-references. The British learn how to read these by laying down shelling in likely spots and then the mobile Y units listen in to the Panzer shelling reports that use these coded map references. (This process was known as “gardening”, and came to be employed by BP for the dropping of mines in German home-waters in order to generate reports coded in Enigma from their coast-guards which provided excellent cribs). Gradually the team develops into that superb Intelligence arm of the Eight Army under Brigadier Edgar Williams that was in due course to serve General Montgomery so well for the rest of the war. Breaking of the German Police codes. From the early days the Military Section in Hut 5 at BP had been reading the German Police codes. Their leader, Colonel John Tiltman was established in a room upstairs in the Mansion that had once been the nursery of the Leon family where the walls were still decorated with “Peter Rabbit” wall-paper. In December 1940 a party from BP had joined a French team at La Ferté-sous-Jouarre on the Marne for work on the police codes. The fall of France had led to a significant loss of intercept capability of the German police signals, though BP continued to break a considerable number of the German police messages, which were largely enciphered in a double transposition hand-cypher. (The Gestapo arm of the Police used an Enigma key, called TGD by BP which they never broke. According to the Official Historian its non-solution is “to this day one of the classic mysteries of Hut 6”. But BP had been reading the SS Enigma key, Orange, used for general administration purposes including the concentration camps, since December 1940; the concentration camp death-returns became such a regular feature that BP used them as a crib for breaking Orange). With the invasion of Russia more police signals were received on better frequencies for interception and the Germans introduced a new hand cypher key that was soon broken by BP. So from July 1941 onwards John Tiltman’s military section was reading a considerable number of messages from the German police in Russia. On the 18th July they read a police message reporting that 1,153 “Jewish plunderers” had been shot. There followed a regular flood of messages enumerating the shooting of Jews and partisans. Tiltman’s section began sending reports on these atrocities to MI14, the research section of Whitehall’s Military Intelligence service. There was very little interest shown so BP gave up sending the regular messages on the execution of the Jews, though Churchill himself did respond in August in a characteristic manner. (There was one response from a pedantic Colonel in MI14, restricted to pointing out that BP was mixing together the statistics from” two entirely different parts of the German police service”). But throughout the war BP continued to produce weekly summaries of police operations behind the Russian front. The work at BP on the Police cyphers used some 500 people by the peak in the summer of 1944. One reason for maintaining this large effort was that the material often provided cribs for breaking Enigma keys. Another was that the type of hand-cyphers used by the Police was very similar to that used for the field communications of the German Army and Air Force and as a fall-back reserve when Enigma was unusable at times of crisis as happened in Russia and then in Europe in 1944. It came to be appreciated that this team at BP provided excellent training for new cryptographers before they transferred to work in the field. Whether it really was sensible to employ so many people on such relatively unimportant work must remain a matter for argument. Hut 8 reads the Main German Naval cypher. At last Hut 8 is reading regularly and with little delay the main German naval key, Dolphin. In July this is with the aid of a key sheet captured in May from the U-110, but now they believe they have mastered how to do it cryptographically. The elation in the Admiralty is immense as at last they can track the U-boats. Codebreakers Rewarded? One day in July 1941 Alan Turing, Gordon Welchman, and Hugh Alexander, the three BP codebreakers who had made perhaps the most distinguished contribution to the regular breaking of Enigma, are summoned to the Foreign Office; apparently each receives a cheque for £200 from the hand of Sir Stuart Menzies (“C”, the head of the Secret Service) – a considerable sum in those days. There is a long tradition of the military leaders of this country receiving a substantial financial reward after a great victory, and sailors had at one time received a share of the “prize money” when an enemy vessel was captured and sold off, but for civil servants this financial reward must have been without precedent. (Gordon Welchman was formally in the armed services though he said he was never properly enlisted until the day he went to be demobbed!). But no doubt the Secret Service had a discreet fund for rewarding those who had made a secret contribution to the country’s welfare. One can see the hand of Churchill in this matter, no doubt frustrated by being unable to publicly honour in the normal way those individuals who he, but very few others, well knew were making such a crucial contribution to the war; it is said that the codebreakers shook hands with Churchill himself on that day. It would seem that there was an even more improbable but well attested post-script to this award; on the way back in the train from London to Bletchley the three are discussing what to do with such new-found wealth. The eccentric but brilliant Alan Turing declares that the only safe thing to do with money in the current circumstances is to convert it into bullion. Good as his word he gets his £200 converted into silver, buries it in a near-by wood – and promptly forgets where he has buried it! There are those who swear that they went on expeditions with Alan to find the bullion, equipped with a metal detector that Alan designed & built himself, sadly to no avail. Prof Donald Michie, founder of the Turing Institute, was one who told the tale, but then he was famous for holding the first chair in the world devoted to artificial intelligence, that aspect of science of which Alan might be considered to have been the god-father. Once during a night watch the Director of BP, to his considerable embarrassment, stumbled on his senior scientist, Alan Turing, playing chess with the youngest member of his staff, Donald Michie. Donald played a distinguished part in the breaking of the Fish codes and development of Colossus. The Bletchley Park Trust welcomes the preparation of these notes, but the authors are responsible for the statements and the views expressed. |
