Read The Secrets of Station X Online
Authors: Michael Smith
A new canteen capable of coping with 1,000 people at a single sitting was completed in the spring of 1942 and the builders began work on the larger concrete blocks which would replace the wooden huts. Throughout 1942, wave after wave of new recruits arrived at Bletchley and as the new purpose-built blocks were finished, in the latter half of 1942 and early part of 1943, there was a mass exodus into the new accommodation, although for security reasons the Hut numbers remained the titles of the various sections. The decyphered messages were sent to Z Watch in Hut 4 via Lampson Tubes, vacuum tubes that distributed papers around the Park and were known to the young girls who used them as the ‘spit and suck’.
‘We moved from Hut 4 which we loved into a horrible concrete building,’ said Sarah Norton, one of the debutantes working in the naval index.
To be totally perverse, we insisted on still calling the new block Hut 4. It had a long wide corridor which ended in a
T-junction. One afternoon, we decided to give Jean
Campbell-Harris
, who later became Baroness Trumpington, a ride in a large laundry basket on wheels that was normally used to move secret files. We launched it down the long corridor where it gathered momentum by the second. To our horror, at the T-junction, Jean suddenly disappeared, basket and all, through some double swing doors crashing to a halt in the men’s toilets. A serious reprimand was administered and our watches were changed so we were distributed among a more sober group. But this fortunately did not last long.
Their efforts were rewarded with a dramatic drop in the number of successful U-Boat attacks. But when
Shark
was lost in early March, following the introduction of a new short weather code, it looked as if a new blackout had begun. But by concentrating the
increasing
number of Bombes on the problem, and with the assistance of the first ‘Keen Machine’, Hut 8 broke the keys out within ten days.
From that point on, the new-found confidence in Hut 8 and the introduction of the much faster US four-wheel Bombes produced by the National Cash Register (NCR) company in Dayton, Ohio, ensured that Naval Enigma was never as difficult to break again. Relations with Op-20-G were now on a much firmer footing with all the old concerns and complaints removed by the joint interest in cooperating fully to protect the Atlantic convoys. Travis flew to America in October 1942 to meet Capt Carl F. Holden, the US Navy’s Director of Communications. They signed the so-called Holden Understanding, which committed both sides to cooperation on the breaking of the German naval cyphers, and in particular
Shark
. The daily keys and any messages that were broken were sent across the Atlantic on US bombers in what became known as ‘the Bomber bag’.
Joe Eachus, the US Navy liaison officer, began working in Hut 8 as a naval codebreaker.
My official duty was to report back to Washington what was
happening at BP. But that was not a full-time job, so I
undertook
to be a cryptanalyst while I was there. It had been a hobby of mine before the war. Some of the British had been in the FO as professional codebreakers for some years, but there were no US Navy guys who fitted that description. Everybody had been amateurs before. We were working on German Enigma and often-times we were reading stuff currently. Other times, something would happen and we were not and there was just a feeling of gloom around when we would go for a week without reading things, very downhearted. Then it got going again and you would see the smiles in the corridors. That was very noticeable that people there took a personal interest in the work. As an officer I was permitted to circulate a good deal more than most of the people who worked there, I had a good excuse, and there were a lot of academics there, particularly from Cambridge. I met professorial types on an equal footing in a way I would never have otherwise done. They were always a level or two above me. I found their attitude towards life very interesting. They were academics primarily and their personal life was secondary. My view had always been the other way round, my personal life was the primary thing and my
professional
life was a way of making a living.
The Americans became so adept at breaking
Shark
, largely due to the enormous number of four-wheel Bombes they built, that by the middle of 1944, with Bletchley fully involved in
providing
intelligence on the invasion of Europe, and with the British four-wheel Bombes incapable of matching the reliability of their American counterparts, the US Navy codebreaking organisation Op-20-G had completely taken over responsibility for
breaking
Shark
. The US Navy Bombes were even used to run menus for Hut 6 during the invasion of Europe, so good had relations between Op-20-G and Bletchley become. ‘In all they produced well over 100 machines which were of the utmost value to us, not only on Naval keys but also in Air and Army,’ Alexander said.
Indeed considerably more than half the total American Bombe time went on non-naval keys. Their whole hearted cooperation and readiness to use their Bombes for jobs in which they, as an organisation, had no direct interest was always very greatly appreciated by us; a great deal of our success on all keys (Naval, Air and Army) in the last two years of the war was due to their help.
The Allies had been lucky that Dönitz had chosen to
concentrate
on the eastern seaboard of America for the first part of 1942, Frank Birch said. If he had not, the U-Boats might well have pushed Britain to the brink of starvation.
The only comforting thought about those ten months is that at the time British resources were so meagre that even with all the information in the world only moderate immunity could have been obtained. By March 1943, when Special Intelligence was coming along strong, though not yet at full strength, the Germans had become incapable of reading our stuff and in the great showdown of that month the U-Boats were, as a result of Special Intelligence, driven off the convoy routes for six months.
The break into
Shark
was not the only deciding factor in the Second Battle of the Atlantic; the introduction of the Very Long Range Liberator aircraft, centimetric radar, the Huff-Duff shipborne DF system and new naval support groups,
including
aircraft carriers, made life altogether too dangerous for the U-Boats. But it was the ability to read the U-Boat messages that allowed the Allies to use these new-found resources to conduct a war of attrition against them, trading the loss of merchant ships for the destruction of a U-Boat, Beesly recalled.
Decisions had to be taken, never lightly, never without due thought, but taken none the less and one had to accept the
consequences. We were far removed from the sea but it did not require a great deal of imagination to picture tankers going up in flames, seamen being drowned or maimed, or invaluable cargoes being lost. The only possible way to treat the matter was as though it were a game of chess. Ships or U-Boats were pawns. When one of them was sunk it was removed from the board. One side or the other had gained a point, but the game was not over and one had to turn immediately to consider the next move, to try to save the remainder of one’s pieces and to take out some of one’s opponents.
Hut 8’s ability to read
Shark
also confirmed that the
B-Dienst
had been reading the Naval Cypher No. 3, ensuring that communications security was improved and the Germans were unable to predict the convoys’ routes. Nearly a hundred U-Boats were sunk in the first five months of 1943. As the battle swung toward the Allies, Harry Hinsley and the Hut 4 intelligence reporters detected increasing signs of nervousness among the U-Boat commanders. They began to report torpedo failures, made exaggerated claims, and expressed widespread fear of Allied aircraft. By April, their morale appeared to have gone into terminal decline, with the
Shark
decrypts containing ‘increasingly frequent references to their fear of air attack and to the efficiency of the Allied surface escorts in following up aircraft sightings’.
By May, the Allied successes against the U-Boats had soared to a level that threatened to wipe them out completely. On May 23, after hearing of the loss of the forty-seventh U-Boat that month, Dönitz ordered the Wolf Packs to be withdrawn from the Atlantic, giving the Allies the respite they needed to get supplies across to Britain in preparation for the invasion of mainland Europe. Bletchley itself was not only involved in the Battle of the Atlantic, it was also heavily involved throughout 1942 in providing intelligence on the fighting in North Africa; playing an important role in operations in the Mediterranean
against the Italian navy; providing information that was
critical
to the Double Cross System and preparing furiously for the invasion of mainland Europe. The 110 staff who arrived at Bletchley Park in August 1939 had swollen to 680 by the end of 1940 and by the end of 1942 to more than 3,500, of whom two-thirds were women.
So many of the people working at Bletchley Park were now women that Edward Travis set up a ‘Women’s Committee’ to advise him on ‘all questions affecting Women at the War Station’ and to ensure ‘the promotion of the well-being of all the women’ at Bletchley. The committee included
representatives
of all three women’s services plus Foreign Office civil
servants
, and its chairman, a Miss J. V. Wickham, was available at all times to offer advice and help to ‘any civilian woman who is in difficulty of any kind’.
T
he fighting in North Africa had begun with a sweeping victory over the Italians in early 1941 by General Archibald Wavell, the Commander-in-Chief Middle East. No German troops were in North Africa as yet and the Allied victory was the result of what was virtually an unopposed advance by British and Commonwealth troops against extremely limited
resistance
. Wavell did receive some assistance from Bletchley from Italian messages decyphered in Josh Cooper’s Air Section, with one message leading to the destruction of twenty-five Italian aircraft in a single attack. Bletchley was determined from early on that it should play as large a role as possible in
operations
in North Africa, arguing that
Ultra
would ‘in all
probability
produce an increasing amount of information of vital operational value’.
The idea of an outpost of GC&CS for the Middle East based in Cairo had first been proposed in July 1938 by the
pre-war
MI6 Chief and GC&CS Director Hugh Sinclair, but was resisted vehemently by the service intelligence chiefs in Cairo. In early 1940, there was a reluctance at Bletchley to dissipate its resources by sending anyone to Egypt, but by the summer the situation had eased and Bletchley sent a small team of codebreakers out to Cairo in July 1940, reinforcing them a few weeks later with Major Freddie Jacobs, the head of the GC&CS Military Section’s Italian codebreaking team, to form a military cryptographic unit called 5 Intelligence School. A ‘combined inter-service cryptographic bureau’ with the cover title of Combined Bureau Middle East (CBME) was finally set up, in
the former Fauna and Flora Museum at Heliopolis and with Jacobs in command, in November 1940.
Denniston arranged for Jacob to be in direct touch with Bletchley via Cuthbert Bowlby, the MI6 regional director in Cairo, for any discussion of cryptographic matters, and asked Jacob to send him a full round-up of what traffic was available there, noting that while the Bureau’s ostensible targets were Italian, Arabic and Russian ‘some day these may be expanded’.
Almost immediately after the Italians’ defeat, an Italian Air Force message referring to
Luftwaffe
escorts for convoys between Naples and Tripoli was decyphered at Bletchley Park. Hut 4 concluded from this that the convoys were carrying Germans and that Hitler must be sending troops to support his beaten ally. The codebreakers’ views were dismissed in both the Admiralty and the Air Ministry, and the report did not make its way to Cairo. A few days later, British troops had their first contact with the
Afrika Korps
.
General Erwin Rommel’s arrival in North Africa in
mid-February
1941 led quickly to the installation of a direct Special Signals Link to Cairo using Type-X cypher machines and on 13 March, the first direct transmission of an
Ultra
report from Bletchley to the CBME. Hut 3 could now send their reports direct to Jacobs who could then brief Wavell. The link had not had time to establish itself before Rommel began a rapid
offensive
that was difficult to predict.
The available Enigma decrypts appeared contradictory. The
Red
Enigma suggested that Rommel had been told to build up his strength before launching an offensive. But the regional
Luftwaffe
system used by
Fliegerführer Afrika
, broken by Hut 6 at the end of February and designated
Light Blue
, pointed to an immediate advance. Ignoring his orders from Berlin and despite only having a limited force, Rommel attacked immediately and was soon pressing home his advantage against the poorly prepared British troops, taking the Libyan ports of el Agheila
and Benghazi before surrounding the Australian garrison at Tobruk. But here he came to a standstill.
The problem for Freddie Jacob, the head of the GC&CS outpost in Cairo, was that only he and George Wallace, the commander of 5 Intelligence School, were allowed to handle the Hut 3 reports coming in from Bletchley, said Henry Dryden, who was originally sent out to Cairo from Bletchley to train codebreakers who had been working on Italian systems to break the German cyphers.
‘The first contact between British and German forward troops occurred at the end of February, and on 24 March el Agheila was reoccupied by the enemy,’ Dryden said. ‘At this point, I was invited by John Tiltman to go out to Heliopolis, “for a month, six weeks at the outside, old boy,” to train the Italian experts in breaking German systems.’ By the time he eventually got there, Jacob and Wallace were completely bogged down in trying to deal with the flood of
Ultra
messages that was coming in from Hut 3. ‘Because of their sensitivity, the messages were shielded from the eyes of the cypher officers by being encoded in a simple substitution before encypherment and dispatch from the United Kingdom,’ Dryden said. Jacob and Wallace ‘had been taking it in turns, on a twenty-four-hour basis, to decode them before they were sent in a locked box welded to the floor of a special car. As a high proportion of these messages reached Heliopolis during the night, these
officers
were glad of the 50 per cent reinforcement I provided.’
Given Rommel’s maverick disregard for his original orders, General Franz Halder, the Army Chief of Staff, sent his deputy, General Friedrich Paulus, to Tripoli to agree on a
strategy
, which was then passed back to Berlin, and to Bletchley Park, via the
Red
Enigma. The decrypts also disclosed that the failure to secure the port of Tobruk had stretched Rommel’s supply lines and left him desperately short of fuel.
Churchill pushed Wavell to take advantage of this
position
. But two attempted counter-offensives, forced on Wavell,
against his better judgement, by Churchill, failed in the face of the German 88mm anti-aircraft guns, converted by Rommel into an anti-tank role, which had an unrestricted view of their targets across the desert terrain. A single
Ultra
message which ought to have led British intelligence to question why Rommel needed so many armour-piercing rounds for his anti-aircraft guns passed unnoticed on 18 May 1941. The link from Bletchley Park was at any event of little use during this initial period of the war in North Africa, partly because the Hut 3 reporters were still learning their trade, partly because they were relying on
Luftwaffe
messages sent using the
Red
and
Light Blue
Enigma systems, which were the only relevant ones that Hut 6 could break, and partly because of the time it took to carry out the whole process of interception, decryption and the production of an intelligence report.
During fighting, the Bletchley Park reports rarely arrived in Cairo in what the military called ‘real time’. All too frequently the land battle had moved on before the intelligence could be given to commanders, said Ralph Bennett, one of the Hut 3 duty officers. ‘Very occasionally, the process could be completed in about three hours, but six hours may have been nearer the average.’
A Special Communications Unit (SCU) was sent out to Cairo in April 1941 to assist in the speedy transmission of
Ultra
intelligence to Auchinleck and his commanders in the field. It was the first of the SCUs to be sent on military operations, with many more to follow over the next four years. Based on the units first introduced during the Battle of France, it received
Ultra
reports direct from Hut 3, encyphered using the highly secure One-Time Pad system and sent via the RAF communications centre at Leighton Buzzard. It evolved into two separate
organisations
: the SCU conducting the communications between Hut 3 and the theatre of operations, and a separate Special Liaison Unit (SLU), providing the intelligence to commanders,
ensuring
that only those who were cleared to see it saw it, and that it
was never used without there being an alternative plausible way in which the information might have been obtained.
Momentary tactical advantage is not sufficient ground for taking any risk or compromising the source. No action may be taken against specific sea or land targets revealed by
Ultra
unless appropriate air reconnaissance or other suitable
camouflage
measures have also been taken. If from any document which might fall into his hands, from any message he might intercept, from any word revealed by a prisoner of war, or from any ill-considered action taken upon the basis of such
intelligence
, the enemy were given cause to believe that his
communications
are not adequately safe-guarded against interception, he would effect changes which would deprive us of knowledge of his operations on all fronts.
The failure of the second counter-offensive, codenamed
Battleaxe
, led Churchill to transfer Wavell to India, replacing him with Claude Auchinleck, known as ‘the Auk’. This
coincided
with
Ultra
’s first great contribution to the campaign. The
Luftwaffe
provided air escorts for the Italian convoys
resupplying
Rommel’s forces across the Mediterranean and some detail of the convoys was therefore carried on the
Light Blue
cypher. But the information derived from these intercepts was rarely good enough to allow the Royal Navy or the RAF to take action against the convoys.
Then in July 1941, Hut 8 managed to break an Italian Navy machine cypher, the C38m, which provided a flood of detailed information about the convoys. The
Light Blue
cypher gave
indications
of when a convoy was going to cross the Mediterranean and what it would be carrying while the C38m provided details of vessels involved and the route.
‘Between them, the two were mutually complementary sources of news about the convoys’ routes and their estimated times of departure and arrival at designated ports,’ said Bennett.
‘By the late summer of 1941, so many supply ships had been sunk that the Axis operations were severely curtailed and indeed faced complete strangulation.’
Since collating and analysing this information was a job in itself and the information it produced was required by both the Royal Navy and the RAF, it was carried out initially through collaboration between the Hut 4 ‘Z watch’ and the Hut 3 research section now led by Lucas.
‘From now until May 1942, longer-term research had to yield place to the more exciting duties of handling operational signals on Axis convoys to Africa,’ Lucas said. ‘The essential part of the work lay in the identification of covernames, or
covernumbers
, for turning-points on the routes.’ The routes taken by the convoys would have on average half-a-dozen legs on the journey to North Africa. The length of each leg could be worked out from the speed and sailing times specified in the message. The difficulty was in locating the turning points.
Pins were stuck into a string at distances equal to the lengths of the legs on the map. The string had its ends pinned to the ports of arrival and departure. Any intermediate points already known were also pinned. The rest of the slack was shifted about by trial and error to give the various alternative
possibilities
until a general shape of route was obtained that made sense and corresponded with our experience of Italian naval habits, for example a respectful detour to the east or west of Malta. Life in the research section was never dull but nothing again ever quite equalled the excitement of angling for Axis convoys with pins and string.
The convoy reports went to Cairo via the Special Signals Link and also to the navy in Alexandria and the RAF in Malta. The protection of the
Ultra
secret was paramount. In accordance with the regulations, no offensive action could be taken unless there was a clear secondary source, overwhelmingly created by
aerial reconnaissance. Even this could not be directed solely against the convoy lest the Germans noticed the change in routine reconnaissance patterns. But the material supplied by Bletchley Park allowed the Royal Navy and the RAF to wreak havoc among Rommel’s supply convoys.
‘
Ultra
was very important in cutting Rommel’s supplies,’ said Jim Rose, one of the Hut 3 air advisers.
He was fighting with one hand behind his back because we were getting information about all the convoys from Italy. The RAF were not allowed to attack them unless they sent out reconnaissance and if there was fog of course they couldn’t attack them because it would have jeopardised the security of
Ultra
, but in fact most of them were attacked.
By the time Auchinleck launched
Crusader
, a successful
counter-offensive
which relieved Tobruk in November 1941, the RAF and the Royal Navy were regularly sinking Rommel’s supply ships, causing him major problems. The arrival in Malta in late October of Force K, comprising the cruisers HMS
Aurora
and
Penelope
together with two destroyers, heralded a two-month period when supplies to the
Afrika
Korps
were brought to a virtual standstill.
The
Luftwaffe
keys had revealed Rommel’s own plans for an attack on Tobruk. But the first break into Army Enigma in North Africa confirmed that the failure of supply ships to get through made it unlikely that any attack would take place in the near future. The proliferation of Enigma keys as the Germans sought to improve signals security had led to a change in the nicknames given to them by Bletchley Park. The main keys that had already been broken retained their colour designation.
Luftwaffe
keys were now named after flowers or insects, Army keys after birds and Naval keys after fish.
Chaffinch
, as the new Army key was called, was broken after the capture from the headquarters of 16th Panzer Division on 28 November 1941 of the complete keys for November. It provided
details of the
Afrika Korps
’ shortages of food, fuel and water as well as ammunition for the 88mm ‘anti-tank’ guns. It also gave Auchinleck full details of how many tanks Rommel had at his disposal and useful information on the German dispositions. The captured documents also assisted in the break into a second
Afrika Korps
Enigma,
Phoenix
, albeit for only a week. These were the first operational German Army keys to be broken in a British Army area of operations and the Hut 6 successes against them were to be the first step of a major turning point in the way
Ultra
was viewed by British Army commanders. Up until that point, all the operational intelligence from Enigma had come either from
Luftwaffe
or German Navy keys, and while the former frequently provided important intelligence for ground forces commanders, it was not regarded as highly by the British Army as it was by the RAF.