The use of Enigma decryption was not confined to intercepted enemy messages, it also played an active role throughout the war in operations designed to deceive. And the most crucial of these was the Pas de Calais gambit of 1944, part of the preparations for D-Day. Indeed, it was reckoned by Bletchley Park veteran and renowned historian Harry Hinsley that, without Bletchley, the D-Day landings might well have been a catastrophic failure and the forces could have been “thrown back into the sea.”
Here is how they did it. Over the space of several months, German Intelligence operatives found themselves monitoring a gigantic new military formation which was apparently termed the First United States Army Group (FUSAG). German Intelligence was also receiving word of the Twelfth British Army, whose many divisions looked poised to move into Norway, into Sweden, into Turkey, Crete, and Romania. The Allies, it seemed, were massing. German Intelligence gradually gained an impression that the Allies were planning a substantial cross-channel assault. And no area was more threatened than the Pas de Calais, the point at which the Americans—apparently—planned to enter and then swarm into France.
It was all, of course, a vast and elaborately planned deception, which had the effect of taking German attention off the real target of the Normandy beaches. And on top of this, noted Ralph Bennett, “bombing and sabotage cut enough landlines in northern France in the weeks before D-Day to force a proportion of useful intelligence on to the air.” Landlines were a problem for Bletchley because communications made by telephone could not be intercepted. Now, thanks to the work of Bletchley, the Allied commanders were able to see that the lies had worked, receiving confirmation via broken messages from various corners of the German military machine.
With the coming of D-Day, the work of Bletchley was reaching its climax. As one veteran recalled, the approach of Operation Overlord changed the atmosphere of the Park quite dramatically, not least because there was a sudden travel ban: “This was a miserable restriction, as most of us had nowhere to go for our weekend off. We were also forbidden to eat at the cafeteria and had to eat in a Nissen hut by ourselves and the food was much worse. Our work intensified under pressure.”1
One Wren kept staccato diary notes of this pressure, recording such memories as: “Monday 12th June—Started the nightmare,” “Tuesday 13th—Gosh, what a day!” and “Weds 14th—Hectic day!” Another recalled the unexpected results of being briefed:
We started at midnight and the Head of the Watch said, “Before you young ladies sit down tonight, I want you to come and have a look at this map.” He showed how all round the south coast the army, navy, and air force were grouped ready for invasion the next morning. He said, “Because of that you will not be allowed to speak to anyone outside of the room tonight or go on your canteen break.”… How did they think three Wrens in the middle of Bletchley were going to warn Hitler we were about to invade?2
These quibbles aside, Bletchley played its part on June 6, 1944, even as the Allied armada was setting sail across the Channel. Various messages from the Germans, involving U-boats and reports of parachute landings, were decoded, translated, and sent to the relevant authorities all within the space of half an hour. Although the precise details of the landings were secret, it was clear that something very significant was about to happen. Mavis Batey recalls of the buildup: “I remember that we knew when D-Day was coming because I can see myself going up to London on a train from Bletchley and thinking ‘I suppose I am the only one on this train who knows D-Day is tomorrow.’”
For codebreaker Harry Hinsley, D-Day involved him sitting firm behind his desk for more than twenty-four hours. The climax was marked by an important telephone call from Downing Street. First a woman asked him to confirm that he was Mr. Hinsley, then he heard Churchill’s voice asking: “Has the enemy heard that we are coming yet?” Hinsley assured the Prime Minister that the first Bletchley decrypts of German messages were coming on the teleprinter.
A couple of hours later, Churchill called Hinsley again: “How’s it going? Is anything adverse happening yet?” After forwarding more decrypts, Hinsley finally allowed himself to leave his desk, return to his billet and go to bed.
But in general terms, 1944 was by no means the end. Following D-Day, there was a lethal German technological weapons breakthrough, targeted on London. Indeed, later in the year, one of the last V-1 flying bombs to land came down very close to the Stanmore bombe outstation, although damage was kept to a minimum because of the blast wall that had been built to protect the machines.
Sarah Baring was working at the Admiralty. Under the forty feet of reinforced concrete, known as the Citadel, that sat atop this maze of passages and offices, the prospect of lonely night watches, although not entirely welcome, did offer one consolation. As she recalled: “It was horrible sitting in my flat alone with these bloody rockets crashing down. And the short walk to the safety of the Citadel…was too tempting to resist…it may have looked like Lenin’s tomb to some people. But I got to love the old dump and was amused to notice on bad nights the portly figure of the First Lord of the Treasury prowling the corridors in his bright red silk dragon-patterned dressing gown.”
Mavis Batey vividly recalls the V-1 flying bombs and the means by which the codebreakers at Bletchley Park sought to thwart them. “We were working on double agents all the time, giving misinformation to their controllers. And because we could read the Enigma, we could see how they were receiving this misinformation. One of the things when the V-1s started was that the double agent was asked to give a report to the Germans on where the rockets were falling. Because of course they were wanting them to fall on central London.
“At that point, the bombs were falling in central London so intelligence here wanted them to cut out at a different point. So this double agent was instructed to tell his masters that they were falling north of London. The result of this was that the Germans cut the range back a little and as a result, the rockets started falling in south London. Just where my parents lived.”
In this case, it seemed that to Mrs. Batey at least, ignorance was preferable to any other state; for security reasons, she knew nothing of this double-cross operation, or the messages that confirmed its success. “I had no idea and it is just as well that I didn’t. So when I saw the devastation at Norbury, I did not know that it had anything to do with anything I was doing. It really would have been a terrible shock to know that.”
The decisive turning of the war brought Bletchley into a new phase. Plans were being made for the allocation of encryption work after the conflict. Nevertheless, as the Allies took France and it appeared, finally, that the Germans were in retreat, the work rate intensified dramatically at the Park, for the very fact of turning fortunes meant that the volume of German-encoded traffic had risen dramatically. On top of this, German Intelligence had further tightened security around the encryptions. In fact this was one of the most tiring phases at the Park. By September 1944, Hut 8 was recording naval decrypts at a peak rate of about 2,200 a day.
Happily, as the weeks of the Allied assault wore on, the effect on German communications staff was deleterious; as a result, attention to security became more slapdash. By this time, the Colossus technology was firmly bedded in. A further six of the revolutionary machines were delivered to the Newmanry and a new block, Block H, was built to house them. More were to follow as the year went on.
Indeed, for this final stage of the conflict, personnel numbers at Bletchley had almost doubled from what they had been just two years previously. As well as the codebreakers and the Wrens, there were large support teams (including 152 house staff—cleaners, handymen, etc.) and a transport section comprising 169 drivers, some fifty of whom were women. Transport didn’t just deal with dispatches—there was also, according to one who worked in the department, “a Wolseley and a Hillman…we would wait in the lounge for the phone calls. Whoever was there answered and you could find yourself going down Watling Street to St. Albans with dispatches or to the Admiralty.”
There was no letup in pace, or indeed in focus and concentration. In December 1944, Hugh Alexander set up Naval Section IIJ specifically to make further inroads into the main Japanese naval code. And there were still outbreaks of tension between the military and Bletchley Park. That same month the Park found itself being blamed for failing to give warning of a surprise attack in the Ardennes, when the British and Americans found themselves facing fourteen infantry and seven Panzer divisions along a 75-mile front. The assault was termed by some as “the most notorious intelligence disaster of the war.” Those who worked in Hut 3 defended themselves with the explanation that they had picked up word of an imminent assault—and indeed a date—but there was nothing in the transmissions that could have indicated a location.
Part of the problem, it seemed, was that the Germans had used skillful deception—misdirection in the matter of troop deployments—as well as a tactic of radio silence. Moreover, the amount of decrypt material that Bletchley could harvest had decreased; rather than relying on radio transmissions, the Germans, back in their own territory, were using landlines once more.
This ever-increasing intensity of work took its toll at the Park; by December 1944, it was estimated that the sick rate was running at 4 percent, rather higher than normal. In the earlier years of the war, such intensity would have been tempered with the enthusiasm of youth. One can see all too easily, though, how the strict rota system, combined with the unremitting focus of the often repetitive and dull work, would have a corrosive effect. It is often said that for ordinary soldiers, any conflict is composed of moments of sheer terror and exhilaration, and the rest of the time of solid boredom. In the case of Bletchley, there was little in the way of exhilaration or terror.
Nevertheless, by January 1945, those in Hut 6 were cracking more German army signals than ever before, under the keys “Puffin” and “Falcon.” And even though the tide was flowing so strongly, the work did not let up. Against the backdrop of the Yalta conference of February 1945—at which Stalin assured Churchill that there would be free elections in Poland after the war—there was another massive codebreaking setback when the Luftwaffe started to implement a new system of changing call-sign encryptions on a daily basis, and the frequencies every third day. Thankfully, some of the more experienced codebreakers and traffic analysts were still able to detect the individual traits of some individual enemy operators, which gave a way in to each code.
On the night of April 29, those on duty at Bletchley Park found themselves witness to Hitler’s increasing desperation. The Führer telegraphed Field Marshal Keitel from his bunker with three questions. “Where are Wenck’s spearheads? When will they advance? Where is Ninth Army?” Keitel’s response was that all such forces were either stuck fast or completely encircled.
One might imagine a buildup of tremendous excitement in the huts at this time. But in fact, the events leading up to VE Day brought with them, surprisingly, an increase in security precautions. In late April, just days before German capitulation, the staff of Hut 3 were being told in memos that any decrypts involving mass German surrenders were to be extremely restricted in terms of circulation. On top of this, Director Edward Travis sent out a memo forbidding celebratory telegrams being sent out—unless they were in extremely special circumstances, in which case they first had to be presented for his approval.
Why the anxiety? First, the war with Japan was still going on. And also, even in the euphoria of victory, Travis and other senior staff at Bletchley Park would have been aware of the need to maintain security in the face of a new, chilly, geopolitical reality.
The collective image we now seem to carry of VE Day is of jubilant crowds in the streets of London, men and women with arms linked, people hanging on to lampposts, the nighttime streets bathed in lights after the years of blackouts; people getting “lit up” themselves, as the singer Hutch put it, getting uproariously drunk, dancing, and kissing that perfect night away.
And, despite the restrictions, nothing could stop the celebrations in Bletchley either. When the day came, one veteran recalls: “We assembled on the grass outside the Mansion to hear that war with Germany was over. There was a huge cheer and great excitement—though our delight was muted as we still had the Japanese to finish before we could go home. So back to our decoding machines.”
There was another reason for going back to the machines. Even since the beginning of the war, it had not just been German traffic that was the target for the codebreakers; it was Russian traffic too. And in Bletchley—as well as in the wider intelligence and military hierarchy—all thoughts were now starting to focus on “the next war”: that was, the possibility of having to face a dominant Russia with plans of its own for European territorial gains.
Recall that as far back as the early 1920s, the British had been doing their best to monitor all Soviet secret traffic. Come 1939, there was no less reason to do so, especially in the face of the Molotov-Ribbentrop Pact that foreswore any acts of aggression between Russia and Germany. So at the time of the Russian invasion of Finland in 1940, with the enormous amount of encrypted messages that were generated therewith, Bletchley managed to get a hook into the Russian codes. When the Germans invaded France, the Polish codebreakers who had been living in exile in Paris were forced to flee once more, to Britain. And from the outstation at Stanmore in Middlesex, these Poles were able to intercept and read Russian traffic emanating from the Ukraine.
When in 1941 Germany invaded Russia, the mighty bear appeared suddenly to be an ally of the British. It was officially put about that she was treated as such, and that Churchill especially ordered that any intelligence operations against Russia should desist. This was not entirely the case.
In September 1944, Sir Stewart Menzies, head of MI6, held discussions involving Sir Edward Travis, Gordon Welchman, and Colonel Tiltman. These talks were about the urgent need to keep pace with (and, if possible, ahead of) Soviet encryption technology. Some personnel in Hut 3, including an American officer, were instructed to focus on the Red Army’s most advanced equipment. And come VE Day, it was clear that even after the Japanese had been vanquished, a core of codebreakers would remain with the institution of Bletchley Park, even if they did not stay within the grounds of the Park itself.
Of course, like every other aspect of the war effort, the fact of VE Day in May 1945 didn’t instantly mean that everyone could be released from their duties. As Jean Valentine recalls: “When the war in Europe stopped, my mother wrote to me in Ceylon and said, ‘Isn’t it wonderful that war’s over, when are you coming home?’ My mother didn’t see any reason why I couldn’t come back immediately. I said, ‘Mum, excuse me, it’s still going on here.’”
But it was not just the fact that the war in the east was still rumbling on. Even in Europe, demobilization was a complex business. Troops were not returned home instantly. And for the majority of the denizens of Bletchley Park, release from the work was slow. In the period between May and September of 1945, there were fresh tasks to address. Rather than decrypts, there was now the business of sweeping up after the destruction.
“Technical books came in in their dozens from Germany,” says Sheila Lawn of that time. “And they had me and a few other girls just sitting and making details of the books so that they could be traced. The author and the way it was published and what the subject was.”
Her husband-to-be, Oliver, was engaged in similar mopping up. “I was writing reports detailing what we had done. And we both left in September.”
“It was a sort of dribble down,” says Sheila. “The numbers got less. Ten thousand, then eight thousand, however many it was, we didn’t all leave at once.”
There is a curious poignancy about the annual report of the Bletchley Park Recreation Club at the end of 1945. In the previous year, the club had proudly boasted of “play-readings,” “operatic performances,” even a musical concert given by the Bletchley Park choir on the BBC, as well as “fencing, chess, badminton, and squash.” Now, though, the activities were fading as the young people began to move away. The floor of the hall no longer vibrated to the thump of couples ballroom dancing; there were fewer to take part in the specially organized cycling and hiking clubs. Even the “swing music enthusiasts,” as the Park’s annual report referred to these daring souls, were dwindling in number. Bravely the club went on, meaning to carry on with all these impeccably middle-class activities until the very end.
In June 1945, there was a curious echo of Gordon Welchman’s initial observation about codebreakers’ aptitude for music. The BBC was already aware of the rich gathering of talented musicians at the Park, and had featured some of them in a previous broadcast. Now, startlingly, it was decided that there should be a broadcast from the Park itself. In one sense, it looked like surprisingly lax security—but then, of course, Bletchley’s talented actors had been touring the local county, with their audiences aware of where they worked if not of what they did. So why not the BBC? Among the pieces performed were works by Ralph Vaughan Williams—a composer who, in his harking back to Tallis and to English folk melodies, reinforced a certain national sense of age-old coherence. The audience for the program was not told what else the musicians had been achieving in recent years.
By that time, with Europe now silent, coming to terms with the devastation, grim news was still reaching Bletchley Park from across the world. In August 1945, intelligence was received that atom bombs had been dropped on the Japanese cities of Hiroshima and Nagasaki. Rosemary Calder told Michael Smith of what it was like when the messages started coming in. “I was on a day watch by myself,” she said. “I didn’t know the bomb had been dropped but you could tell from the disruption of all the messages that something terrible had happened. You could just feel the people standing there, screaming their heads off.”3
But it was finally over. A copy of a rather stiff memo on the subject of “Re-Distribution of Surplus Staff” survives. Intended as a generic letter to all staff members, it begins:
Owing to the cessation of hostilities, there is no further work for you to do in this organization. In these circumstances, there is no object in continuing to report here for duty, and with effect from…[blank space left for date], you are free to absent yourself. You must, however, present yourself, with this letter, to the Staff Officer, Hut 9, before your departure, to give certain particulars for his records.…
In accordance with Treasury regulations, your name has been forwarded to the Treasury for consideration for employment in other Government Departments.4
This transition was by no means instant, nor was it painless. With personnel leaving, those left behind were juggling new and awkward shift systems to keep up with the remaining work. The Bletchley Park directorate made some proposals concerning weekend leave, which one might imagine would have been welcomed after all those years of seven-day shifts. Curiously, these met with fierce resistance: what worked in peacetime for “family and friends,” as one Park staffer put it, was not right for this organization. At Bletchley, the shifts worked best when the staff could “choose” which days off they wanted. And what, this staffer added, would be the benefit of having every Sunday off?
“Shopping is impossible on Sundays anywhere,” said the staffer in a memo of protest. “So no shopping would be possible one week in three (according to the BP shift system). In London, shopping is only possible in the forenoon of Saturdays. Those making appointments—hairdressing, dentistry, interviews for jobs—would be severely handicapped.”
Perhaps even more persuasively, added the staffer, “Entertainment facilities are rare on Sundays and overcrowded on Saturdays. Difficulties would be greatly increased if all BP personnel were free at weekends.” And possibly the clincher? “Billeted personnel are in many cases obliged to be ‘out’ for the midday meal. They are doubly unwelcome on Sundays, when the billetor is himself at home, and on Sunday, it is more difficult than on weekdays to get a meal elsewhere.”5
John Herivel took a slightly more emollient line in the debate over compulsory weekends off, though he felt that in his own department, he and his colleague Macintosh should carry on as before. “If we were to confine our leave to Saturdays and Sundays,” he wrote in another memo still held in the archives, “there would be some days when neither of us were on. This could be very inconvenient.”6
Nevertheless, the slow, careful dismantling of the operation was under way. And the image of Bletchley Park in the later months of 1945 seems to be one of once-teeming blocks now lying empty, of sparse huts, and of many of the rooms in the house itself now starting to echo. “It was so strange,” said one veteran. “It was already nearly empty—a ghost town with just a few removal men shifting furniture. Thousands of people just walked out of the gate never to return.”
Actually the clear-up was a shade more complex than that: given the intense secrecy and security, every square inch of the house, and all the huts, and all the blocks, had to be combed and sifted for any hint of coding material or even machine components to ensure that absolutely nothing had been left behind.
The operation was largely packed up: some (though by no means all) bombes were dismantled. Some Wrens were gleeful about these acts of destruction, for they had come almost to hate the machines. Now, instead of having to treat them with the utmost care, they let parts drop and fall and roll on the floor, and they shouted with enthusiasm.
Meanwhile, bonfires of paperwork were made in the grounds of Bletchley Park. The huts, the house, all areas had to be combed for any bits of paper that might have got away. Some decrypts were found jammed into the gap of a window frame; the huts had been so draughty in winter that they were used to muffle the cold.
The Colossus and Heath Robinson machines were also taken to pieces. Anything that remained was kept either at Stanmore or Eastcote in Middlesex. The bombe machines that remained at Eastcote, however, did not stop, for they now had other sorts of traffic and signals intelligence to decode.
For most of those who had worked at the Park though, the conflict was over; and many of those young people now had a shattered country to rebuild. One is tempted to look back across the years and see idealism in that enthusiasm; but it might be more accurate to say that this was a time for unflinching realism, and even a certain sense of apprehension.