In the early hours of 6 June 1944, D-Day, Garbo made repeated attempts to warn his Abwehr controller that the Allied forces were on their way. This move was agreed by Allied commanders on the basis that it would be too late for the Germans to do anything about it but would ensure that they still believed in Garbo as their best-informed secret agent after the invasion had begun. As predicted it only served to increase their trust in him and paved the way for the next stage of the deception. Shortly after midnight on 9 June, as the Allied advance faltered and with the elite 1st SS Panzer division on its way from the Pas de Calais, together with another armoured division, to reinforce the German defences in Normandy, Garbo sent his most important message about the D-Day landings. Three of his agents were reporting troops massed across East Anglia and Kent and large numbers of troop and tank transporters waiting in the eastern ports.
After personal consultation on 8 June in London with my agents Donny, Dick and Derrick, whose reports I sent today, I am of the opinion, in view of the strong troop concentrations in south-east and east England, that these operations are a diversionary manoeuvre designed to draw off enemy reserves in order to make an attack at another place. In view of the continued air attacks on the concentration area mentioned, which is a strategically favourable position for this, it may very probably take place in the Pas de Calais area.
Garbo’s warning went straight to Hitler who ordered the two divisions back to the Pas de Calais to defend against what he expected to be the main invasion thrust and awarded Pujol the Iron Cross. Had the two divisions continued to Normandy, the Allies might well have been thrown back into the sea. On 11 June, Bletchley Park decyphered a message from Berlin to Garbo’s controller in Madrid saying that Garbo’s reports ‘have been confirmed almost without exception and are to be described as especially valuable. The main line of investigation in future is to be the enemy group of forces in south-eastern and eastern England.’ Only the messages decyphered from the Abwehr Enigma could have provided Allied commanders with that sort of high-level reassurance that the deception was working.
The importance of the Abwehr Enigma and the Jellyfish link in confirming the D-Day deception cannot be overstated. One of Telford Taylor’s Special Branch intelligence officers, Don Bussey, said:
Ultra made a tremendous contribution to the success of the deception planning for the Normandy landing because we were able to follow through Ultra not only what the German forces were doing but also that Fortitude was working so well. The Germans still believed well into July that Patton had an Army in south-eastern England that was going to come across to Pas de Calais so they couldn’t send reinforcements to Normandy. This is a very important aspect of how Ultra contributed to strategic consideration. That’s big stuff and not to be minimised.
Brigadier Bill Williams, who was Montgomery’s intelligence officer during the invasion of Europe, said that no army ever went to war better informed about the enemy.
Intelligence officers at BP were briefed before D-Day and thereafter we made it our business in Normandy to send a daily ISUM [Intelligence Summary] from 21 Army Group saying what we thought was happening in front of us and in general attempting in a friendly and unofficial fashion to keep the Park aware of what we were trying to do. The whole series of signals was conversational. One felt one was talking to friends and from that feeling of gratitude which we hoped was reflected in the casually worded terms sent to the Park emerged at least from the point of view of one consumer, a belief that because of them he was getting a better service. The people at the other end knew what he wanted and there seemed to be no hesitation in the answer. G (R), the staff branch responsible for deception and cover plans, was more dependent on Ultra than any of the rest of us. It was the only source revealing the enemy’s reaction to a cover plan. Without Ultra we should never have known. In the case of Fortitude South (the Pas de Calais cover plan) it is arguable that without Ultra confirmation that it was selling, it might have been dropped.
Senior administrators at Bletchley Park were very well aware that some of the young men working there wondered whether they shouldn’t be fighting alongside their friends and relatives, who were now thrust into the thick of battle. Eric Jones, the head of Hut 3, the military and air intelligence reporting section, told his staff that the work they were doing might not be so dangerous but it was just as important to the war effort. One recent report sent out by Hut 3 had shown that enemy dispositions in the Cotentin peninsula in Normandy had changed. US paratroopers from the 82nd Airborne had been due to drop in the area around La Haye du Puits on the west of the Cotentin peninsula, but a Bletchley decrypt showed in late May that several German divisions had moved into the area and that any landing there would have had disastrous consequences. The resultant change to 82nd Airborne’s dropping zone had saved the lives of up to 15,000 men, Jones said.
At this moment, in far the biggest combined operation in history, the first of the airborne troops are down. Sailors and airmen are facing frightful dangers to transport the first ground troops across the Channel and protect them on their way; more sailors and airmen are daring everything to blast holes in the German defences; and the ground troops themselves, in their thousands, will soon be literally throwing away their lives in the main assault by deliberately drawing enemy fire so that others may gain a foothold; and we are in complete, or almost complete, safety; some of us are even enjoying something akin to peacetime comfort. It’s a thought we cannot avoid and it’s a thought that inevitably aggravates an ever-present urge to be doing something more active; to be nearer the battle, sharing at least some of its discomforts and dangers. Such feelings cannot be obliterated, but they can be subjugated to a grim resolve to serve those men to the very utmost of our capacity. There is no back-stage organisation (and I think of Hut 3, Hut 6, Sixta and the Fish Party as an indissoluble whole) that has done more for past Allied operations and Allied plans for this assault; and none that can contribute more to the development of the invasion once the bloody battles for the beaches have been won.
Amid concern at the damage the U-Boats might inflict on the invasion forces, Frank Birch had arranged for a number of Royal Navy radio intercept positions to be set up in Bletchley Park. All signals indicating danger to the invasion force were dispatched from the Hut 4 ‘Z’ Watch on what was known as a ‘Rush’ basis and the OIC was normally able to pass them on to the naval escorts within thirty minutes of the Germans sending them. Birch’s initiative was the first and only time that any messages were actually intercepted at Bletchley Park.
‘This step was taken with some hesitation in view of the risk associated in having GC&CS associated with masts and aerials,’ said Harry Hinsley.
But it was fully justified by the exceptional speed with which the Naval Enigma was decrypted during the crucial days in which the assault forces were crossing the Channel and getting ashore. We were able to watch the expedition going across as well as getting the first German response. We quickly realised they weren’t expecting invasion and as soon as the assault waves were ashore we started reading all the emergency messages from the German navy and sending them straight on to the invasion force leaders in their command ships off the beaches. Throughout the assault phase the average time-lag between the interception of the German signals and the delivery of the decrypts to the OIC was to be thirty minutes during those large parts of each day in which the Enigma keys were being decrypted currently.
Within forty-eight hours of the initial landings, the first of twenty-eight British and American Special Liaison Units set up to pass the Ultra intelligence on to the Allied commanders were reporting through their Special Communications Units that their positions were secure and they were ready to receive and pass on the reports from Bletchley.
‘Shortly after the Normandy landings, I was assigned to the European theatre to be one of the field representatives handling the Ultra information with the US military command, both air force and Army,’ said Don Bussey.
All
US commands had these Ultra representatives who would ensure the security of this information and that it was handled in the proper way. I had a Special Communications Unit manned by British officers, both Army and RAF, that supported me, and they were the ones who would receive the messages over the air from Bletchley Park. It’s very important to realise that day in, day out, the most important thing that Ultra had to tell us was the complete German order of battle. We would know their divisions by number. We would know where they were. We would know their subordinations by corps and army and by army group. We’d know the boundaries between division and between other units, and all this gave us the kind of information which is absolutely indispensable. I would process all this information and pass it on to the people at headquarters who were authorised to receive it.
The mobile Y Service units were already producing large amounts of information about the German reaction. In conjunction with Bletchley Park, they produced the position of one of the most important German headquarters, allowing the British to mount a series of air strikes that put paid to a counter-attack which would have driven a gap between the American and British armies.
‘One of the very first things that was noticeable was that there was a radio station very busy indeed in Normandy, near the front,’ said Ralph Bennett, one of the Hut 3 intelligence reporters.
Now Y service could locate this place exactly and could monitor the number of signals coming in and out; it was obviously a very important headquarters. But on 10 June, Enigma revealed that it was the headquarters of Panzergruppe West, the headquarters of all the tanks in the invasion area. Monty knocked it out for three weeks and lots of the senior staff officers were killed.
There were gaps in the information provided by Ultra. The codebreakers were unable to provide a precise location for 32nd Panzer Division, which was defending the vital British objective of Caen and held up Montgomery’s advance for more than a month. They had also missed the presence of a German infantry division defending Omaha beach. But these were the only blank spaces in an otherwise complete and detailed picture of the German order of battle.
Although the Red Enigma remained a constant source of intelligence until July 1944, when the Germans realised it was compromised, Army Enigma circuits began to be broken and as the Allied invasion wore on Army Enigma networks became more important than their Luftwaffe counterparts. There was a major potential problem when von Rundstedt’s Fish link to Berlin became temporarily unreadable.
‘Until D-Day, they changed the wheel patterns once a month,’ said Art Levenson.
So once you had them recovered, you were in. But after we invaded, they changed the patterns every day, so the job became much more difficult. We went to the boss Edward Travis and said: ‘We need four more Colossi because they’re changing the patterns too often.’ He went to Churchill who said: ‘Anything they want.’ So we got the four new Colossi and they were absolutely necessary. We used them to recover the links, which we never would have done without them.
On 20 July, a group of senior Army officers, among them Colonel Claus von Stauffenberg, attempted to assassinate Hitler. Stauffenberg took a bomb, hidden in a briefcase, to a staff conference at the Rastenberg Führer HQ and placed it under the table. As soon as he heard the explosion and unaware that Hitler had escaped serious injury, he left for Berlin to tell the generals planning the military takeover that the Führer was dead.
Alex Dakin said one of his most vivid memories from Bletchley was being on duty in the Hut 4 ‘Z’ Watch ‘when not much was happening’. The messages coming into the Watch in the wire tray by which messages were passed from Hut 8 ‘were nothing exciting – but then in the next almost empty tray, one of the most exciting messages ever.’
The message read: OKM AN ALLE EINSATZ WALKUERE NUR DURCH OFFIZIER ZU ENTZIFFERN OFFIZIER DORA DER FUEHRER ADOLF HITLER IST TOT DER NEUE FUEHRER IST FELDMARSCHALL VON WITZLEBEN…
‘Naval Headquarters to all. Operation Valkyrie. Officer only to decypher. Officer setting Dora [D]. The Führer Adolf Hitler is dead. The new Führer is Field Marshal von Witzleben.’
Sadly, Hitler wasn’t dead. By 11 o’clock that night, the attempted military coup was over and von Stauffenberg and a number of other senior officers had been executed.
As the Allied forces poured into Normandy, they had been held back by heavy German resistance, orchestrated by Field Marshal Günther von Kluge. But at the beginning of August, the American 12th Army Group under General Omar Bradley swept south though Avranches turning west into Brittany and eastwards behind the German tanks.
‘I remember after the invasion there was a long period of time when Montgomery’s forces and the US forces under General Bradley were being built up,’ said Selmer Norland, one of the Americans working in Hut 3.
Units were being ferried across the Channel and, after they captured the initial bridgeheads, they were sort of pinned down for quite a long period of time while this build-up was taking place. And I remember a particular night when I was working on a message and some German unit reported that the American tank spearheads were in the outskirts of Rennes. I told the Army adviser who was on duty at the time and we dashed for a map to find out where Rennes was. We were astonished to find that it was almost all the way across the Brittany peninsula.
Convinced of his own infallibility as a military strategist, Hitler now decided that von Kluge should force his way through to the western Normandy coast at Avranches, cutting the American thrust in half. ‘We must strike like lightning,’ he told his chiefs of staff.
When we reach the sea the American spearheads will be cut off. We might even be able to cut off their entire beachhead. We must not get bogged down in cutting off the Americans who have broken through. Their turn will come later. We must wheel north like lightning and turn the entire enemy front from the rear.
There was certainly an element of reason in the idea but with more than a million Allied troops now firmly established in Normandy, von Kluge had little hope of carrying it out and, far worse, with Montgomery’s 21st Army Group pressing down on him from the north and the Americans sweeping westwards along his southern flank, he risked becoming trapped in an Allied pincer movement.
The Allies, fully informed by Bletchley Park of the German plans, ensured the initiative failed. As von Kluge’s counterattack faltered with its only route of retreat through a small gap south of the town of Falaise, Hitler insisted that it should be carried through to the bitter end. ‘On its success depends the fate of the Battle of France,’ Hitler said in a message sent in the early hours of 10 August and decyphered in Hut 6 almost immediately. ‘Objective of the attack, the sea at Avranches, to which a bold and unhesitating thrust through is to be made.’
John Prestwich was on duty in Hut 3 when Hitler’s orders came through the hatch from Hut 6.
I remember it. My goodness I remember it. I remember we queried it at the time. We said: ‘It cannot be true.’ It seemed to us inconceivable. But what made sense was that the Americans had broken out of their base in the Cotentin peninsula and the Germans had made what was a perfectly sensible limited spoiling attack on the American lines of communication. Then there came through this detailed order that four or five German armoured divisions were to go hell for leather for Avranches and this opened up the whole possibility of wiping out the cream of the German armed forces. All you had to do was to close the Falaise Gap and there was this great pocket. But it was an order from Hitler. The German generals might have thought it was lunatic, and Rommel clearly did on at least one occasion, but they obeyed on the spot because they were under oath.
Within a few days, it was clear that von Kluge had no hope of carrying out Hitler’s orders and, fearing that at any moment the Allies would surround his forces, he ordered the withdrawal. Susan Wenham was one of the codebreakers on duty in Hut 6 on duty on 16 August when von Kluge’s orders came through.
It was the most exciting night I had. The Germans were making plans to make their last terrific pu
sh to try to get out of the pincer they were in. I was on the night shift and the day shift had had an enormous message. They came in sections; they weren’t allowed to do them more than a certain length. It was a ten-part message and only six of the parts of the message, the Teile, came through. They had managed to break those during the day and the message was to say how the Germans were planning to get out of this impasse. Then during the night, a very obvious re-encodement of this came in, all ten of the parts, and we could see by looking at it that it was a word-for-word re-encodement, which was absolutely not allowed. So we let Hut 3 know and we got all the Bombes cleared. We worked like mad on this thing during the night and by morning it was all put through and finished. So that was a very exciting night.
Allied timidity allowed 300,000 German soldiers to escape from the Falaise Pocket, but a further 250,000 were either killed or captured. With the Germans now in full retreat, the Allies poured out of Normandy towards the the Belgian and German borders. Paris was liberated on 25 August as Montgomery’s 21st Army Group raced towards Belgium, heading for the Ruhr and, with the newspaper headlines trumpeting ‘Berlin by Christmas’, an unwarranted level of over-confidence set in.
The Secrets of Station X Page 27