The inspection of a V1, which had landed in Sweden after a test flight, debris from early attacks on London and finally the overrunning of launch sites near Cherbourg after D-Day had given the Allies considerable information about this new weapon. By the time the main V1 offensive ended on 5 September 1944, eighty-three per cent had been destroyed by gunfire as they flew over southern England. Indeed, on 28 August, defences destroyed ninety out of ninety-seven flying bombs, only four reaching London. As the Allies advanced, many V1 sites were evacuated and new depots set up in places such as Nucourt, St Leu and Rilly-la-Montagne, all in northern France, which were discovered through Bletchley Park decrypts. But the Germans had changed to a new method – launching V1 missiles from aircraft. Enigma decrypts in July 1944 referred to the Luftwaffe Third Bomber Wing, III/KG (Kampf Geschwader) 3 (later I/KG53), and it was not until the end of the month that the real purpose of this group of Heinkel 111s was realised. The air offensive of V1s on England ended on 13 January 1945, after 4,261 had been destroyed by fighters, anti-aircraft attack and barrage balloons. But, from October 1944 until the end of March 1945, V1 attacks were carried out against Antwerp, Liège and Brussels. Indeed, there were more attacks on Antwerp than London.
The Japanese Naval Attaché’s enciphered messages had revealed more information about the V2 and then Bletchley Park had a major breakthrough when a special Enigma key, known as Corncrake, was first intercepted in June 1944 and revealed messages being sent between Peenemünde and Blizna. These decrypts were the first to reveal to the Allies the name of Wernher von Braun who, post-war, was to be a major figure in the American space programme. There were three special cipher keys for the V-weapons: Corncrake, Ibis and Jeboa, which operated between March 1944 and the end of the war. Jeboa was a Luftwaffe key and handled V1 attacks, the other two were Army keys and dealt with the V2, Corncrake handling experimental and preparatory information, while Ibis covered the actual operations. Although these were special V-weapon keys, other keys also provided information on these weapons, such as the Luftwaffe key Brown, which had provided information on the beams directing bombers to their targets during the Battle of Britain as well as other keys.
Corncrake only lasted from the middle of May 1944 until the end of July. It was discovered after a long message was brought into Hut 6’s Army Research – which at the time also housed the Army cryptographers – for a routine examination, as was standard procedure for new and obscure groups. The initial break of 13 May is described in the Official History of Hut 6:
The contents of Corncrake created an intelligence sensation in Hut 3 [Army-Air Intelligence]: the exact significance of much of it was obscure but clearly referred to scientific artillery experiments of importance … Strong representations were made from the highest quarters in the Park in favour of a determined drive to break more days and the work was at once set under foot.
Corncrake’s W/T system comprised three stations – Heidelager (which acted as Control), Peenemünde and Koeslin – and practically all the traffic was to and from Heidelager. Corncrake suddenly ended with the evacuation of Heidelager on 23 July 1944, and no traffic was passed after this date. On Ibis, with one exception, all the breaks occurred in the six weeks from 12 February to 24 March 1945. In fact, Ibis traffic was passed in small quantities back in October 1944 – the rocket attacks had commenced the previous month – and it was not until November that its separate identity was revealed. Ibis passed traffic not only on Enigma, but quite large quantities in other ciphers, and the Enigma messages could be identified by the non-Enigma traffic which, it was discovered, was concerned with the launch of rockets, as the messages coincided with the times of V2 launches. The V2 launch batteries in Holland were in a habit of sending evening messages to their Group Control containing a list of the rocket launches. Bletchley Park dubbed these messages ‘Rocket Bradshaws’, all providing times of rocket departures from Holland. The times of arrival in England – four minutes later – were not given. Ibis traffic, which reached its peak at the beginning of February 1945 with eighty messages a day, fell to a trickle in March and vanished altogether in the last week of that month. The American Enigma-breaking bombes had done sterling work on Ibis, and it was perhaps fitting that the last V-key to be broken was on VE-Day, 8 May 1945.
Jerboa, the V1 key, gave Bletchley Park twenty days of breaks in a period of less than three weeks from 13 August to 2 September 1944. This key came to the attention of the codebreakers in July 1944 and was known from its three-letter traffic, known as Klavier, which was connected with the launching of flying bombs. In early September 1944, Jerboa disappeared in consequence of the Allied advance through Belgium and France. In December 1944 and later February-March 1945, there was a resurrection of Jerboa, which reached its peak in the week ending 24 February, with a daily average of fifty-one messages. The following week this fell to fifteen and finally disappeared for ever. In July 1944, Professor Jones had concluded that figures contained in Enigma messages were production numbers and that there were around 1,000 rockets available. By now the view of the Crossbow committee was that the V2, manufactured by Mittelwerk, comprised liquid fuel rocket engines, supersonic aerodynamics, gyroscopic guidance and rudders in jet control. In all, 5,200 V2s were built, and they could be fired from a simple site or mobile platforms, and did not require a complex launching mechanism. Such was the concern at the highest levels of government of a combined V1-V2 attack, that contingency measures included the evacuation of two million people and of factories and hospitals from London as well as providing protected buildings for government officials who would have to remain in the capital. On 14 July, a decrypt had revealed a message from Blizna to Peenemünde, referring to the supply of fifty one-ton ‘Elephants’, which turned out to be the codename for warheads. However, Britain’s boffins were still struggling with the weight of the V2 and its exact components, with the weight being assessed at between eleven and fourteen tons, fuelled by a mixture of liquid oxygen and alcohol and some compound including alcohol and with a range of between 120 and 200 miles, depending on the size of the warhead, calculated at between one and two tons. It was also believed to take between about four and six minutes to travel either 150 or 200 miles. Then a hint that the V2 offensive was imminent was discovered in a decrypt from the Japanese Ambassador in Vienna in August, quoting German Foreign Minister Joachim von Ribbentrop as the source. Moreover, there were considerable problems locating the V2 sites, causing considerable anxiety among the top brass. In the hunt for information on the V2, an Enigma message gave a vital clue when it revealed that someone from Blizna was interested in a crater 160 miles away, a distance that was beyond the range of the flying bomb. As Professor Jones recalled, ‘This single fact made us think that we were once again on the trail of the rocket.’
On 8 September 1944 the first V2 attack on London took place, fired from Holland and landing at 1843 in Chiswick, followed another sixteen seconds later by one falling at Epping. The Last V2 was to fall on England at 1645 on 27 March 1945 at Orpington, Kent. At Peenemünde, the first successful launch of a V2 – after two failures – was on 3 October 1942. Although an awesome weapon of destruction, for the boffins who had been working on the project, many for ten years, it was a moment to savour. According to General Dornberger, for the first time a machine of human construction, a 5.5 ton missile, covered a distance of 120 miles with a lateral deflection of only 2.5 miles from the target. They had become the first to have given a rocket built on the principles of aircraft construction a speed of 3,300 mph by means of the jet drive peculiar to rocket.
We have thus proved that it is quite possible to build missiles or aircraft to fly at supersonic speed, given the right form and suitable propulsion. Our self-steering rocket has reached heights never touched by any man-made machine.
There was little defence against these attacks except the bombing of V2 operational sites. In addition, the Double X system – turned German agents sending back false information to their Abwehr (military intelligence) handlers under the control of MI5 – were misleading the Germans about the accuracy of the rockets, persuading them to fire the missiles short of their targets. Bletchley Park was also playing its part, as much of the intelligence was obtained from Corncrake which, temporarily suspended at the end of July when Blizna was evacuated, resumed on 16 August. It first threw light on the V2 organisation on 19 and 21 September, when Bletchley Park decrypted signals between 14 and 16 September. This revealed site visits by SS General Hans Kammler, a civil engineer who took over from Dornberger and became Special Commissioner of the V-weapons programme in August 1944 when it came under SS control. Kammler had designed the extermination camps, including gas chambers and crematoria. He had also been involved in various other secret weapon projects. He is believed to have committed suicide in May 1945, although his body was never found. The decrypts also revealed that V2 trials had been transferred to a new site at Tuchel, north of Bromberg (Bydgoszcz) in Poland. Low grade cipher traffic about the V2 was also read by Allied intercept units in Belgium.
The intelligence gathered on the V-weapons was a classic use of every means of obtaining top secret information. Not least was the heroism of the underground resistance forces, especially in France and Poland, many of whom were captured, tortured and gave their lives to obtain vital information, the use of ‘turned’ agents to send back disinformation to their German handlers, photo reconnaissance flights and codebreaking. The V1 created havoc and 10,000 were fired at England, 2,419 reaching London, 3,857 were shot down before reaching their target, thirty landed on Southampton and Portsmouth, and one on Manchester, killing a total of 6,184 people and injuring 17,981. The grim statistics of the V2 rocket tell their own story. An estimated 2,511 civilians were killed in London with 5,869 seriously injured, and 213 were killed and 598 injured elsewhere. The V2 statistics from 8 September 1944 to 27 March 1945 are that 1,054 fell on England (about five a day), 517 (less than three a day) hit London and more than 2,700 Londoners were killed. As to the value of the V-keys, The Official History of Hut 6, looking to the post-war world, commented that the ultimate significance of the V-keys ‘lay in their long-term connection with the probable future of developments of science as applied to war’. The German boffins had come close to finding a decisive weapon, but as General Dornberger commented, only one thing can be said with absolute certainty, that the use of the V2 could be aptly summed up in two words: ‘too late’. He complained that lack of foresight in high places and failure to understand the technical background were to blame. Nevertheless, what had been created was new and unique and could never be erased from the annals of technology. He remarked:
We tackled one of mankind’s greatest tasks regardless of circumstances and found a first practical solution; we opened the gate and pointed the way to the future.
That comment, written at the end of the war, has proved to be accurate. Modern warfare is all about scientific and technological weaponry. Today’s armies – and the civil space programmes – can trace their origin to Nazi Germany and the terror weapons.