Most Secret War

by R. V. Jones

  The particular object of this paper is to indicate the weapons to be used against England. The mine campaign has failed: the failure has been due in part to our effective reaction, and in part, perhaps, to a shortage of mines. The Norwegian campaign certainly risked the sacrifice of the entire German surface Navy. In the alleged timetable of Nazi expansion, there was to have been an interval of several years between the subjugation of Northern France and the conquest of England; perhaps in the interval a fleet was to have been built. If Germany is expecting a swift conclusion to the war with England, it therefore follows that her campaign now depends entirely on heavy attack by air. It is beyond the scope of this paper to comment upon either the feasibility or the wisdom of attempted invasion, but there is perhaps something in the view that actual invasion is not imminent, but after a swift and heavy attack from the air, using all the weapons at his command, Hitler will then offer seductively moderate terms. This line of attack is largely dependent on the subjection of France, and probably represents the worst contingency we have to face. We might then find a force of four or five thousand aircraft of mixed types ready to attack us.

  Following the same theme the report concluded:

  In conclusion, some relief may be derived from the fact that despite rumours to the contrary, there are some responsible quarters in Germany which are preparing for a long war. It is a fact that the German War Department has advertised (10th April 1940) for an ersatz electrical accumulator, to be constructed almost entirely from materials found within the Reich. A prize of RM. 10.000 is offered, and the competition closes on 1st January 1941: clearly the German War Department expects still to be at war on that date.

  What I said was not altogether popular at the time (23rd May 1940), because 1941 seemed an age away, and it was not easy to see how we were going to survive. But, as it turned out, the only point where I was wrong was that I thought that the bombing might come first and the peace offer later, whereas Hitler played things the other way round. At the same time, I did crystallize my warning about the beams:

  It is possible that they have developed a system of intersecting radio beams so that they can locate a target such as London sufficiently accurately for indiscriminate bombing. No information is available regarding the wavelength to be employed, but the accuracy of location expected by the Germans is something like ½ mile over London from the western frontier of Germany. Efforts are still being made to determine the probable wavelengths so that counter measures can be employed.

  No doubt owing to the illegibility of my writing, Daisy Mowat had actually typed ‘metre’ instead of ‘mile’ in the second sentence, but even this did not create undue interest, and I still found myself with hardly enough to do. On 10th May Anthony Eden announced the formation of the Local Defence Volunteers, and before he had finished the broadcast I had telephoned Richmond police station to join. I attended the first few parades, with an enormous personal superiority, for no one else had any weapons, and I had six pistols and a rifle. But the records of the L.D.V. show that on 13th August 1940, long before it became the Home Guard, I was given a discharge, ostensibly on the grounds that my services ‘were no Longer Required’, this being a curious euphemism for the fact that they were by then more urgently required elsewhere.

  Winston began to make his speeches, and started to rally the country. We had heard L. S. Amery’s ringing repetition of Cromwell’s words a few days before in Parliament, ‘You have sat too long here for any good you have been doing. Depart, I say, and let us have done with you. In the name of God, go!’ And a new spirit was beginning to inspire the country. Winston made his ‘Blood, tears, toil, and sweat’ speech on 13th May, and we grimly prepared for the worst.

  Around 20th May I well remember Fred Winterbotham’s Deputy, John Perkins, coming into my office and going up to the map on my wall and saying, ‘This is the situation. The Germans are here and here and here and our Army is cut off and retreating to the sea at Dunkirk. The Chiefs of Staff think that we shall be lucky if we get twenty thousand out.’ The position seemed hopeless and yet by the end of the month we had recovered three hundred thousand.

  The country was fired by the epic of the small boats that had sailed, some as many as seven times, into the teeth of the Luftwaffe to bring back our Army; and among those who took their boats to Dunkirk was my cousin Reg Mytton. I heard of the Commander-in-Chief, Lord Gort, standing on the beach with two Guardsmen as loaders while he tried to shoot down German dive bombers with a rifle. He also told one of his staff officers, Captain George Gordon Lennox, that however few of the Army could be evacuated, priority was to be given to the R.A.F. pilots who had parachuted from aircraft shot down over the beach head, for they would be vital to the final fight for Britain. And whereas most other regiments had straggled back, the Grenadiers had sent an R.S.M. to Dover to pick up any Grenadiers and drill them, exhausted as they were, to march off the quay in formation as though it were Horseguards. The Navy were so indignant at witnessing this Spartan treatment that the R.S.M. was the object of many Able-Bodied cat-calls, but tradition had been preserved.

  The trains from the Channel ports passed through Herne Hill, and my parents’ home was in sight of the station. Vera and I spent the afternoon of Saturday 25th May with them, watching the trains packed with dishevelled troops on their way to Victoria, where my colleague Freddie Wintle recounted the scene: Times may change in other respects, but the Guards never do. I was at Victoria Station when the army remnants started arriving back from Dunkirk. There were a good many trainloads of them. I was deeply shocked with the appearance of the first lot.

  About the third trainload turned out to be a couple of companies of Foot Guards. What a contrast! They were glorious to see. They fell in on the platform, dressed, and marched out at attention, not even looking at the girls in the crowd of onlookers. Every Guardsman had his full equipment and his rifle. Everything was polished and properly adjusted. Thank God, I thought, that ass Hore-Belisha can never undermine the Guards. The sight of them was like a tonic—with a very large gin in it—which I promptly had in their honour.

  CHAPTER ELEVEN

  The Crooked Leg

  AFTER THE drama of Dunkirk the next few days were surprisingly quiet. Early in June the Tizard Committee met in Oxford, and I was asked to attend. The Committee had to face the prospect that Lindemann, whom it had earlier rejected, was now Scientific Adviser to the Prime Minister. But the one memory that I have of the meeting is of Sholto Douglas, then the Deputy Chief of Air Staff, asking, ‘Can anyone tell me what the Germans are up to? For the past few days Manston [the R.A.F. aerodrome near Dover] has been packed full of our aircraft flown back from France and presenting an ideal target—and yet no German aircraft has attacked!’ It all confirmed my impression that the Germans had been surprised by their own success, and now had no coherent plan for the immediate future.

  We experienced some sporadic night raids in the first few days of June and, in view of our later failures, our nightfighters shot down a misleadingly large proportion of the attackers. I still had not enough to do, and so decided to spend the day of 11th June at the Admiralty Research Laboratory, to see what my former colleagues were doing. During the day I received two telephone calls, one from Group Captain Blandy, the Head of the R.A.F. ‘Y’ Service (which intercepted German radio signals), and the other from Lindemann. Each asked when I would be back in London; and when I said that I expected to spend all day at Teddington but would return if they wished, the answer in each case was that tomorrow would do.

  On the morning of 12th June, therefore, I went to see Blandy; and as I sat down he slowly pulled open a drawer of his desk and produced a scrap of paper and handed it to me saying, ‘Does this mean anything to you? It doesn’t seem to mean much to anybody here.’ On the paper I read:

  ‘KNICKEBEIN, KLEVE, 1ST AUF PUNKT 53 GRAD 24 MINUTEN NORD UNDEIN GRAD WEST EINGERICHTET’.

  There, once again, was ‘Knickebein’; and ‘Kleve’ could be the west German tow
n that we knew as Cleves, where Anne came from. If so the translation would run: ‘Cleves Knickebein is confirmed (or established) at position 53° 24’ north and 1° west.’ The geographical position referred to was a point in England, roughly on the Great North Road a mile or so south of Retford. I immediately told Blandy that it meant everything to me, and that it suggested that the Germans had a radio beam transmitter called Knickebein set up at Cleves, on the nearest German soil to England, and that the existence of the beam had been confirmed one way or another at this position over England. I quickly recognized that it was a decoded message, because I knew that during the preceding two months Bletchley had begun to be successful in decoding some of the Enigma messages. This particular one had been sent by the Chief Signals Officer of Flieger Korps IV at 1455 hours on 5th June, and had been decoded four days later. By this time a stream of decodes was coming from Bletchley into Winterbotham’s office; somehow this one had been missed but had then been spotted by an air-minded cryptographer, very probably Josh of the Interrogation Panel, and sent up to Blandy. I told the latter how the message had confirmed my previous thoughts and how I proposed to follow it up.

  I then went across to the Cabinet Offices to see Lindemann for only the second time in the whole war; and had I gone to see him first instead of Blandy the course of the next few days, and perhaps the winter of 1940, might have gone quite differently. He told me that he had sent for me because he would like to hear what I knew about German radar. I told him that I was convinced that it existed, and mentioned details from the Oslo Report and also the fact that L. H. Bainbridge-Bell, whom the Admiralty had sent out to survey the wreck of the Graf Spee, had reported that she had radar-type aerials. The later information, which should have been quite conclusive, seemed somehow to be ignored in Whitehall, which for many months more continued to debate whether the Germans had radar. As a final point I told Lindemann that I had just received the Knickebein message, and that I was convinced that the Germans had an intersecting beam system for bombing England; and if they could make narrow beams for navigation they could also make narrow beams for radar. Lindemann immediately said that the beams would not work for radionavigation, because they would have to use short waves which would not bend round the curvature of the earth. Armed with Eckersley’s computations, I told him that, contrary to what he supposed, they would. I then returned to my office to take stock of the situation.

  While I had been at Teddington, a party from the Air Staff headed by Group Captain D. L. Blackford, an enthusiastic and friendly officer then in the Plans Directorate but later in charge of Air Force Security, had rushed up to Retford on the theory that Knickebein might be a system operated by fifth columnists, in the hope of catching them redhanded. The party had found nothing, as I would have expected.

  I investigated the bombers available to Flieger Korps IV, and found that these were Heinkels 111’s of Kampf Geschwadern 4 and 27. Therefore whatever equipment was used for receiving the Knickebein beam must be capable of being fitted to this type of aircraft. I immediately telephoned Denys Felkin because I knew that he now had prisoners from the bombers shot down during the preceding few nights, and briefed him about the information that I needed.

  He duly interrogated the prisoners without at first getting anything of value. But when the prisoners were alone one of them said to another that no matter how hard we looked we would never find the equipment. This could not have been a better challenge because it implied that the equipment was in fact under our noses, but that we would not recognize it. I therefore obtained a copy of the full technical examination of the Heinkel 111 that had been shot down in the Firth of Forth raid, and looked especially at the various items of radio equipment. The only item that could possibly fill the bill was the receiver that was carried in the aircraft for the purpose of blind landing. It was labelled as E. Bl. 1 (which stood for Empfänger Blind 1—blind landing receiver type 1) and was ostensibly for the normal purpose of blind landing on the Lorenz beam system, which was by now standard at many aerodromes. I ascertained that the radio equipment had been evaluated by N. Cox Walker at Farnborough and so I telephoned him. ‘Tell me, is there anything unusual about the blind landing receiver?’ I asked. ‘No’, he replied—and then, ‘But now you mention it, it is much more sensitive than they would ever need for blind landing.’ So that was it. I now knew the receiver, and the frequencies to which it could be tuned, and therefore on which the Knickebein beam must operate.

  I had argued myself through all these steps by the morning of the following day, 13th June. I went again to see Lindemann, taking with me this time a copy of Eckersley’s computed map, which persuaded him to withdraw his objection of the previous day. Eckersley himself attended a meeting in Blandy’s office and, unknown to me, he was given a copy of the vital Enigma message to consider. Lindemann now prepared a note for Churchill, which started, ‘There seems some reason to suppose that the Germans have some type of radio device with which they hope to find their targets.’ Churchill initialled the note and sent it to Archie Sinclair, who was now Minister of Air, adding, ‘This seems most intriguing and I hope you will have it thoroughly examined.’1

  The next day, Felkin told me that he had a fresh prisoner who said that Knickebein was indeed a bomb-dropping device; it involved two intersecting radio beams and it had been developed at Rechlin. As Felkin spoke, I mentally leapt at the prospect of putting in a false crossbeam to make the Germans drop their bombs before they reached the target.

  The prisoner professed to be anti-war, and drew a sketch of what he thought was one of the transmitting towers which he had seen at Rechlin. This was square in cross-section and had sides which sloped somewhat together towards the top, rather like a magnified version of the bottom quarter of Cleopatra’s Needle. I had through the winter been collecting information about any unusual towers that had been seen in Germany, and the prisoner’s drawing agreed exactly, although on a larger scale, with a tower that had been photographed near an airfield at Hörnum on Sylt, where we knew that there was a Lorenz beacon.

  On the same day, 14th June, Sinclair appointed Air Marshal Sir Philip Joubert, whose official post at that time was Adviser for Combined Operations, to take charge of the Air Ministry work on the beams.

  On 15th June Joubert held a meeting in his office in the afternoon, at which both Lindemann and I were present, and where it was considered that the evidence was now sufficiently strong to show that immediate action was needed. Joubert therefore called a meeting of the Night Interception Committee for the afternoon of the following day, a Sunday. What a change from my inactivity of only a week ago ! During the morning Scott-Farnie and I went out to see Felkin to pick up the most recent items of information from the prisoners, and we arrived back just in time for the meeting. I there encountered for the first time the Commander-in-Chief of Fighter Command, Air Chief Marshal Sir Hugh Dowding. After I had given my evidence Joubert turned to Dowding and said, ‘Well, C-in-C, what should we do?’ Dowding answered in one word: ‘Jam!’ But although he answered so positively, his note to Tizard, written after the meeting, was less positive: ‘The meeting was called to discuss some rather nebulous evidence about German long-distance navigation by Lorenz beam. Various plans were made to find out what the Germans were doing, and these may or may not be effective.’1

  But, typical of any occasion on which Joubert was in the Chair, the meeting came to some crisp decisions. Air Commodore Nutting, the Director of Signals, should proceed with the formation of a flight of aircraft fitted with equipment to try to find the beams. Watson-Watt and I should investigate the possibility of putting listening receivers on our radar towers, where the high siting should give us a good chance of hearing the beams. Group Captain Blandy should evolve a jamming system and should co-ordinate all reports and recommendations. Group Captain Blackford should continue to search for concealed instruments that might be operated by fifth columnists, and Joubert himself should co-ordinate all investigations and should prepare a r
eport every Friday for the Prime Minister. Professor Lindemann was to take up the question of designing new receivers, capable of detecting radio waves down to wavelengths of 40 centimetres.

  So far, Tizard had not come into the picture at all, beyond noting earlier2 from what I had told him about the X-Gerät in February and March that ‘The Germans obviously have something in the way of R.D.F. (radar) and have ideas of using it for bombing at night’. It happened that he was out of London for most of the week, and only returned on the morning of Monday 17th June. To bring him up to date, it was arranged that I should meet him at 9.15 a.m. in the office of Air Commodore Nutting, the Director of Signals. I told him of what I had found in the preceding few days, and felt that he was not altogether enthusiastic. This was a little surprising in that I was in a sense his own protégé, and I think that he must for once have reacted much as Lindemann would almost certainly have done had it been Tizard to whom I had told the story first. Lindemann would almost inevitably have tried to think of reasons for doubting, and this is what Tizard himself now seemed to do. In a note written that day he said, ‘I may be wrong, but there seemed to me to be unnecessary excitement about this latest alleged German method for dealing with the country. One cannot possibly get accurate bombing on a selected target in this way. It would, of course, be perfectly simple to use this system to bomb a place like London under completely blind conditions, but if we on our part had the task of bombing Berlin under blind conditions we could do it without this system. I feel that the use of the system is far more dangerous if it is looked at from the point of view of being able to concentrate large numbers of aircraft round a particular district in bad weather conditions by day. That is what we must be prepared for and it is on that occasion and that only that I should jam.’ In view of the subsequently discovered inaccuracy of our bombing, and of my previously expressed doubts arising from our pre-war navigational accidents, Tizard’s faith in our blind bombing ability was, in retrospect, surprising.