THE SECRET WAR

Otago Daily Times, Issue 27018, 1 March 1949, Page 5

THE SECRET WAR

Triumphs of British Science

By Winston S. Churchill

During the human struggle between the British and German Air Forces, between pilot and pilot, between A A batteries and aircraft, between ruthless bombing and the fortitude of the British people, another conflict was going on step by step, month by month. This was a secret war, whose battles were lost or won unknown to the public, and only with difficulty comprehended, even now, by those outside the small high scientific circles concerned. Unless British science had proved superior to German, and unless its strange, sinister resources had been effectively brought to bear on the struggle for survival, we might well have been defeated, and, being defeated, destroyed. A wit' wrote ten years ago, “ The leaders of thought have reached the horizons of human reason; but all the wires are down, and they can only communicate with us by unintelligible signals.” Yet upon the discerning of these signals, and upon the taking of right and timely action on the impressions received depended our national fate and much else, I knew nothing about science, but I knew something of scientists, and had had much practice as a Minister in handling things I did not understand. I had, at- any rate, an acute military perception of what would help and of what would hur . of what would cure and of what would kill. My four years’ work upon the Aid Defence Research Committee had made me familiar with the outlines of radar problems. I therefore immersed myself so far as my faculties allowed in this Wizard War, and strove to make sure that all that counted came without obstruction or neglect at least to the threshold of action. There were no doubt greater scientists than Frederick Lindemann, though his credentials and genius command respect. But he had two qualifications of vital consequence to me. First, as these pages have shown, he was my trusted friend and confidant of twenty years. Together we had watched the advance and onset, ot world disaster. Together we had done our best to sound the alarm. And now we were in it, and I had the power to guide and arm our effort. How could I have the knowledge? Here came the second of his qualities. Lindemann could decipher the signals from the experts on the far horizons and explain to me in lucid, homely terms what the issues were. There are only twenty-fqjir hours in the day, of which at least seven must be spent in sleep and three in eating or relaxation. Anyone in my position would have been ruined if he had attempted to dive into depths which not even a lifetime of study could plumb. What I had to grasp were the practical results, and just as Lindemann gave me his view for all it was worth in this field, so I made sure by turning on my power-relay that some at least of these terrible and incomprehensible truths emerged in executive decisions. * * * Progress in every branch of radar was constant and unceasing during 1939, but even so the Battle of Britain, from July to September, 1940. was, as I have described, fought mainly by eye and ear. I comforted myself at first in these months with the hope that the fogs and mist and cloud which accompany the British winter and shroud the island with a mantle would at least give a great measure of protection against accurate bombing by day and still more in darkness. Deafeating the Bombers For some time the German bombers had navigated largely by radio beacons. Scores of these were planted like lighthouses in various parts of the Continent; each with its own call-sign, and the Germans, using ordinary directional wireless, could fix their position by the angles from which any two of theses transmissions came. To counter this we soon installed a number of stations which we called “Meacons.” These picked up the German signals, amplified them, and sent them out again from somewhere in England. The result was that the Germans, trying to home on their beams, were often led astray, and a number of hostile aircraft were lost in this manner, Certainly one German bomber landed voluntarily in Devonshire thinking it was France.

split beams from two stations could be arranged to cross over any town in the Midlands or Southern England. The German airman had only to fly along one beam until he detected the second, and then to drop his bombs. Q.E.D.! Nazi Pilots Misled This was the principle of the splitbeam and the celebrated “ Knickebein ” apparatus, upon which Goering founded his hopes, and the Luftwaffe were taught to believe that the bombing of, English cities could be maintained in spite of cloud, fog and darkness, and with all rhe immunity, alike frqm guns and intercepting fighters, which these gave to the attacker. With their logical minds and .deliberate largescale planning, the German High Air Command staked their fortune in this sphere on a device which, like the magnetic mine, they thought would do us in. Therefore they did not trouble to train the ordinary bomber pilots, as ours had been trained, in the difficult art of navigation. The German pilots followed the beam as the German people followed the Fuhrer. They had nothing else to follow. But', duly forewarned, and acting on the instant, the simple British had the answer. B> erecting the proper stations in good time in our own country we could jam the beam. This \yould of course have been immediately realised by the enemy. There was another and superior alternative. We could put a repeating device in such a position that it strengthened the signal from half of the split beam and not from the other. Thus the hostile pilot, trying to fly so that the signals from both halves of the split beam were equal, would be deflected form the true course. The cataract of bombs which would have shattered, or at least tormented a city would fall fifteen or twenty miles away in an open field. About August 23, the first new Knickebein stations, near Dieppe -■ and Cherbourg, were trained on Birmingham, and a large-scale' night offensive began. We had of-; course our “ teething troubles ” to . get through; but within a few days the Knickebein beams were deflected or jammed, and for the, next two months, the critical months of September and October,' the German bombers wandered _ around England bombing by guess- *’ work, or else being actually ledi astray. One instance happened to come to my notice. An officer in my Defence office sent his wife and children to the country during the London raids. Ten miles away from any town they were much astonished to see a series of enormous explosions occurring three fields away. They counted over a hundred heavy bombs. They wondered what’ the Germans could be aiming at, and thanked God they were spared. The officer mentioned the incident the next day, but so closely was the secret kept, so narrow was the circle, so highly specialised the information, that no satisfactory explanation could be given to him, even in his intimate position. The very few who knew exchanged celestial grins. The Germans, after internal conflicts, at last revised their methods. It happened, fortunately for them, that one of their formations. Kampf Gruppe 100, was using a special beam of its own. It called its equipment the “X apparatus,” a name of mystery which, when we came across it. threw up an intriguing challenge to our Intelligence. By the middle of September we had found out enough about it to design counter measures, but this particular jamming equipment could not be produced for a further two months. In consequence Kampf Gruppe 100 could still bomb with accuracy. The enemy hastily formed a pathfinder group from it, which they used to raise fires in the target area by incendiary bombs, and these became a guide for the rest of the Knickebeined Luftwaffe. Battle of Wits Coventry, on November 14-15 was the first target attacked by the new method. Although our new jamming had now started, a technical error prevented it from becoming effective for another few montths. Even so our knowledge of the beams was helpful. From the settings of the hostile beams and the times at which they played we could forecast the target and the time route and height of attack. Our night fighters had, alas at this date neither the numbers nor the equipment to make much use of the information: It was nevertheless invaluable to our fire-figthing and other civil defence services. These could often be concentrated in the threatened area and special warnings given to the populiation before the attack started. Presently our counter-measures improved and caught up with the attack. Meanwhile decoy fires, code-named “ Starfish,” on a very large scale were lighted by us with the right timing in suitable open places to lead the main attack astray, and these sometimes achieved remarkable results. By the beginning of 1941. we had mastered the “X apparatus”: but the Germans were also thinking hard, and about this time they brought in a new aid called “Y apparatus.” Whereas the two earlier systems had both used cross beams over the target, the new system used only one beam, together with a special method of range-finding by radio, by which the aircraft could be told how far it was along the beam. When it reached the correct distance it dropped its bombs. By good fortune and the genius and devotion of all concerned, we had divined the exact method of working the “ Y apparatus ” some months before the Germans were able to use it in operations, and by the time they were ready to make it their pathfinder we had the power to render it useless. On the verv first night when the Germans committed themselves to the “ Y apparatus ” our new counter-measures came into action against them. The success of our efforts was manifest from the acrimonious remarks heard passing between the pathfinding aircraft and their ■ controlling ground stations by our listening instruments. The faith of the enemy air ctrews in their new- ~ device was thus shattered at the . outset, and after many failures the method was abandoned. The bomb- . ing of Dublin on the night of May;.-30-31, 1941 may well have been an j unforeseen and unintended result of our interference with “Y.” By itself beam-distortion was not enough. Once having hit the correct target, it was easy for the German bombers, unless they were confused by our “ Starfish ” decoy fires, to return again to the glow of the fires they lit the night before. Somehow they must be clawed down. For this we developed two new devices, rockets and aerial mines. Bv fitting our AA batteries with radar it was possible to predict the position of an enmey aircraft accurately enough, provided it continued to fly in a straight line at the same speed: but this is hardly what experienced pilots do. Of course they zigzagged or “ weaved,” and this meant that in the twenty or thirty seconds between firing the gun and the explosion of the shell they might well be half a mile or so from the predicted point. : Use of Rockets A wide yet intense burst of fire round the predicted point was an answer. Combinations of a hundred guns would have been excellent, if the guns could have been , produced and the batteries manned and all put in the right place at the right time. This was beyond human power to achieve. But a very simple, cheap alternative was available in the rqcket. or. as it had been called for secrecy, the Unrotated Projectile (UP). The 3-inch rocket carried a much more powerful warhead than a 3-inch shell. It was not so accurate. On the other hand rocket projectors had the inestimable advantage that they could be made very auickly and easily in enormous numbers without burdening our hard*; driven gun factories. Thousands of these UP projectors were made, and some millions of rounds of ammunition,'

However, in June [1940] I received a painful shock. Professor Lindemann reported to me that he believed tire Germans were preparing a device by means of which they would be able to bomb by day or night whatever the weather. It now appeared that the Germans had developed a radio beam which, like an invisible searchlight, would guide the bombers with considerable precision to their target. The beacon beckoned to the pilot, the beam pointed to the target. Lindemann told me also that there was a way of bending the beam if we acted at once, but that I must see some of the scientists, particularly the Deputy Director of Intelligence Research at the Air Ministry, Dr R V Jones, a former pupil of his at Oxford. Accordingly, with anxious mind I convened on June 21 a special meeting in the cabinet room, at which about fifteen persons were present, including Sir Henry Tizard and various air force commanders. A few minutes late, a youngish man—who, as I afterwards learnt, had thought his sudden summons to the cabinet room must be a pratical joke—hurried in and took his seat at the bottom of the table. According to plan, I invited him to open the discussion. For some months, he told us, hints had been coming from all sorts of sources on the Continent that the Germans had some novel mode of nightbombing on which they placed great hopes. In some way it seemed to be linked with the code-word Knickebein (curtsey), which our Intelligence had several times mentioned without being able to explain. At first it had been thought that the enemy had got agents to plant beacons in our cities on which their bombers could home; but this idea had proved untenable. Some weeks before two or three curious squat towers had been photographed in odd positions near the hostile coast. They did not seem the right shape for any known form of radio or radar. Nor were they in places which could be explained on any such hypothesis. Recently a German bomber had been shot down with apparatus which seemed more elaborate than was required for night-landing by the Lorenz beam, which appeared to be the only known use for which it might be intended. For this and various other reasons, which he wove together into a cumulative argument, it looked as if the Germans might be planning to navigate and bomb on some sort of system of beams. A few days before under cross-examination on these lines a German pilot had broken down and admitted that he had heard that something of the sort was in the wind. Such was the gist of Mr Jones’s tale. For twenty minutes or more he spoke in quiet tones, unrolling his chain of circumstantial evidence, the like of which for its convincing fascination was never surpassed by tales of Sherlock Holmes or Monsieur Le Coq. I will now explain in the kind of terms which I personally can understand how the German beam worked and how we twisted it. Like the searchlight beam, the radio beam cannot be made very sharp; it tends to spread: but if what is called the “split beam" method is used considerable accuracy can be obtained. Let us imagine two searchlight-beams parallel to one another, both flickering in such a way that the left-hand beam comes on exactly when the right-hand beam goes out, and vice versa. If an attacking aircraft was exactly in the centre between the two beams, the pilot’s course would be continuously illuminated; but if it got say, a little bit to the right, nearer the centre of the righthand beam, this would become the stronger and the pilot would observe the flickering light, which was no guide. By keeping in the position where he avoided the flickerings he would be flying exactly down the middle, where the light from both beams is equal. And this middle path would guide him to the target. Two

Shells or rockets alike are of course only effective if they reach the right spot and explode at the right moment. Efforts were therefore made to produce aeriel mines suspended on long wires floating down on parachutes which could be laid in the path of the enemy air squadrons. It was impossible to pack these into shells. But a rocket, with much thinner walls, has more room. The advantage of such mine-fields over shell-fire is of course that they remain lethal for anything up to a minute. For wherever the wing hits the wire it pulls up the mine until it reaches the aircraft and explodes. There is thus no need .for exact fusesetting, as with ordinary shells.

Aerial mines could of course be placed in position by rockets laid by aircraft, or simply raised on small balloons. The last method was ardently supported by the Admiralty. In fact, however, the rockets were never brought into action on any considerable scale. By the time they were manufactured in large numbers mass attacks by bombers had ceased. Nevertheless it was surprising and fortunate that the Germans did not develop this counter to our mass-bombing raids' in the last three years of the war.

There was another important aspect. In 1940 the dive-bomber seemed to be a deadly threat to our ships and key factories. One might think that aircraft diving on a ship would be easy to shoot down, as the gunner can aim straight at them without making allowance for their motion. But an aeroplane end on is a very small target, and a contact fuse will work only in the rare event of a direct hit. To set a time fuse so that the shell explodes at the exact moment when it is passing the aircraft is almost impossible. An error in timing of onetenth of a second causes a miss of many hundreds of feet. It therefore seemed worth while to try to make a fuse which would detonate automatically when the projectile passed near the target, whether it actually hit or not.

As there is little space in the head of a shell the roomier head of the 3-inch rocket was attractive. While I was still at the Admiralty in 1940 we pressed this idea. Photo-electric (PE) cells were used which produced an electrical impulse whenever there was a change of light, such as the shade of the enemy plane. By February, 1940, we had a’ model which I took to the Cabinet, and showed my colleagues after one of our meetings. When a matchbox was thrown past the fuse it winked perceptibly with its demonstration lamp. The cluster of Ministers who gathered round, including the Prime Minister, were powerfully impressed. But there is a long road between a grimacing model and an armed mass-produced robot. We worked hard at the production of the socalled PE fuses, but here again by the time they were ready in any quantity our danger and their hour had for the moment passed. Attempts were made in 1941 to design a similar proximity fuse, using a tiny radar set arranged to explode the war-head when the projectile passed near the aircraft. Successful preliminary experiments were made, but before this fuse was developed in England the Americans, to whom we imparted our knowledge, actually succeeded not only in prelecting the instrument, but in reducing its size so much that the whole thing could be put into the head not merely of a rocket but of a shell. These so called “ Promimity Fuses,” made in the United States, were used in great numbers in the last year of the war, and proved potent against the small unmanned aircraft (VI) with which we were assailed in. 1944, and also in the Pacific against Japanese aircraft. [Copyright 1949 in USA by the New York Times Company and Time (Inc.) (publisher of Time and Life); in the British Empire by the Daily Telegraph, Ltd.; elsewhere by International Co-operation Press Service (Inc.). World rights reserved. Reproduction in full or in part in any language strictly prohibited.] The destroyers-bases deal with the United States is detailed to-morrow by Mr Churchill.