4
A Hidden Conflict — Lindemann’s Services — Progress of Radar — The German Beam — Mr. Jones’s Tale — Principle of the Split Beam or “Knickebein” — Twisting the Beam — Goering’s Purblind Obstinacy — The X-Apparatus — Coventry, November 14/15 — The Decoy Fires — The Y-Apparatus Forestalled — Frustration of the Luftwaffe — Triumph of British Science — Our Further Plans — The Rocket Batteries — General Pile’s Command and the Air Defences of Great Britain — The Aerial Mine Curtains — The Proximity Fuze — The Prospect of Counter-Attack — The Expansion of “Air Defence Great Britain.”
DURING THE HUMAN STRUGGLE between the British and German Air Forces, between pilot and pilot, between anti-aircraft 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, to those outside the small high scientific circles concerned. No such warfare had ever been waged by mortal men. The terms in which it could be recorded or talked about were unintelligible to ordinary folk. Yet if we had not mastered its profound meaning and used its mysteries even while we saw them only in the glimpse, all the efforts, all the prowess of the fighting airmen, all the bravery and sacrifices of the people, would have been in vain. 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 what would hurt, of what would cure and of what would kill. My four years’ work upon the Air 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 of 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-four hours in the day, of which at least seven must be spent in sleep and three in eating and 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.
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 these 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.
However, in June I received a painful shock. Professor Lindemann reported to me that he believed the 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. They might not hit a particular factory, but they could certainly hit a city or town. No longer, therefore, had we only to fear the moonlight nights, in which at any rate our fighters could see as well as the enemy, but we must even expect the heaviest attacks to be delivered in cloud and fog.
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 practical 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 night-bombing 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 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 Lecoq. As I listened, the Ingoldsby Legends jingled in my mind:
But now one Mr. Jones
Comes forth and depones
That, fifteen years since, he had heard certain
groans
On his way to Stone Henge (to examine the stones
Described in a work of the late Sir John
Soane’s)
That he’d followed the moans,
And, led by their tones,
Found a Raven a-picking a Drummer-boy’s bones!
When Mr. Jones had finished, there was a general air of incredulity. One high authority asked why the Germans should use a beam, assuming that such a thing was possible, when they had at their disposal all the ordinary facilities of navigation. Above twenty thousand feet the stars were nearly always visible. All our own pilots were laboriously trained in navigation, and it was thought they found their way about and to their targets very well. Others round the table appeared concerned.
* * * * *
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 one to 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 right-hand 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 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.!
This was the principle of the split beam 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 the immunity, alike from guns and intercepting fighters, which these gave to the attacker. With their logical minds and deliberate large-scale planning, the German High Air Command staked their fortunes 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. A far simpler and surer method, lending itself to drill and large numbers, producing results wholesale by irresistible science, attracted alike their minds and their nature. The German pilots followed the beam as the German people followed the Fuehrer. They had nothing else to follow.
But, duly forewarned, and acting on the instant, the simple British had the answer. By erecting the proper stations in good time in our own country we could jam the beam. This would, of course, have been almost 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 one 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 from 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. Being master, and not having to argue too much, once I was convinced about the principles of this queer and deadly game, I gave all the necessary orders that very day in June for the existence of the beam to be assumed, and for all counter-measures to receive absolute priority. The slightest reluctance or deviation in carrying out this policy was to be reported to me. With so much going on, I did not trouble the Cabinet, or even the Chiefs of the Staff. If I had encountered any serious obstruction, I should of course have appealed and told a long story to these friendly tribunals. This, however, was not necessary, as in this limited and at that time almost occult circle obedience was forthcoming with alacrity, and on the fringes all obstructions could be swept away.
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 guesswork, or else being actually led astray.
One instance happened to come to my notice. An officer in my Defence Office sent his wife and two young 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 German air crews soon suspected that their beams were being mauled. There is a story that during these two months nobody had the courage to tell Goering that his beams were twisted or jammed. In his ignorance he pledged himself that this was impossible. Special lectures and warnings were delivered to the German Air Force, assuring them that the beam was infallible, and that anyone who cast doubt on it would be at once thrown out. We suffered, as has been described, heavily under the Blitz, and almost anyone could hit London anyhow. Of course, there would in any case have been much inaccuracy, but the whole German system of bombing was so much disturbed by our counter-measures, added to the normal percentage of error, that not more than one-fifth of their bombs fell within the target areas. We must regard this as the equivalent of a considerable victory, because even the fifth part of the German bombing, which we got, was quite enough for our comfort and occupation.
* * * * *
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 the guide for the rest of the de-Knickebeined Luftwaffe.
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 months. 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-fighting and other Civil Defence services. These could often be concentrated in the threatened area and special warnings given to the population 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 the “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 very 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 crews in their new device was thus shattered at the outset, and after many failures the method was abandoned. The bombing of Dublin on the night of May 30/31, 1941, may well have been an unforeseen and unintended result of our interference with “Y.”
General Martini, the German chief in this sphere, has since the war admitted that he had not realised soon enough that the “high-frequency war” had begun, and that he underrated the British Intelligence and counter-measures organisation. Our exploitation of the strategic errors which he made in the Battle of the Beams diverted enormous numbers of bombs from our cities during a period when all other means of defence either had failed or were still in their childhood. These were, however, rapidly improving under the pressure of potentially mortal attack. Since the beginning of the war we had brought into active production a form of air-borne radar called “A.I.,” on which the Air Defence Research Committee had fruitfully laboured from 1938 onward, and with which it was hoped to detect and close on enemy bombers. This apparatus was too large and too complicated for a pilot to operate himself. It was, therefore, installed in two-seater Blenheims, and later in Beaufighters, in which the observer operated the radar, and directed his pilot until the enemy aircraft became visible and could be fired on – usually at night about a hundred yards away. I had called this device in its early days “the Smeller,” and longed for its arrival in action. This was inevitably a slow process. However, it began. A widespread method of ground-control interception grew up and came into use. The British pilots, with their terrible eight-gun batteries, in which cannon-guns were soon to play their part, began to close – no longer by chance but by system – upon the almost defenceless German bombers.
The enemy’s use of the beams now became a positive advantage to us. They gave clear warning of the time and direction of the attacks, and enabled the night-fighter squadrons in the areas affected and all their apparatus to come into action at full force and in good time, and all the anti-aircraft batteries concerned to be fully manned and directed by their own intricate science, of which more later. During March and April the steadily rising rate of loss of German bombers had become a cause of serious concern to the German war chiefs. The “erasing” of British cities had not been found so easy as Hitler had imagined. It was with relief that the German Air Force received their orders in May to break off the night attacks on Great Britain and to prepare for action in another theatre.
Thus, the three main attempts to conquer Britain after the fall of France were successively defeated or prevented. The first was the decisive defeat of the German Air Force in the Battle of Britain during July, August, and September. Instead of destroying the British Air Force and the stations and air factories on which it relied for its life and future, the enemy themselves, in spite of their preponderance in numbers, sustained losses which they could not bear. Our second victory followed from our first. The German failure to gain command of the air prevented the cross-Channel invasion. The prowess of our fighter pilots, and the excellence of the organisation which sustained them, had in fact rendered the same service – under conditions indescribably different – as Drake and his brave little ships and hardy mariners had done three hundred and fifty years before, when, after the Spanish Armada was broken and dispersed, the Duke of Parma’s powerful army waited helplessly in the Low Countries for the means of crossing the Narrow Seas.
The third ordeal was the indiscriminate night-bombing of our cities in mass attacks. This was overcome and broken by the continued devotion and skill of our fighter pilots, and by the fortitude and endurance of the mass of the people, and notably the Londoners, who, together with the civil organisations which upheld them, bore the brunt. But these noble efforts in the high air and in the flaming streets would have been in vain if British science and British brains had not played the ever-memorable and decisive part which this chapter records.
* * * * *
There is a useful German saying, “The trees do not grow up to the sky.” Nevertheless, we had every reason to expect that the air attack on Britain would continue in an indefinite crescendo. Until Hitler actually invaded Russia we had no right to suppose it would die away and stop. We therefore strove with might and main to improve the measures and devices by which we had hitherto survived and to find new ones. The highest priority was assigned to all forms of radar study and application. Scientists and technicians were engaged and organised on a very large scale. Labour and material were made available to the fullest extent. Other methods of striking down the hostile bomber were sought tirelessly, and for many months to come these efforts were spurred by repeated, costly, and bloody raids upon our ports and cities. I will mention three developments, constantly referred to in the Appendices to this Volume, in which, at Lindemann’s prompting and in the light of what we had studied together on the Air Defence Research Committee of pre-war years, I took special interest and used my authority. These were, first, the massed discharge of rockets, as a reinforcement of our anti-aircraft batteries; secondly, the laying of aerial mine curtains in the path of a raiding force by means of bombs with long wires descending by parachutes; thirdly, the search for fuzes so sensitive that they did not need to hit their target, but would be set off by merely passing near an aircraft. Of these three methods on which we toiled with large expenditure of our resources, some brief account must now be given.
None of these methods could come to fruition in 1940. At least a year stood between us and practical relief. By the time we were ready to go into action with our new apparatus and methods, the enemy attack they were designed to meet came suddenly to an end, and for nearly three years we enjoyed almost complete immunity from it. Critics have therefore been disposed to underrate the value of these efforts, which could only be proved by major trial, and in any case in no way obstructed other developments in the same sphere.
* * * * *
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 had lit the night before. Somehow they must be clawed down. For this we developed two new devices, rockets and aerial mines. By fitting our antiaircraft batteries with radar, it was possible to predict the position of an enemy 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.
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 rocket, or, as it had been called for secrecy, the Unrotated Projectile (U.P.). Even before the war Dr. Crow, in the days of the Air Defence Research Committee, had developed two-inch and three-inch rockets which could reach almost as high as our anti-aircraft guns. The three-inch rocket carried a much more powerful warhead than a three-inch shell. It was not so accurate. On the other hand, rocket projectors had the inestimable advantage that they could be made very quickly and easily in enormous numbers without burdening our hard-driven gun factories. Thousands of these U.P. projectors were made, and some millions of rounds of ammunition. General Sir Frederick Pile, an officer of great distinction, who was in command of our anti-aircraft ground defences throughout the war, and who was singularly free from the distaste for novel devices so often found in professional soldiers, welcomed this accession to his strength. He formed these weapons into huge batteries of ninety-six projectors each, manned largely by the Home Guard, which could produce a concentrated volume of fire far beyond the power of anti-aircraft artillery.
I worked in increasing intimacy throughout the war with General Pile, and always found him ingenious and serviceable in the highest degree. He was at his best not only in these days of expansion, when his command rose to a peak of over three hundred thousand men and women and twenty-four hundred guns, apart from the rockets, but also in the period which followed after the air attack on Britain had been beaten off. Here was a time when his task was to liberate the largest possible numbers of men from static defence by batteries, and, without diminishing the potential fire-power, to substitute the largest proportion of women and Home Guard for regulars and technicians. But this is a story which must be told in its proper place.
The task of General Pile’s command was not merely helped by the work of our scientists; as the battle developed, their aid was the foundation on which all stood. In the daylight attacks of the Battle of Britain, the guns had accounted for two hundred and ninety-six enemy aircraft, and probably destroyed or damaged seventy-four more. But the night raids gave them new problems which, with their existing equipment of only searchlights and sound locators, could not be surmounted. In four months from October 1 only about seventy aircraft were destroyed. Radar came to the rescue. The first of these sets for directing gunfire was used in October, and Mr. Bevin and I spent most of the night watching them. The searchlight beams were not fitted till December. However, much training and experience were needed in their use, and many modifications and refinements in the sets themselves were found necessary. Great efforts were made in all this wide field, and the spring of 1941 brought a full reward.
During the attacks on London in the first two weeks of May – the last of the German offensive – over seventy aircraft were destroyed, or more than the four winter months had yielded. Of course, in the meanwhile the number of guns had grown. In December there had been 1450 heavy guns and 650 light; in May there were 1687 heavy guns, 790 light, with about 40 rocket batteries.1 But the great increase in the effectiveness of our gun defences was due in its origin to the new inventions and technical improvements which the scientists put into the soldiers’ hands, and of which the soldiers made such good use.
* * * * *
By the middle of 1941, when at last the rocket batteries began to come into service in substantial numbers, air attack had much diminished, so that they had few chances of proving themselves. But when they did come into action, the number of rounds needed to bring down an aircraft was little more than that required by the enormously more costly and scanty anti-aircraft guns, of which we were so short. The rockets were good in themselves, and also an addition to our other means of defence.
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 aerial 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. A certain amount of three-inch rocket ammunition, which could lay an aerial minefield on wires seven hundred feet long at heights up to twenty thousand feet, was made and held ready for use against mass attacks on London. The advantage of such minefields 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 fuze-setting, 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. Even a few minelaying aircraft would have been able to lay and maintain a minefield over any German city, which would have taken a toll of our bombers the more deadly as numbers grew.
* * * * *
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 fuze will work only in the rare event of a direct hit. To set a time fuze so that the shell explodes at the exact moment when it is passing the aircraft is almost impossible. An error in timing of one-tenth of a second causes a miss of many hundreds of feet. It therefore seemed worth while to try to make a fuze which would detonate automatically when the projectile passed near to the target, whether it actually hit it or not.
As there is little space in the head of a shell, the roomier head of the three-inch rocket was attractive. While I was still at the Admiralty in 1940 we pressed this idea. Photo-electric (P.E.) 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 fuze, 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-production robot. We worked hard at the production of the so-called P.E. fuzes, 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 fuze, using a tiny radar set arranged to explode the warhead when the projectile passed near the aircraft. Successful preliminary experiments were made, but before this fuze was developed in England, the Americans, to whom we imparted our knowledge, actually succeeded not only in perfecting 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 “Proximity Fuzes,” 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 (V-1) with which we were assailed in 1944, and also in the Pacific against Japanese aircraft.
* * * * *
The final phase of “The Wizard War” was, of course, the radar developments and inventions required for our counter-attack upon Germany. These suggested themselves to some extent from our own experiences and defensive efforts. The part they played will be described in future volumes. In September, 1940, we had nearly nine long months ahead of us of heavy battering and suffering before the tide was to turn. It may be claimed that while struggling, not without success, against the perils of the hour, we bent our thoughts steadily upon the future when better times might come.
AIR DEFENCE GREAT BRITAIN
