Shortly after 10 o'clock on the evening of 21st June 1940, an Anson of the Blind Approach Training and Development Unit took off from Wyton, in Huntingdonshire. In the fuselage was a wireless set of a type used by the American police. It was specially designed to receive frequencies in the neighbourhood of 30 megacycles per second.
The pilot, who had rejoined the unit the previous day, was a little vague about the object of the exercise. He was clear enough, however, about his immediate orders, which were to attempt to find a bean signal on frequencies of 30, 31.5 or 33 mcs. Though the weather was murky below, the aircraft was soon clear of the clouds, and at 10,000 feet, under the starry canopy of the midsummer night sky, the search began. It was not long before the wireless operator—a peacetime radio enthusiast who continued to twiddle his knobs with the chevrons of a Royal Air Force corporal on his sleeve—picked up very loud and clear signals on 30 mcs. They consisted of dashes repeated sixty times minute—as in the British standard beam-approaching and the German Lorenz system for blind landing.
This was promising, and the pilot headed north with high hopes. About twenty miles beyond Wyton the dashes changed into a continuous note. The aircraft was in the beam. It proved to be less than half a mile wide, with very clearly defined dot and dash edges; and by keeping towards one edge the pilot found that he could fly along it with an accuracy of 100–200 yards. Having confirmed his position from a 'fix' the navigator then plotted the path of the beam. In one direction it extended towards Western Germany, whence in fact it was originating; and in the other, doubtless for reasons not unconnected with the presence of the Rolls-Royce aero-engine works, it passed across the town of Derby.
When the pilot landed he telephoned the news of his success to Fighter Command. Thence it was passed to the Air Ministry, where it was received with great satisfaction by Dr. R. V. Jones, a youthful
and extremely versatile physicist who was in charge of Scientific Intelligence. Working on the evidence of agents, captured German aircrews and other sources, Jones had concluded that the Germans possessed a radio beam system capable of being used for 'blind' bombing over England, and that the receiving apparatus in the aircraft was the blind-approach landing set common to eve German bomber. His opinion was challenged, however, by another scientists, outside the Intelligence organization, who was an acknowledged authority on the propagation of radio waves; for according to this expert it was impossible to make a short wave beam which would bend sufficiently round the curve of the earth from German for it to be heard in a bomber in England. Coming from so authoritative a quarter this pronouncement had threatened to place Jones's hypothesis out of court, and even to cancel the search which eh had just arranged. But the Prime Minister, who had a firm belief in the value of positive experiment, had directly concerned himself in the matter; and it was by his personal order that Jones was allowed to have his way, and that the Anson took off. Its subsequent success was, of course, no more than Jones expected; for the intelligence already at his disposal had enabled him to put the aircraft in the right locality, and on the right frequency, for bringing back confirmation of his theory.
The beam which the Anson had picked up was in fact part of a system know to the enemy as Knickebein ('crooked leg'). The pilot using it travelled along the beam until.it was intersected by another beam, at which point a different note sounded in his ear-phones and he release his bombs. Alternatively, for tactical reasons such as avoiding heavy anti-aircraft defences at a particular place, the beams might be made to intersect a little distance from the target, and the pilot would then drop his bombs after a short timed run along a given course from the point of intersection. The system was accurate to within roughly a square mile, and was thus an admirable device for the mass bombardment of urban areas by night.
The fact that one of these beams was picked up as early as 21st June, several weeks before German night bombing began on a large scale, is good evidence that the Air Ministry was fully alert in the matter of night defence. This is the more worth emphasizing since our failure to inflict any appreciable loss on the enemy raiders was soon to be all too obvious. Indeed, the main problem of the night bomber at this juncture, as long as it kept reasonably high, was not the opposition it would encounter, but the difficulty of locating and identifying its objective in bad weather or absence of moon.
It was this problem which the Germans hoped to solve by the use of radio beams. The early discovery of Knickebein was thus a distinct
score for the defence. As soon as the nature of the system was confirmed, a series of listening posts was set up, and jamming apparatus of a crude type, mad up from hospital diathermy sets, was fitted to a number of vehicles, ready for despatch to target areas. Jammers were also installed in police stations along the East and South coasts, where they could be operated on receipt of a message from Fighter Command. The object of this somewhat rudimentary jamming was simply to blot out the Knickebein signal in the pilot's ears. Far more subtle forms of interference, however, were also devised. These depended on adapting some of our own beam approach beacons to receive the enemy signals, and to retransmit them. The beam along which the pilot was flying could thus be broadened until it lost its original accuracy—an effect which was popularly known as 'bending the beam'—or a cross-beam could be inserted just short of the enemy's planned point of intersection. In either case the bombs were likely to fall wide of the target. By the time the Germans turned to night operations on a grand scale, we were accordingly ready with a number of well thought-out counter-measures. They were, appropriately enough, under the code name 'Headache'.
But Knickebein was not the enemy's only radio aid to navigation at this time. The raiding aircrews also mad great use of their medium frequency direction-finding beacons, which had been extended from Germany up to the Channel. By tuning in to the signals from any two of these beacons, whose locations were well know to them, the raiders could periodically fix their position and ensure that they were steering an accurate course. Fortunately the Post Office radio engineers had already devised in advance a counter-measure to this practice. The enemy signals were picked up and retransmitted in sufficient strength to swamp the original sound in the ears of the German crews, who, ignorant of the true source of the signal, thus mad a false calculation of their bearing. Since the process consisted of 'masking' the enemy beacons it was known as 'Meaconing'. It success depended not only on the skill of the operators but also on up-to-date information of enemy transmissions derived from the ever-alert wireless interception service.
There were other means of misleading the German raiders besides interfering with their radio aids. The experience of 1914–18 had amply demonstrated the value of camouflage in all its many forms, and shortly after the outbreak of war the retired Director of Works and Buildings in the Air Ministry, Colonel J. Turner, had been charged with the development of devices intended to deceive and decoy the enemy. The Colonel, already an expert in such matters, gave his name to a special branch devoted to this particularly pursuit—
'Col. Turner's Department' stands unique in the history of Air Ministry nomenclature—and rapidly succeeded in his object of making the true appear the false, and the false the true. By the time the Germans had finished with France his bogus creations included some seventy dummy airfields, the majority of which had flare paths and appropriate lights to be illuminated on the approach of a raider. The enemy was attracted to these from the very beginning of his night operations over this country, and in June 1940 alone, before the major offensive opened, they drew no less than thirty-six attacks.
It was just as well that there existed these various devices for confusing the German night bombers, since by night neither fighters nor guns possessed a tithe of their daytime efficiency. The basic reason for this was our inability to track enemy aircraft accurately in the dark once they had crossed our shores. Winston Churchill, lamenting the fact that when a raid crossed the coast it left radar to come within the province of the Observer Corps, had once described this as 'a transition from the middle of the twentieth century to the early Stone Age'. By day, in anything like clear weather, the skill of the observers—whose visual plots were extremely accurate, and whose estimates of height and number were a great deal better from those afforded at the time by radar—fully justified reliance on the human eye (and a pair of binoculars). But by night, or in heavy cloud, the absence of effective inland radar told heavily. For the observer Corps then became dependent on sound; and though their tracking was invaluable for the issue of air raid warnings, it was not sufficiently exact for systematic interception or engagement of the enemy.
The guns and the searchlights in fact depended on their won sound-locators for more detailed information of the enemy's approach. But sound-location apparatus varies greatly in accuracy in different kinds of weather, and with the increased speed of modern aircraft it was becoming entirely out of date. An aircraft flying at 20,000 feet and 300 miles per hour would be one and a half miles further on before its sound reached the listening apparatus on the ground, and five or six miles further on before the burst of shells; and during this time it would not—if its pilot was sensible—maintain a constant course.
In mid-1940 neither the gun nor the searchlight could thus open up against the night raider with any reasonable prospect of success. Moreover, even if the enemy were accurately located, guns and searchlights alike were still subject to other limitations. The searchlights, of which there were some 4,000 in Great Britain in July 1940, could neither hold an aircraft for a satisfactory length of time, nor penetrate cloud, nor illuminate effectively above 12,000 feet. After the first few
raids in June, when searchlight-aided fighters scored several successes, the Germans accordingly took care to operate well above that height. The guns were also far from adequate both in numbers and performance. In July 1940 only 1,200 heavy and 549 light guns were deployed in the whole of the United Kingdom. Of the 'heavies' some 200 were of the obsolescent 3-in. type; the remainder were the effective 4.5-in. and 3.7-in. weapons, with a theoretical 'ceiling' of over 30,000 feet, but a practical limitation of 25,000 feet because the predictor in use could not accept greater heights. The light guns, about half of which were of the admirable Bofors model, dealt with aircraft only up to 6,000 feet.
From all the disadvantages of inaccurate tracking and location the fighters suffered fully as much as the guns. It also proved difficult, with the deadly menace of daylight attack still undefeated, to concentrate on the development and production of a specialized night fighter. When the Germans opened their main night offensive in September, we had, in fact, only eight squadrons of fighters primarily allocated to a night role. None of these were equipped with aircraft specially designed for the purpose. Two squadrons of Defiants had recently turned over to night fighting because they had proved incapable of holding their own against enemy fighters by day; the other six squadrons—Blenheims—were night fighters for much the same reason. The Blenheims, however, in spite of their lack of speed—they were slower than some of the bombers they were supposed to pursue—had certain advantages. They were a twin-engined type, with a reasonable endurance; and many of them were already fitted with the airborne radar known as A.I. (Air Interception).
From the very early days in the study of radar, Watson Watt and others had foreseen the possibility of developing suitable apparatus for use in aircraft, both against other aircraft and against vessels at sea. The technical difficulties were very great, however, and priority of research and development was inevitably accorded to the coastal chain of ground stations, which promised immediate results of revolutionary importance. Though intensive work on airborne radar was begun at the Bawdsey Research Station under Dr. E. G. Bowen in 1936, it was thus perforce slower to achieve fruition.
A ground radar station, with its static position, huge aerials on 60-foot masts, and transmitting and receiving apparatus weighing many tons, is naturally capable of detection at a far great distance than a set carried in an aircraft. In the summer of 1940, a ground radar station could 'see' over water for as much as a hundred miles; and A.I. set could 'see' at distances only between two miles and eight hundred feet. It was therefore not surprising that the first three marks
of A.I., though full of promise, and though used operationally by a few aircraft of the Fighter Interception Unit from November 1939 onwards, had not achieved any great success in practice. On 22nd July 1940, an enemy aircraft was at last shot down by an A.I. Blenheim, but in general interceptions were disappointingly few. This was primarily because the limited range of the set demanded more accurate tracking on the ground then was yet available. But there were also other handicaps, including the slowness of the Blenheims and the fact that the A.I. apparatus was not yet mechanically reliable. On the night of 13/14th August, however, the first tests were mad with a new mark of A.I., the Mark IV, which had a maximum range of nearly four miles and a minimum of only six hundred feet. Its worth was soon proved; and about the same time the first Beaufighters—strong, fast machines developed from the Beaufort bomber—began to trickle into service. An effective A.I. in an effective aircraft—the conjunction seemed, and was, highly promising. But in September 1940, such aircraft were too flew in number to have much operational significance. In any case they still lacked the information which could put them within A.I. range of the enemy.
Since the number of specialized night fighters was so small, the ordinary Hurricane and Spitfire squadrons, or rather their more experienced members, were thus expected to do duty by night as well as day. They were neither properly trained nor equipped for this, nor had they good night-flying facilities for their airfields. In bright moon the pilots had not great difficulty in taking off, navigating and landing, but dark or cloudy nights brought fearful hazards. Indeed, it often proved impossible to send our fighters into the air in conditions which presented no obstacle at all to the beam-assisted German bombers.
In sum, our defence against night attack in September 1940, was entirely inadequate. Radar promised well in several directions; but until it had developed to the point of replacing sound-location over land, neither inland tracking, nor gun-laying, nor searchlight exposure could be done effectively. And though an excellent night-fighter with an efficient A.I. had just come into service, the main burden of night fighting still rested with the day squadrons.
What chance of success the Hurricanes and Spitfires had may be seen from an incident in July. It is told in the words of the pilot, Flying Officer T. S. Wade, of No. 92 Squadron:
Although a day-fighter squadron, circumstances demanded that we should make some attempt at continuing our activities into the night, and attempt it was. Of the many night patrols we mad between June and August only one, so far as I can remember, achieved success.
Alan Wright not only saw something, but effectively shot at it. For most of us it was a case of showing the flag to the locals, who no doubt got some satisfaction out of hearing a couple of Spitfires screaming overhead, even if the screams were brought about by our endeavours to get out of our searchlights and subsequent A.A. fire.
One of the quieter nights, as least as far as A.A. Command and the German Air Force were concerned, was that of July 27/28th. A local dance had prematurely accelerated my promotion to the then thin ranks of night-fighter pilots, with the result that after some four nights of practice I found myself defending South Wales against the German invader.
Needless to say, it was an entirely uneventful one-and-a-half hours stooge—uneventful, that is, from an operational point of view.
Almost before I had finished congratulating myself on getting down in one piece, I was being persuaded into a further venture. The fact that the weather was rapidly becoming typical of this country did not apparently outweigh the need for further flag-showing.
I therefore climbed into my Spitfire, climbed up to 10,000 feet, and three-and-a-quarter hours later climbed over the side of my Spitfire at 4,000 feet. In that time all sorts of nasty things had happened.
Having already warned Control that conditions were deteriorating, I felt fully justified in calling the whole thing off and repeating my request to be allowed to return to base, the first occasion in which I had done so having been turned down by higher authority. I might just as well not have wasted my time. My radio had decided to go on strike. It was a doubly aggravating strike, because whilst i could hear with ever-decreasing clarity the Controller's ever-increasing concern for my well-being, he could hear nothing. For me, very lost and very lonely, it was a very unsatisfactory state of affairs. After flying around for something like an hour on highly inaccurate reciprocal courses, I heard a faint and frantic voice suggest that I steer South as there was some suggestion of a plot North of base. It soon became obvious that it must have been some other sucker.
By this time I had quite naturally lost faith in relying on communication with the ground, and resigned myself to putting in further night-flying practice in the optimistic hope of benefiting therefrom at a later date.
Careful engine-handling enabled me to prolong the agony for a total of three-and-a-quarter hours. not wanting to hasten my extinction by trying to crash land, left me with one alternative—which I took. Before doing so, however, I ineffectively tried to get my own back with a final crack at the Controller.
So far as I know, nobody heard my 'Baling out: listening out'. Perhaps it was just as well.
* * *
When the Germans opened their main night offensive, they thus had little to fear from our fighters, and the bulk of the opposition was
supplied by the guns. It was not very effective, as Londoners soon discovered. The first great attack, on 7/8th September, found only 92 'heavies' deployed for the defence of the capital. Most of the raiders came in between Dungeness and the Isle of Wight; and the sound-locators, which were largely concentrated along the Estuary approach, were either out-flanked or swamped by the large numbers of aircraft. In addition communications failed between many of the vital points. In fact the system broke down completely, and many of the guns did not go into action at all.
Within forty-eight hours of this opening blow London's heavy-gun defences were more than doubled. But numbers in themselves were not guarantee of efficiency, and since existing methods of fire control showed no signs of being able to deal with the attacks, on 11th September many of the crews were given a free hand. The result was an orgy of what General pile describes as 'largely wild and uncontrolled shooting'. Expenditure of ammunition was prodigious, but no enemy aircraft were shot down. Nevertheless the German pilots showed a healthy respect for the increased volume of fire; all of them operated from a greater height, and some of them turned back short of their objective. The damage to the centre of the capital was correspondingly less than on the previous night, while the sound of the 'barrage', after the spasmodic firing to which they had thus far been treated, came as music to the ears of the inhabitants.
The nightly assault on London continued without respite from 7/8th September to 12/13th November. Over the whole of this period there were only ten nights in which the Germans' effort did not, according to their own method of reckoning, amount to a 'major raid'—one, that is to say, in which they dropped at least 100 metric tons of explosive. Occasionally the enemy's activity was reduced because of bad weather, but normally the attack, extending over many hours, was carried out by between 150 and 300 bombers. It was an ordeal which for sheer continuity was not to be exceeded on either side during the war. But London is a large place, with a spirited population; and few of the enemy aircraft carried much more than ton of bombs. Unless the raiders could destroy key points like power-stations and gasworks—and fortunately they showed very little ability in this direction—they would be in for a long job.
The point was not at once appreciated by the enemy. 'German airmen, comrades!' wrote Göring in an Order of the Day to the Luftwaffe crews on 18th October, 'you have, above all in the last few days and nights, caused the British world-enemy disastrous losses by uninterrupted, destructive blows. Your indefatigable, courageous attacks on the heart of the British Empire, the city of London with its
8½ million inhabitants, have reduced British plutocracy to fear and terror. The losses which you have inflicted on the much vaunted Royal Air Force in determined fighter engagements are irreplaceable.…'Later this confidence was to evaporate.
By mid-November, when the Germans adopted a change of plan, over 13,000 tons of high explosive and nearly 1,000,000 incendiaries had fallen on London. Outside the capital there had been widespread harassing activity by single aircraft, as well as fairly strong diversionary attacks on Birmingham, Coventry and Liverpool, but no 'major raids'. The London docks and railways communications—the enemy's favourite aiming points—had taken a heavy pounding, and much damage had been done to the railway system outside. In September there had been no less than 667 hits on railways in Great Britain, and at one period between five and six thousand wagons were standing idle from the effect of delayed action bombs. But the great bulk of the traffic went on; and Londoners, though they glanced apprehensively each morning at the list of closed stretches of line displayed at their local station, or made strange detours round back streets in the buses, still got to work. For all the destruction of life and property, the observers sent out by the Ministry of Home Security failed to discover the slightest sign of a break in morale. over 13,000 civilians had been killed, and nearly 20,000 injured, in September and October alone; but London had adjusted itself to its new existence with astonishing calm. Wardens, firemen, rescue and salvage teams, repair gangs, bomb disposal squads, ambulance drivers, nurses—and plain workers and housewives—all were cheating the Luftwaffe of its triumph.
More than 12,000 night sorties were flown by the Germans over Great Britain during this phase of concentrated offensive against the capital. but in the whole period from 7th September to 13th November our night defences were able to claim the destruction of only 81 enemy aircraft—54 by the guns, 8 by the fighters, 4 by the balloons, and the remainder by other causes. Assuming that these claims were underestimated by about a third—it is impossible to distinguish on all occasions the night losses from the daylight losses in the German records, but after the daylight attacks died down the one-third margin of error becomes apparent—the German casualty rate, at less than one percent of sorties, was extremely light. With a first-line strength of over 1,400 long-range bombers, and some 300 emerging each month from the factories, the enemy would have no difficulty in sustaining his attacks indefinitely.
The defences might be having little immediate success, but at least every effort was being made to improve them. During these autumn
months many projects, most of which had already been under consideration or development before the attacks opened, were pressed forward with the utmost speed. In the First World War the Services had been widely accused of resistance on principle to all new ideas, but no such charge could be laid against them in 1940. Indeed, they proved willing to try almost anything. The P.A.C. apparatus had already shown what fantastic feats of ingenuity the Air Ministry was prepared to incorporate in our defensive system, but even this was overshadowed by the 'long aerial mine'. Under pressure from the Prime Minister and the Admiralty, much time and energy was expended on this weapon, which was nevertheless given tee somewhat discouraging code-name of 'Mutton'. It consisted of 2,000 feet of piano wire with a parachute at the top end and a small bomb at the bottom. The intention was to unspool a number of these contraptions from patrolling aircraft, so that they formed an apron in the predicted path of the enemy bombers. When a raider struck one of the wires the pull of the parachute would bring the bomb up against his wing where it would explode.
Many tedious hours, with occasional interlude of unpleasant excitement, were spent by the test pilots of the Royal Aircraft Establishment flying into practice weapons of this character.1 By October No. 420 Flight (later No. 93 Squadron), Middle Wallop, was detailed to employ 'Mutton' operationally. In spite of great efforts on the part of scientists and aircrew alike the project enjoyed singularly little success, and after the main enemy assault was over it was officially abandoned. A similar lack of success met the attempt to operate a free-balloon barrage—a curtain of bombs suspended by wire from balloons released in the path of the enemy. Both ideas failed, not from technical imperfection, but from the sheer immensity of space open to the attackers.
It was also during this period that Wing Commander W. Helmore's proposal for an airborne searchlight came to the fore. The scheme involved fitting a suitable light in an A.I. aircraft, and then operating this for the benefit of an accompanying fighter, which would carry out the actual attack. The technical problems involved were formidable, and though the device was developed with exceptional speed, it was not until the enemy's main offensive against this country had ended that 'Turbinlite' aircraft were ready for use. Ten flights were then rapidly fitted, but the difficulty of cooperating with the
attendant fighter and the inherent imperfections of searchlights in thick weather prevented any great success.
Though the Air Ministry rightly neglected no field of experiment, the real hope for the future depended, as Dowding and Pile constantly stressed, on perfecting and producing certain radar apparatus. A few radar sets for gun-laying (G.L.) were already in existence, but they were unable to give readings of height until an elevation-finding attachment was developed. This was introduced into the London defences at the beginning of October, which after 'unseen' barrages could at last be fired with a reasonable chance of success. The set, however, still had many defects at angles of sight above 45°, and these had to be overcome, and the new equipment produced in quantity, before the guns could inflict any great losses on the raiders. Meanwhile radar was also adapted for the special requirements of searchlight control (S.L.C.).
A most promising prospect had in addition opened up for the fighters. By the summer of 1940, the scientists at the Air Ministry Research Establishment (later the Telecommunications Research Establishment), aided by a powerful contribution from the radio industry, had evolved radar apparatus for a long-distance inland tracking. As soon as its worth was established a 'crash' programme of twelve sets was put in hand, and in mid-October the first operational station opened at Shoreham. Is range was some 45 miles; and by a novel scheme known as the Plan Position Indicator the controller was able to witness a simultaneous presentation of the attacking bomber and the intercepting fighter in relation to the surrounding countryside. By passing directions over the R/T the controller could place the fighter within a thousand yards of the bomber; once the fight pilot was within that distance, his A.I. would bring him into visual contact with the enemy. The new apparatus, which became known as a ground-controlled interception set (G.C.I.) was, in conjunction with A.I., to revolutionize the science of night defence. It had, however, the serious limitation that it could not control one, or at the most two, interceptions at a time.
In essence, our chances of success now rested on the speed with which the new radar apparatus and the Beaufighters could be brought into service. But many subsidiary improvements in the night fighting system were also required. The investigations of specially constituted Night Defence Committee under Marshal of the Royal Air Force Sir John Salmond, and including such agile brains as those of Air Marshals Freeman, Joubert, Tedder and Sholto Douglas, showed the way. The Committee recommended special optical tests in the selection of night fighter pilots, specialized night training at a
night fighter O.T.I., a special night operations staff at Fighter Command, and navigational aids for night fighters. All these suggestions were carried out in the ensuing months.
At last, then, there was hope of better things for the future. Meanwhile, if we were not shooting down any great number of enemy aircraft, we were certainly—though the public did not know it—diverting many of them from their objectives. Colonel Turner's dummy airfields, decoy fires and the like were drawing some five percent of the enemy air effort, and a great deal more was going astray through our interference with Knickebein. Indeed, by November the German pilots had become thoroughly distrustful of this radio aid. Experienced crews, according to the evidence of captured prisoners, were able to disregard our counter-measures, but there was a general, and natural, reluctance to steer a course which was apparently well-known to the defences. A number of our fighters equipped with 'Lorenz' apparatus had, in fact, been instructed to 'hunt up and down the beam'. They had not secured any victims, but their presence—or their suspected presence—was thus proving a powerful deterrent.
One of the early German advantages had now been largely nullified. But war in the ether is a relentless battle of wits between experts who are adept at seeing more than one step ahead at a time. The Germans were not without an alternative radio navigational system for the fresh phase of their offensive which was about to begin' and Air-Vice Marshal's Addison's No. 80 Wing, our newly formed radio countermeasures headquarters at Radlett, was not without a shrewd idea both of what it was, and of how to deal with it.
* * *
'During the night offensive I finally secured the Führer's permission to attack other objectives besides London, because it was always my contention that attacks on the British war industries would be much more valuable. I argued that it was no use to us to have another hundred houses to up in flames. I wished for attacks on the aircraft plants in the South of England and around Coventry, the shipping yards, Glasgow, Birmingham and the ports … I told the Führer again and again that in as much as I knew the British people as well as I did own my own, we should never force them to their knees by bombing London.'
Thus Göring to the author of the latter part of this history in April 1946. At such a date the ex-Commander-in-Chief of the Luftwaffe was naturally inclined to minimize his own responsibility for the assault on London; but there is little doubt that as the attacks on London progressed, his own enthusiasm for them diminished. Indeed,
after 12th October, when the projected invasion was postponed until the following spring, it was clear that their primary purpose had failed. Henceforth correct strategy would aim, not at the demoralization of the capital, but as the emasculation of British trade and war industry.
The forthcoming change in German objectives was sensed by our Intelligence, and by 12th November we knew that three great attacks, called by the Germans with unwonted humour 'Moonlight Sonata', 'Umbrella' and 'All-One-Price', were soon to delivered against Coventry, Birmingham and Wolverhampton. Indeed, there was just time to plan a counter-operation—'Cold Water'—by which Bomber Command would simultaneously harass the enemy's bomber airfields and retaliate against a selected German town. It is a striking illustration of the advantage then held by the German that though this information was in our hands, and though attacks against their airfields were duly carried out, Coventry and Birmingham were both heavily smitten within the next few nights. Wolverhampton, more fortunate, escaped. The sudden increase in its anti-aircraft defences was possibly observed by the enemy.
The new phase of the German offensive began on the night of 14/15th November, as the inhabitants of Coventry will long remember. The weather—full moon and good visibility—favoured the attack, and the German operation went more or less according to plan.
The first raiders crossed our coast at 1817 hours, when about a dozen enemy aircraft made landfall at Lyme Bay. They were the He.111's of Kampfgruppe (K.Gr.) 100, the unit which specialized in blind-bombing against precision targets. Using a highly complicated radio-aid system known to the Germans as the 'X' Gerät,2 the unit had already enjoyed some success in individual attacks against bridges in Warsaw and aircraft factories in the British Midlands. Now, however, its role was different. Since our interference with Knickebein had proved so successful, and since there was no other radio-aid with which the whole of the German bomber force was fitted, K.Gr.100 were to employ their special technique in a path-finding capacity. Their task was to find the target , shower it with incendiaries, and leave it well ablaze. The rest of the bomber force would follow up and bomb the fires.
K.Gr.100 arrived over Coventry at 2015 hours. Meanwhile the main force was already approaching from a number of different
directions. One stream led in across the Lincolnshire and Norfolk coasts: another between Selsey Bill and Portland: a third between Selsey Bill and Dungeness. All told, 437 enemy aircraft operated, keeping up the attack until shortly before 6 o'clock the following morning. Between them they dropped 56 tons of incendiaries, 394 tons of H.E. bombs and 127 parachute mines.
In view of our popular conception of this raid as a virtually indiscriminate assault on a city centre—and certainly the parachute were not a precise weapon—it is not without interest to discover that many of the German aircraft were given specific targets. I/L.G.I. was to attack the works of the Standard Motor Company and the Coventry Radiator and Press Company; II/K.G.27 the Alvis aero-engine works; I/K.G.51 the British Piston Ring Company; II/K.G.55 the Daimler works; and K.Gr.606 the gas-holders in Hill Street. Most of these objectives were in fact fairly heavily hit.
Twelve important aircraft plants and nine other major industrial works suffered directly from the attack, but output was also affected by general damage to utilities. Only one power plant was actually hit, 200 fractures of gas mains—and the shortage of gas and water was felt for some time. Indeed several factories were compelled to suspend production solely for this reason. The disorganization of transport was another great handicap—all railway lines were blocked, and all road traffic except the most essential had to be diverted round the city—and the loss of some 500 retail shops greatly hampered the distribution of food.
Recovery from the general disorganization, however, was surprisingly quick. Help was rapidly forthcoming both from the regional authorities and the ministries in London. All railway lines except one were re-opened by the 18th. The large numbers of unexploded bombs were speedily dealt with, and within three or four days there was an excellent service of transport to take workers to the factories, evacuate the homeless, and disperse key tools from the damaged works. And despite the fact that 380 people had been killed and 800 seriously injured, morale remained unshaken. On the evening of the 16th arrangements were made to transport 10,000 people out of the centre of the city. Only 300 used them.
The results of the raid would, of course, have been much worse but for the fine work of the local civil defences and the voluntary helpers. The guns, too, had maintained a fierce barrage which kept the enemy high. Among the many who carried out their duties unflinchingly throughout the grim ordeal were the men of the Observer Corps, whose operations room was uncomfortably close the blazing
Cathedral. Mr. Gilbert Dalton, a Chief Observer, has described how for twelve hours members of the Corps sat around the table, and plotted the tracks of the raiders. 'The building', he writes, 'was frequently shaken by bombs—more than twenty detonated within a short distance—and surrounding buildings were on fire, but the work went on. Lights failed; candles were lit. Smoke drifted in through the ventilating system. Water from firemen's hoses swilled into the room. Telephones went dead; plots were still received and told to the R.A.F. on the lines that remained. men whose homes and families were in the city went stolidly with their work' one member that night lost his house, his business and his car, but he reported for duty next day. A number of members got through as reliefs during the height of the blitz; one man took three hours to come two miles because of the fires and obstructions.'
The next two nights the enemy, anxious not to let the capital benefit unduly from his change of plan, reverted to attacks on London. on the 17/18th November he struck at Southampton; then followed three nights of heavy raiding against Birmingham. In the last week of the month Southampton, London, Liverpool, Bristol and Plymouth all received 'major raids'. Further ordeals followed in December, and Manchester and Sheffield were added to the list of stricken cities. The year went out with the City of London still smouldering from the fire-raising attack led by K.Ge.1000 on 29th December.3
Göring pursued his policy of ringing the changes between three main target groups until the latter part of February, 1941. Of the thirty-one 'major raids' carried out between mid-November and that date, fourteen were on ports, nine on inland industrial towns and eight on London. Apart from minor nuisance activity, the enemy's effort was usually concentrated each night against a single centre; and he developed the unpleasant habit of bombing the same city twice or three times at brief intervals in the hope of impeding recovery. In January, though three fresh centres—Cardiff, Portsmouth and Avonmouth—had their first heavy night attack, the German attacks were much reduced by the weather. February saw a still further decline, with only 1,200 sorties as against over 6,000 in November and 4,000 in December.
During this time the defences were certainly not idly, though they were still destroying very few enemy aircraft. In the four months
from the beginning of November to the end of February the enemy put at least twelve thousand sorties over this country, but the total number of aircraft claimed as destroyed by the defences was not more than seventy-five. Of these approximately two-thirds were claimed by the guns, one third by the fighters.
Fortunately our success in diverting, as opposed to destroying, enemy aircraft was much greater. Although at first we had nothing available with the correct frequency range for interfering with k.Gr.100's 'X'-Gerät, suitable jamming apparatus was soon developed. Indeed, during the early months of 1941 the Germans became so impressed with our radio counter-measures that they no longer set up their beams the afternoon before the attack—except sometimes to mislead us by directing them against a false target. Instead they waited until their aircraft were crossing the British coast. Our customary foreknowledge of the enemy's objective—a surprising feature which would have caused some disquiet had it been commonly appreciated—was to that extent reduced; but there was also a corresponding reduction in the efficiency of the German system. Moreover, by January we were using one of Colonel Turner's devices—the decoy fire, or 'Starfish'—in very effective conjunction with our information of German intentions; for a decoy will naturally deceive the enemy more completely and attract a much greater number of his bombs if it is ignited along his predetermined line of approach.
All told, though we were still far from having the measure of the night bomber, we were on the verge of better things. Above all, the active defences were being developed along the right lines. Pupils from the new night fighter O.T.U. were beginning to enter the squadrons; night-flying facilities were improving; the first G.C.I. programme was being completed with astonishing speed. The guns, too, were growing steadily more efficient. The 20,000 rounds per aircraft destroyed in September had dropped to less than 3,000 in February, and the first of the new batteries of rockets, or unrotating projectiles (U.P.), was at last in action. The results were to be seen in the next, and final, phase of 'The Blitz'.
* * *
By February 1941 the German High Command was becoming critical of what had thus far been achieved. The doubts of Keitel and Jodl were powerfully reinforced by those of Raeder, who took the opportunity of a conference with Hitler on 4th February to point out that the Luftwaffe's attacks had neither crippled British production nor shaken British morale. Britain's vulnerable points, the German admiral urged, were her dependence on imports and her shortage of
shipping space. German air strategy should concentrate on exploiting these weaknesses.
This, of course, was already part of the German plan of campaign. But from now on it was given 'top priority'. Since the German Army, according to the plan now current, would be fully occupied with Russia by the following May, Britain must be brought to her knees through a blockade exercised jointly by the German Navy and the German Air Force. While the U-boats dealt with our ships at sea, Göring's bombs must shatter our ship-yards and lay waste our ports. At the same time they must still keep the Royal Air Force in check by occasional attacks against the air armament industry. On 6th February this policy was incorporated in a formal directive from Hitler.
When better weather again made intensive operations possible, the Luftwaffe thus turned in strength against the ports, and in particular against those most used in the vital traffic across the Atlantic. Between 19/20th February and 12th May the enemy carried out sixty-one attacks involving more than fifty aircraft. Seven of these—most of them very heavy—fell on London, five on Birmingham, two on Coventry and one on Nottingham. The remaining forty-six were all directed against the ports. Portsmouth, Plymouth, Bristol and Avonmouth, Swansea, Merseyside, Belfast, Clydeside, were all heavily and repeatedly bombed. On the east coast Hull became an increasingly favoured target, while Sunderland had one big raid and Newcastle—thanks to a suggestion made by a former French Consul—two. In addition there were many minor raids, as well as individual attacks on ships and constant mine laying.
In each of the places attacked the enemy certainly left his mark. But his triumph was no longer cheap or easy. By March the A.I.; squadrons in Fighter Command were all equipped with the new Mark IV apparatus, and five of the six had changed their Blenheims for Beaufighters. The following month the number of G.C.I. stations handling these aircraft rose to eleven. moreover, the eight squadrons of ordinary Hurricanes and Defiants allocated exclusively to night operations were gaining rapidly in skill and experience. There was also the 'Intruder' Squadron—No. 23—which since December had harassed the German airfields and generally interfered with their night activities at source. As soon as the enemy's new plan of campaign became apparent, all these resources were skilfully disposed by Sholto Douglas to give the greatest possible protection to the ports.
In January the night fighters had been able to claim only three enemy aircraft destroyed, the guns twelve. In February the figures were much the same—four by the fighters, eight by the guns. But
from then on the totals showed a welcome and encouraging rise—a rise, moreover, in which the fighters began to outstrip the guns. During March the fighters claimed twenty-two of the night raiders, the guns seventeen. In April the figures were better still—forty-eight and thirty-nine. In May, though the enemy's effort had already slackened before the end of the month, a peak was reached with a claim of 96 by the fighters, 3½ by the guns, 10½ by other causes
This, though still no more than 3.5 percent of the German sorties over the month, was a far cry from the complete failure of the previous autumn. Numerically the fighter successes were divided fairly equally between the ordinary 'cat's eyes' fighters and the A.I. aircraft operating under G.C.I. control. But it was noticeable that since January the latter had obtained nearly twice as many 'contacts' as the former, though they had flown less than half the number of sorties. It was thus with the A.I./G.C.I. that the future lay; for the normal fighter, even when flown by a fully-trained night-pilot, was really effective only against a highly concentrated attack delivered on a very bright night—a 'fighter night;, when gun-fire could be kept down (much to the chagrin of the gunners and the perturbation of the local population) and the skies above the target given over to close patrols of Defiants and Hurricanes or even, on occasion, Hampden bombers. The A.I./G.C.I. combination, on the other hand, did not depend for its success on a dense concentration of raiders; and though it was many times more efficient in moonlight than otherwise it was capable of securing results in conditions which completely baffled the 'cat's eyes'.
How the pilot and his A.I. operator in the air worked with the G.C.I. controller below may be seen from a typical combat report. The date is the night of 11/12th April 1941, the aircraft a Beaufighter of No. 604 Squadron, the A.I. operator Sergeant C. F. Rawnsley, the reporting pilot Squadron Leader John Cunningham. The necessary explanations have been added.
Put on to north-bound raid 13,000 feet. Final vector 360° and buster [full speed].
Told to flash [to operate A.I.] but no contact received. [G.C.I. station] then told me to alter course to 350° and height of 11,000 feet. While going from 13,000 to 11,000 feet a blip [flash of light in A.I. set] was picked up at max. range ahead. On operator's instructions I closed in and obtained a visual at 2,500 feet range (checked on A.I. set) and about 30° up.
Identified E/A [Enemy aircraft] as He.111 which was flying just beneath cloud layer and occasionally going through wisps which allowed me to get within 80 yards of E/A and about 20–30 ft. beneath before opening fire.
Immediately there was a big white flash in the fuselage centre section and black pieces flew off the fuselage. E/A went into a vertical dive to
the right and about half a minute later the sky all around me was lit up by an enormous orange flash and glow. Bits of E/A were seen to be burning on the ground.
I estimated my position to be about Shaftesbury but called Harlequin and asked for a fix so that my exact position could be checked
One He.111 destroyed.
Rounds fired 64.
Cunningham and Rawnsley, it may be remarked, were to continue on these lines for a long time to come. They soon became the outstanding night-fighter crew of the war, and won between them no less than nine British decorations.
The diversionary defences, like the night fighters, proved very successful during the final phase of the German attack. On the night of 17/18th April, for instance, when a heavy raid was taking place on Portsmouth, a 'Starfish' site was lit on Hayling Island. It attracted 170 high explosive bombs, 32 parachute mines and 5,000 incendiaries.
Radio counter-measures were no less effective. As a result the 'Y'-Gerät.4 The essential features of this had been deduced in advance by R. V. Jones of Scientific Intelligence, and it was jammed at the enemy's very first attempt to bring it into use. By the end of April, III/K.G.26, the pathfinding unit trained to operate with this device, had as little confidence in it as K.Gr.100 had in the 'X'-Gerät.How the decoy fires and the radio counter-measures worked together was shown very strikingly in the closing weeks of the enemy's offensive. On the night of 8/9th May German bombers were ordered to attack Derby and Nottingham. The attack on Derby was to be led by K.Gr.100, and 'X'-Gerät beams were set up to cover the Rolls-Royce works. They were detected, and radio counter-measures applied, with the result that Derby escaped entirely and the German effort spent itself on the moors to the north-east of the town. Apparently in the course of this diversion, some of the bombers attacked Nottingham, the target for the other force. To distract the, a decoy fire was lit outside the city. Seeing this ahead, many of the pilots scheduled to attack Nottingham imagined the fire to be Derby burning from the attack of their comrades, and concluded that they were slightly off course. They accordingly 'corrected' by steering further to the east. The result was that the Vale of Belvoir, which is
roughly the same distance east of Nottingham as Nottingham is of Derby, received 230 high explosive bombs, one oil bomb, and several groups of incendiaries, with a total casualty roll of two cows and two chickens. The following morning the German communiqués claimed great success at both Nottingham and Derby, including heavy damage to the Rolls-Royce works. The whole episode was the more surprising in that it occurred on a night of bright moon, when the difference between town and country—and real and decoy fires—should have been perfectly apparent to the enemy.
As the German Army began to mass in the East and to secure its right flank in Greece and Yugoslavia, the German Air Force struck with redoubled fury in the West. If the intention was to cover up the forthcoming offensive against Russia, it was singularly unsuccessful. But doubtless the main motive was to do as much damage as possible in the short time remaining. In the second half of April London was twice raided with a greater weight of high explosive than ever before—876 tons on the memorable 'Wednesday' (16/17th ), 1,010 tons on the 'Saturday' (19/20th). Between came Portsmouth's heaviest attack; then followed four grim nights for Plymouth. The next month was ushered in by the sustained assault on Merseyside and by savage raids against Clydeside and Belfast; and in a final fling on 10/11th May, London was treated to another 700 tons.
But by then Göring's units were on the move, and in the next two months only four attacks of over a hundred tons were delivered against British targets. By the end of June two-thirds of the Luftwaffe's strength had been withdrawn east and south. Like a prisoner slow to comprehend the news of his release. England saw 'The Blitz' degenerate into 'seaside tip-and-run' and was scarcely aware that the long ordeal was over.
In terms of strict economics, the German offensive had certainly been a profitable venture for the enemy. British aircraft production had been seriously impaired, both by direct damage and enforced dispersal of plant: not until February 1941 did output again approach the level of the previous August. The steel and ship-building industries, communications, power supplies, stocks of food and oil, all had suffered. Over 600,000 men had been kept tied down to ground and civil defence. Some 40,000 British civilians had been killed, another 46,000 injured, and more than a million houses damaged. All this had been accomplished for the loss on night operations of some 600 German aircraft—nearly a third as many again as we claimed at the time, but still only 1.5 percent of sorties. The great Coventry raid, which for a short time caused a decline of 20 percent of our aircraft output and cost us many hundreds of machines before production was
fully restored, had been carried out for the loss of one German bomber.
Yet 'The Blitz' was very far from being a great strategic victory for the enemy. Widespread though the damage was, its effects on general industrial production was not of vital importance. In five months of intensive raiding on docks and ports in 1941, only some 70,000 tons of our food stocks were completely destroyed, and only one half of one percent of our oil stocks. Damage to communications was quickly repaired. Everywhere except in the aircraft industry the loss was too small a fraction of total output to matter seriously.
This was partly because the German night offensive, like the daylight attacks in the Battle of Britain, suffered from confused direction. Our great power installations provided one good target system; the aircraft industry was another—though dispersal complicated the German task; the ports and dockyards were a third. But the Germans vacillated between these different systems, and mingled attacks on all three with mere terrorism. And since most of the bombs in any case fell wide of their target—an effect which must be ascribed in great part to our defences—much of the German activity was wasted, although it certainly made matters uncomfortable for the civil population. The campaign was conducted cheaply enough, and the Germans had good value for their expenditure in aircraft and crews. But except in so far as it forced us to retain at home guns and fighters which were badly needed by our hard-pressed forces in the Middle East, it got them nowhere.
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1 'Impact trials' were also carried out by these pilots to develop, amongst other things, cable-cutters, de-icing equipment, rocket-projected mines, and the 'double-parachute link' (steel cable joining two parachutes, either for incorporation in a balloon-barrage cable or for firing by rocket).
2 The aircraft flew along a fine beam in the centre of a coarse beam. this was intersected by three beams near the target—the first as a general warning, the second as the 'preliminary signal', the third as the main signal. From this third point of intersection it was than a short predetermined distance to the target. A device set in motion by the observer on arriving at these cross-beams released the bombs automatically.
3 The damage caused purely by fire in this raid, and in those on Manchester, showed the vital need for teams of fire-watchers in office premises, public buildings, streets, etc. A general obligation to fire-watch was introduced on 18th January 1941. The creation of the National Fire Service followed in August.
4 This depended on the combination of a single beam with a system of ranging—i.e. determining the position of the aircraft along the beam at any given time, so that a signal for the release of the bombs could be sent at the right moment.