A Tribute to H.C "Bill" Sykes, The Developing Technology of the RAF Strategic Bombing Campaign a comprehensive account by a W.W.II Bomber Command veteran who died 8th January 2001 RAF Strategic Bombing: From Art to Science and Back by H.C "Bill" Sykes 223 Sqn RAF Introduction This account summarises the story of Bomber Command's heavy bomber offensive against the German Fatherland from the beginning of the Second World War until its end. It does not attempt to cover the significant contribution of the United States Army Air Force. It does, however, tell something of the Germans' fight to defend their homeland. The booklet was conceived as a source of background information for visitors to the Battle of Britain Memorial Flight which, when it opened its hangar to the public in 1986, attracted over 13000 visitors in its first year and almost 25000 in the year ended April 1989. They came to see one of the two remaining Lancaster bombers still flying and the Flight's two Hawker Hurricanes and five Supermarine Spitfires, which also fly regularly. The Flight frequently hosts parties of schoolchildren whose visits are organised as part of specific projects within the school curriculum and it is hoped that the answers to questions which these visitors and others meant to ask during their trip will be found in the following pages. No attempt has been made to describe particular raids or events in detail because to try to do so in a booklet this size would be impossible and would leave too many heroic deeds undocumented; rather, it tries to chronicle in more general terms the bombers' struggle to find their way, achieve their objectives and get back safely to fight on. There is at the end a bibliography and a glossary of terms which may be unfamiliar to some readers. The author, who is a voluntary civilian guide with the Flight, returned safely from over thirty operations over Germany with Bomber Command in World War Two. This booklet is therefore dedicated with considerable humility and respect to the memory of the 55,500 Bomber Command aircrew who did not return. Grateful thanks are due to Messrs John Larder, Peter Bond, Derrick Clarey and Richard Jones who provided the art work, Mr H. van Geffen for the detail on the work of the 101 Squadron Special Operators and Mr G.Watson who undertook the printing at cost.  H.C."Bill" Sykes, 1989

I. The Beginning The effectiveness of a bombing force, measured by its capacity to deliver high explosives and incendiary devices in quantity upon its opponents at the minimum cost to itself in men and materials, depends on three factors; a reliable means of conveyance, the skill to find the targets with accuracy and the ability to avoid or resist the hostile intentions of their intended recipient. At the outbreak of World War 2 the RAF had bomb carrying capacity with its Armstrong Whitworth Whitleys, Handley Page Hampdens, Fairey Battles, Bristol Blenheims and Vickers Wellingtons, albeit modest by its later standards. As weapons, however, these aircraft were sadly lacking in accuracy and defensive armament. The undoubted courage and skill of the aircrews, largely time-serving professionals and reservists, were not enough to overcome these shortcomings but the lessons these men were to learn the hard way laid the foundations for the awesome destructive machine Bomber Command was to become. The embryonic Bomber Command entered the arena the day following Britain's declaration of war. On the 4th of September 1939 a force of 15 Bristol Blenheims and 14 Vickers Wellingtons took off to attack units of the German Navy in the Heligoland Bight. Blind bombing being something of a pipe dream at that time the attackers were forced to go in below a particularly low cloud base which brought them within the range of the light flak of the heavy cruiser Admiral Scheer and the cruiser Emden. The operation cost 5 Wellingtons and 2 Blenheims - a high price to pay for the superficial damage done to the warships. Further assaults on the German Navy followed during the remainder of that year with little to show for the operations apart from a mounting toll of RAF losses. This preoccupation with the Heligoland Bight - a heavily defended area which became known as the "Hornet's Nest" because of its heavy concentration of flak ships - was dictated by Government policy at that time which decreed that only military or naval targets were to be attacked and that sorties on the German mainland were to be restricted to leaflet dropping (called "Nickelling") in the hope that all-out war could be averted. The fact that Germany's capacity for reprisals with its 2130 bombers against the RAF's 536 at the outbreak of war no doubt also had a bearing. This early blooding did however provide the RAF tacticians with food for thought which crystallised into two concepts; that raiders should fly higher and remain in formations which would enable them to cover each other with their own defensive armament. The best British bomber at that time was the Barnes Wallis designed Wellington and it was argued with some justification that a formation of these aircraft with their pairs of rifle calibre .303 Browning machine guns in their nose and tail turrets and another pair in a ventral turret which could be lowered and manned when needed, could undertake daylight raids with impunity without fighter cover. The argument was settled in the most cruel fashion when it was first put to the test. On the afternoon of 18th December 1939 22 Wellingtons ("Wimpys" as they were affectionately known to their crews) from three squadrons were once more over the Heligoland Bight. Flying at 14000 feet they located targets in the harbour at Wilhelmshaven but turned away without bombing because of the ban on bombing in areas where bombs could fall on the mainland. Their sweep, was picked up by the German early warning radars (codenamed Freya) but their height afforded them some immunity from anti-aircraft fire. However as they turned towards home they were intercepted by 32 single engined Messerschmitt 109s and 16 Messerschmitt 110 twin-engined fighters, mostly armed with 20mm cannons. Only 10 of the Wimpys, 3 of which were severely damaged, returned to their base. The Luftwaffe with its superior numbers and weaponry did not have it all its own way however, because most of the attackers received some sort of damage, but the actual cost to them was only 3 of the single engined Messerschmitt 109s. Thus, the RAF tacticians learned as the Luftwaffe and the United States Air Force were to learn later that, however heavily armed, unescorted bombers could not successfully mount daylight raids in the face of spirited fighter opposition. The options left to Bomber Command if it were to survive were either to seek fighter cover or fly by night. As there was a powerful school of thought which regarded the use of fighters in this way as something of a waste of resources it was inevitable that, as the Germans with their Gotha bombers and Zeppelin airships were forced to do in World War I, the switch was made to night attacks. The early night raids by the Whitleys of 4 Group were, to the disgust of Air Vice Marshal Harris their C.O., confined to leaflet dropping. Harris, who in February 1942 was to become the Commander in Chief of Bomber Command, dismissed his Group's activities rather inelegantly with the comment that supplying the enemy with free toilet paper was hardly likely to induce surrender! These "White Bomb" raids did, however, provide invaluable training for what was to come. The first night bombing raid on German soil took place on 19th March 1940 when 20 Hampdens from 5 Group and 30 Whitleys of 4 Group set out to attack the German seaplane base at Hörnum on the island of Sylt. The change in tactics appeared vindicated because the raid was accomplished with the loss of only one aircraft. However, because of the inaccuracy of the D.R (Dead Reckoning) system of navigation it is hardly surprising that a subsequent reconnaissance flight failed to disclose any damage whatsoever. Under that system navigators on board each aircraft attempt to find their way, much as mariners do, assisted by little more than meteorological reports of wind velocity and radio or star fixes. Even with an experienced navigator this method of navigation can have an error rate as much as 7 miles each side of the intended track for each 100 miles flown. A margin which would not have been so bad if the crews could have reassessed and corrected by visual means on arrival but, in wartime, blacked-out targets were unlikely to provide any assistance in this way. Further, the intrinsic inaccuracy of D.R. would have been compounded where the intruders are harassed by flak or fighters.

II. Into The Valley A significant milestone was passed on 15th May 1940 when, following an attack on Rotterdam by German bombers, Winston Churchill authorised a partial lifting of the embargo on German mainland targets. That day 99 British bombers set out to raid oil and rail depots in the Ruhr valley (a heavily defended industrial conurbation which included the giant Krupp armaments factory at Essen) which became known to the thousands of aircrew who were to follow in their footsteps as "Happy Valley". A wry description for an area which was to claim so many lives, British and German. While the RAF was thus engaged in seeking to improve its effectiveness and establish the future role for its bombing arm the Germans also had problems. At the outbreak of war the German High Command considered that their air defence system was more than adequate to deal with any enemy rash enough to contemplate an attack upon the Fatherland from the air. The fiasco of the RAF's daylight attack upon Wilhelmshaven in December 1939 gave adequate testimony to the Luftwaffe's strength both numerically and in the quality of its already battle-hardened personnel. The sadly disorganised French Air Force fared even worse than the RAF, and its night attacks were easily contained by the combination of searchlights, flak and night fighters. The German Minister for Air, Hermann Goering, gave voice to this confidence when he promised the German people that he would not allow the Fatherland to be exposed to a single bomb. However, the Ruhr raid of 15th May, although not particularly effective, forced a rethink. The unexpected switch to night bombing served to blunt the effectiveness of the Luftwaffe initially so that, at the start of the night offensive, the defenders had to rely upon about 450 heavy flak guns backed by a hundred or so searchlight batteries. The guns were grouped in fours with a predictor (a device used to estimate where the aircraft would be by the time the shell reached it and thus provide information as to where to aim). The searchlights were sited in threes with a sound locator which, as its name implies, located the position of an aircraft by fixing on the sound of its engines. The range of the sound locators was about 6000 yards but, in view of the time taken for the sound to reach the instrument, the calculated position of the target could be up to a mile behind its actual position, a discrepancy which had to be allowed for in aiming the guns. When the flak batteries pinpointed an aircraft the guns were fired in salvoes designed to burst in a sphere of 60 yards in diameter in which it was hoped to entrap the target. Each gun, usually of 88mm calibre, could project a shell to 20,000 feet and could knock out an aircraft within 30 yards of the shell burst. However, the shrapnel from the explosion was still capable of inflicting serious damage up to 200 yards. In daylight the predictor crews followed the aircraft by telescope but at night the sound locators directed the searchlights (which had a range of 14,000 yards in clear weather). However, by night or day, the effectiveness of the flak arm in this early period was severely curtailed by clouds. III The Kammhuber Line The task of organising an efficient German night defence system was given to General Joseph Kammhuber on his release from a French prisoner of war camp in July 1940. Kammhuber rapidly secured an increase in the number of night fighters at his disposal and set up 3 zones across the main routes into Germany used by the RAF; the Zuider Zee, the Rhine estuary and west of the Ruhr. At night these zones, which were subdivided into boxes 45 kilometres by 22 kilometres (the long sides of which spanned the likely flight paths of the enemy) were forbidden to all friendly aircraft other than night fighters. The long sides of the boxes facing away from the homeland were lined with sound locators backed up by searchlights. In turn the searchlights were supported by 2 navigational beacons, one visual and one radio, which were orbited by night fighters. The tactics were that the sound locators would pick up the bomber and then direct the searchlights. As soon as they illuminated the raider the fighters would move in for the kill. This system, called Helle Nachtjagd, (illuminated night hunt) was similarly curtailed when cloud cover limited the searchlights' efficiency. It was, however, considerably improved later by the introduction into each box of a Würzburg gun-laying radar to supplement the sound locators. The Würzburgs were capable of giving height and range of aircraft and were thus more precise than the long distance Freya radars which gave early warning of the imminence of raids. Later still, Kammhuber created a complete radar system which he called Himmelbett (four poster bed). This dispensed with the searchlights but retained the beacon-orbiting night fighters. The radar arm of Himmelbett comprised a Freya to give early warning and to alert a pair of the more accurate Würzburgs, one of which was aligned on the night fighter and the other upon the intruder. Both Würzburgs were connected by land line to control posts where operators attempted to plot a course which would effect an interception between the fighter and the bomber. The Würzburg plotters, as in the case of the RAF plotters, were women (Luftwaffe Helferinnen) nicknamed Blitzmaidens by the Luftwaffe. Three of these women were attached to each Würzburg and tracked the plots on to a large translucent glass screen called a Seeburgtisch (Seeburg table). Their plots were projected on the screen as spots of light, red for the bomber and green for the fighter. Each Seeburg table covered the airspace ranged by the sector's radar and was divided into squares designated by letters of the alphabet. These squares were subdivided into smaller squares numbered from 1 to 9, each of which represented an air space of 11 by 9 kilometres. Aided by these plots the German night fighter controller's task was to direct his fighter to one of the numbered squares in which a bomber had been plotted. At that distance the intruder was likely to be within range of the night fighters' own Lichtenstein air-interception radar which had by then become available. Once the fighter was in the same square as the bomber its search would be directed by the navigator/radar operator on board. The system was later backed up with the searchlights of the Helle Nachtjagd system and by the creation of Dunkel Nachtjagd (dark night hunt) zones. While the Germans were thus strengthening their defensive system the RAF was becoming increasingly preoccupied with trying to improve its effective striking rate. The dead reckoning system of navigation which was to continue in use for the first two years of the war meant that a bomber could be as much as 20 miles off track at the estimated time of arrival at its German destination. Efforts to find the blacked-out targets when there was complete cloud cover were frequently completely unrewarded and even on clear nights the bombers were often bedevilled by German decoys in the form of random light flashes, explosions etc., released in open country. One estimate had it that between May 1940 and May 1941 49% of bombs fell in open countryside and the rest were usually scattered away from their chosen destinations in the built-up areas. When Winston Churchill was advised of the probability that only about a quarter of the bombs dropped actually reached their intended targets his comment, that if this success rate could be increased to a mere 50% it would double the bombing power without any increase in resources, was a simplistic but true summary of the situation. While the bombers were wrestling with the problem of finding their way they were also having to learn how to cope with the developing night defences. Apart from the obvious tactic of taking evasive action some pilots adopted the artifice of running their engines out of phase (de-synchronising) so as to create an irregular throbbing sound to confuse the searching sound locators, a tactic used by the Germans in the London Blitz. The device was generally disliked by the crews, however, because of the uncomfortable vibration set up in the aircraft. As one pilot put it to the author: "The trouble was, when you used the trick you had to live with it". Interestingly, the sheltering populations below, both in Germany and Britain, claimed to be able to tell "one of theirs" from "one of ours" by this characteristic sound which at the time was a chilling harbinger of destruction. However, the ploy was soon rendered ineffective with the development of radar.

IV. Improving the Hardware By the end of 1941 the picture began to brighten for Bomber Command. A new breed of heavy bombers entered service with the RAF :The Short Stirling, a four engined bomber armed with 2 .303 Browning machine guns in its nose and mid-upper turrets and four in its tail turret, and which was capable of carrying a 14,000lb bomb load; the Handley Page Halifax; the American B17 Flying Fortress; the Avro Manchester, of similar size to the Stirling but with 2 Rolls Royce Vulture engines. The Stirling was the only success initially, although it suffered from a wing span which was too short but which was dictated by the limitation imposed by the width of the RAF hangars at that time. The others did in fact develop into very effective flying machines despite their early shortcomings. In the beginning, however, the Halifax suffered from poor handling qualities and the early Fortresses did not have turrets in which to house their armament. As for the Manchester, its Vulture engines were pressed into service before they were fully developed causing many problems and earning it the nickname 'flying coffin' - a reputation which gave no inkling that it was to develop into the splendid Avro Lancaster. Also in the Autumn of 1941 a significant development in the field of aerial navigation was nearing operational readiness. This was the famous GEE box which could translate pulses issuing from 3 ground transmitting stations into strobes on a cathode ray tube in the aircraft which the navigator could further translate into fixes on the grid of lattice lines overlaid on his navigation map. GEE got its name from the first letter of the word 'grid'. The introduction of GEE into service in March 1942 meant that targets within its 400 mile range could be located, whatever the weather, within an accuracy of 2 miles. The advantages of the system were that any aircraft with the necessary receiving equipment on board could use it and, unlike the beams along which the German bombers flew to their targets, the GEE pulses were not themselves directed anywhere so that, even if detected, they would not reveal the bombers' potential destinations. Another advantage was that, as GEE did not require the navigator to issue interrogatory signals to the ground stations, the aircraft using it could not be homed upon by hostile night fighters. However, GEE was susceptible to jamming but it was to be some months before that happened. The system was later developed by the Americans into a long range version (LORAN) which had a range of 1200 miles, a version of which has survived to this day as a shipping aid. The effectiveness of the GEE device was not lost upon the Germans because in February 1944 a Junkers JU 188 reconnaissance aircraft which was forced down in this country was found to be using a captured GEE receiver and maps! Despite the accuracy of the system, or maybe because of it, the heavies were still virtually making their way to the target individually so that a raid tended to last several hours with aircraft arriving almost at random during its duration. This system was ready-made to be exploited by Kammhuber's Himmelbett system which was designed to engage single aircraft entering its radar-monitored boxes, dubbed the "Kammhuber Line" by the RAF. Mounting British losses provided grim testimony to the efficacy of the General's tactics which thrived on the steady supply of sitting ducks fed into it during the course of each evening's raid. A re-think was clearly necessary. Working on the premise that the number of bombers a Himmelbett station could handle in an hour would be limited to about half a dozen, Bomber Command reasoned that if the time taken to press home the attack could be reduced the prospective losses would also be reduced in proportion. It was, of course, the accuracy of GEE which made the change possible. The reduced likelihood of interception which would be achieved by limiting the duration of the attack had however to be measured against the increased risk of collision between unlit aircraft flying in close proximity at night. The problem was therefore passed to the Operational Research tacticians who devised the so-called 'stream' system whereby only 10 bombers would cross any given point on the route in one minute. These aircraft would not in any sense be in formation but would be randomly spread within their own time band. This compromise, while still providing the element of concentrating the force, nevertheless gave the elbow room afforded by an imaginary exclusive box in the sky of several square miles for each batch of ten aircraft. The tactic was first tried out on the 30th May 1942 in a raid on Cologne, the first of the so-called 1000 bomber raids. Codenamed 'Operation Millennium', 1046 aircraft took part in the attack which lasted just 90 minutes. The night was moonlit when losses might have been expected to be heavy under the random approach system but, in fact, the loss rate was only 3.8%. There was to be no room for complacency, however, because on the night of the 9/10th August the Germans began to jam GEE over the German mainland with their Heinrich transmitters so that the problem of delivering the bombs accurately remained. The likelihood of jamming had however been expected and the boffins were ready with anti-jamming devices which were installed in all aircraft by the 21st August 1942, which restored the effectiveness of GEE over most of its range. By this time two new aircraft had entered service with the RAF; the De Havilland Mosquito, which was designed as an unarmed light bomber with a bomb load of 2000lb. Its maximum speed (over 380 mph), its ceiling (over 30,000 ft), and its range (1000 miles), meant that it could operate over Germany by night or day with virtual impunity. A major success story, its role was to extend to photo-reconnaissance, night fighter and pathfinder. The type was to enjoy a lower loss rate than any other Bomber Command aircraft, only one being lost in the first 600 sorties flown and just ¼% lost during the whole course of the war. The other was the Avro Lancaster which evolved from the disappointing Manchester. Roy Chadwick, the designer of both aircraft, was convinced that the answer to the Manchester's shortcomings was an increased wingspan to accommodate 4 Rolls Royce Merlin engines which, although not as potentially powerful as the inadequately developed Vulture engines, were a proven operational type in the Hurricanes and Spitfires. However, as in the case of the Stirling, which also had problems associated with a restricted wingspan, the bugbear was the constraint imposed by the 100ft width of the standard RAF hangar doors. The problem was solved eventually when the Air Ministry agreed to increase the width of its hangars which enabled Chadwick to create the Lancaster with its 102ft wingspan. The need to get the Lancaster into service quickly was assisted materially by the expedient of utilising the Manchester fuselage, a significant saving in re-tooling. Like the Mosquito, the Lancaster was a major success story. Originally intended to carry a bomb load of 4000lbs, it was to be progressively adapted until it was eventually able to carry the then ultimate weapon, the 22,000lb Grand Slam bomb designed by Barnes Wallis. No other aircraft during the war could match that. In all, 7347 Lancasters were built by the time production ceased in February 1946. Total losses from all causes during the war were 3836, which represented the loss of one Lancaster for each 158 tons of bombs delivered by the type. A far more effective striking rate than any other wartime bomber. The first Lancaster sortie was a mine-laying operation (known as Gardening) in the Heligoland Bight. This was followed on the 17th April 1942 by a spectacular low level daylight raid by 12 Lancasters from 44 Squadron and 97 Squadron on the M.A.N. (Maschinen Fabrik Augsburg-Nürnberg) diesel works at Augsburg in Bavaria which was producing a large proportion of the engines for the U-boats. 7 of the 12 Lancasters were lost but the raid proved the effectiveness of the type and earned the leader of the sortie, Squadron Leader John Nettleton, the first of 10 VCs which were to be awarded to Lancaster aircrew members. Despite the addition of the 'Lanc' and the 'Mozzie' to the RAF's armoury the jamming of GEE over Germany was a setback which would have to be overcome if the RAF were to constitute a viable threat to German industry. The concept of the Pathfinder Force (PFF) was therefore mooted. The idea was that a small bomber force would proceed to the target first and mark it by flares upon which the following main force could drop its bombs. "Bomber Harris", the C in C Bomber Command, was not sold on the elitism implicit in the concept of the PFF although he did acquiesce in its formation and was responsible for the selection of its first Commander, Group Captain D.C.T.Bennett, an Australian. However, a pathfinder force is only as effective as its navigational system which meant that, in the beginning at least, the PFF was as likely to be off target as on it. Correspondingly, if they missed, everyone missed. The Luftwaffe's own bombing tactics over the United Kingdom relied upon various types of radio beams to direct their bombers to their targets. Initially they used the Knickebein beam followed in turn by the X Beams and the Y beams, all of which required the aircraft to fly along a beam which was ranged from the transmitter to target. In the case of the X Beam, a second beam transmitted from a different station bisected the main beam at the point where the bombs were to be dropped; this was the system used to carry out the devastating raid on Coventry during the night of 14/15th November 1940. The Y Beam utilized a single station which radiated a directional beam plus a ranging signal which the bomber picked up and re-transmitted to enable the ground controllers to compute the range and order the bombs to be dropped. The British scientists had not been unaware of the German developments and had been busy devising various jamming devices against them. They had also been actively engaged in seeking a foolproof British navigational system and, by the beginning of 1943, they came up with what appeared to be the answer to the Pathfinders' prayers. Codenamed OBOE, the device required two transmitting stations, one codenamed CAT which transmitted a series of dots and dashes each side of an arc which ranged over the target. The pilot had to fly along this arc guided by the dots and dashes. If he was on track he would hear a continuous note but this would break up into dots if he drifted towards the CAT transmitter or dashes if he drifted away. The other station, codenamed MOUSE, plotted the aircraft's position along the arc until it reached the point where it was instructed to release its load. The snag was that the system could only be used by one aircraft at a time but, with a range of over 250 miles from its most distant ground station and an accuracy within 100 yards, the system was tailor made for the PFF. Operationally, a small number of Mosquitoes equipped with OBOE would fly in and mark the target with flares. These would be followed by Lancasters using H2S a new centimetric wavelength radar carried by the aircraft which produced a radar 'picture' of the terrain below on a cathode ray tube. These aircraft would back up with more target indicators upon which the main force heavies directed their bombs. Targets beyond the Oboe range had to be identified by H2S alone if visual sighting was not possible. This, however, was somewhat chancy because accurate interpretation of the early H2S 'pictures' required considerable skill and there were instances where the Germans altered the 'shape' of their towns by erecting fake buildings etc. in open country. Those favouring H2S dubbed it 'Home Sweet Home'. Others, less enthusiastic, noted that H2S was the formula for hydrogen sulphide and commented laconically: 'It stinks!' The objection that "Bomber" Harris had to the formation of the PFF did not extend to the concept of pathfinding as such. It was the idea of the creation of an elitist corps and its likely effect upon the ordinary line bomber crews to which he took exception. Indeed, he felt that the idea of target marking by the best crews was sound but felt that this should be on a Group basis rather than milking the Groups to form an independent force. Harris' idea was put into practice for the first time in 5 Group by the formation of 617 Squadron at RAF Scampton to undertake the famed Dambusters Raid. This operation was conceived by Barnes Wallis (the designer of the Vickers Wellington) who reasoned that considerable damage could be done to the German war effort if a large proportion of the Ruhr industrial area were flooded by breaching some of the dams of the adjacent reservoirs. Wallis' so-called bouncing bomb (codenamed UPKEEP) which looked like an oil drum 50 inches in diameter and 60 inches long and charged with 6,600lb of RDX (an explosive 15-20% more powerful than TNT) was designed for the operation. It was carried by each of 19 specially adapted Lancasters, 9 of which were lost in the action (codenamed CHASTISE)) which took place on 16th May 1943. The bombs, which were already rotating before release, bounced along the water's surface until they struck the dam wall and rebounded. However, the backspin induced by the rotation forced them back to the wall and down to a depth of 30ft where their hydrostatic fuzes were triggered. The raid earned the VC for Wing Commander Guy Gibson who directed the others over the target by RT. (radio telephony) during the attack. This was the first use of the Master Bomber technique which was later adopted by the PFF in an effort to correct target marking errors and to eliminate the bugbear of 'creep back' where some crews dropped their loads too soon and were followed in turn by others, giving rise to a swathe of devastation in front of the intended target.

V. Electronic Warfare The development of radar by both sides was advancing with bewildering rapidity and the struggle for supremacy in this field led to considerable leapfrogging, with each side producing countermeasures to the other's innovations. The Germans' Freya early warning radars, for instance, were reinforced by the introduction of the Wassermann (Aquarius) and Mammut (Mammoth) long distance radars which could plot bombers above the radar 'horizon' as far north as Norfolk and Suffolk, but these could be jammed by the British airborne Mandrel device. British bombers were beginning to be equipped by a tail warning device called Monica but this, in turn could be homed upon by German night fighters equipped with Flensburg. Bombers could also detect when they were being monitored by the German Würzburg gun-laying radar with a device called Boozer, and German night fighters could home on working H2S sets with airborne Naxos equipment. Both sides had, however, developed independently what appeared to be the ultimate anti-radar weapon, but both were afraid to use it in case the other copied it! The British called it Window and the Germans, Düpple. The idea was incredibly simple, consisting of strips of tinfoil in various lengths and widths, some of which were backed by brown paper to give strength. Because radar relies upon echoes bouncing off the object it is scanning it could not distinguish between floating clouds of silver paper dropped by the aircraft and the aircraft themselves. The impasse was breached on the 24th July 1943 when 746 RAF bombers equipped with 40 tons of Window attacked Hamburg. The German radar operators were totally confused because the Window cloud showed up on their screens as thousands of aircraft. Accurate pinpointing of the invading bombers was therefore impossible so that, on that night, the German night defences were rendered completely ineffective. The new weapon spelled the end of the Himmelbett system because, with both the flak and night fighter arms denied radar back-up they had to rely upon random pick-ups by the similarly handicapped searchlights. As Hamburg was out of range of Oboe the PFF had to rely upon H2S alone for the raid. In consequence, because of the intrinsic difficulties with this apparatus, the plan was that 20 H2S equipped aircraft would release the first target-indicator flares. Eight follow-up aircraft were to attempt to pinpoint the target by the light of the flares and put down red target indicators. Back- up aircraft were to continue to mark the target throughout the raid. However, as in the case of all such target marking relying upon purely airborne navigation aids, there was some marking 'creep back' compounded by less experienced bomber crews, perhaps deterred by flak ahead, dropping their bombs early. In the Hamburg raid this resulted in a 7 mile carpet of incendiaries leading back from the target. On the plus side, the losses which in a raid of this nature on Hamburg would normally have been in the region of 6%, or 45 aircraft, were only 12. So 33 bombers, each with a 7 man crew, were saved by 40 tons of silver paper! With Kammhuber's defence system so comprehensively thwarted, Goering gave the go-ahead for Major Hajo Herrmann, a former bomber pilot, to try out his proposal that single-engined aircraft should be used as night fighters. His system, called Wilde Sau (Wild Boar), required 50 'free lance' Messerschmitt Me 109s to patrol the target area above the pre-arranged flak burst height of 15,000ft. They were to rely upon the fireglow from the bombers' targets or, when the sky was overcast, the reflection from searchlight beams upon the clouds below (nicknamed Mattscheibe, or focusing screen) to silhouette the bombers. If weather conditions did not provide sufficient illumination below, the Wild Boars were to drop parachute flares from above the stream. With the advent of Window the twin engined fighters of the Himmelbett system were also forced to seek other means of locating their prey. The answer emerged as the Zahme Sau (Tame Boar) system which was devised by Oberst Viktor von Lossburg. At the outset of the raid the twin-engined Tame Boars were scrambled and directed from radio beacon to radio beacon until they arrived in the area where the greatest concentration of Window was. When they reached the target area the twin-engined fighters located their prey either with their airborne Lichtenstein radar, which could home on a bomber from a range of 3 miles, or visually using the light of the Mattscheibe fireglow or the flares being used by the single-engined Wild Boars. The very nature of the Tame Boar scheme meant that these aircraft ranged at considerable distances from their home bases so that their sorties were often concluded by touch-down at airfields other than their own. The success of the new German tactics was reflected in the increased Bomber Command losses which were approaching the calculated acceptable rate of 200 per month. As the life expectancy of bomber crews in mid 1943 was only 11 operations at best and 8 on average, considerable thought had to be given to denying the night fighters access to the stream as long as possible. Thus came into use a jamming device called TINSEL. This was, in essence, a microphone placed in an engine nacelle on the bomber to pick up engine noise which the bomber's radio operator then transmitted on the frequencies used by the German night fighter controllers. Another tactic was the use of Mosquito aircraft to mount diversionary or 'spoof' raids in order to attract the night fighters towards them and a hostile reception rather than the more vulnerable main force heavies. As Tinsel, and its later version, Special Tinsel, were ineffective against the VHF (Very High Frequency) transmissions which the Germans began to use for night fighter control the British brought into use a device called ABC (Airborne Cigar). This apparatus was fitted into aircraft of 101 Squadron which was based at Ludford Magna in Lincolnshire and whose Lancasters were adapted to accommodate an extra German-speaking crew member to operate it. This Squadron continued to fly as part of the main force and carried a bomb load which was reduced by 1000lbs to allow for the weight of the extra man and his equipment. During the raid the special operator listened for the night fighter controller's radio telephone transmissions in order to jam them with his three ABC transmitters. Those operators with the necessary degree of fluency could also inject false instructions into the German system and thus cause further confusion. One at least of these special operators was of German origin and had living relatives in Germany. He was therefore given an English name and false British identity papers in case he was shot down. The protection afforded the main stream by this measure was not enjoyed by 101 Squadron because they went on to earn the unenviable distinction of losing more aircrew than any other bomber squadron during the war - 1094 men in all. As the effect of ABC began to bite on the German night fighter control system the Germans had to seek help elsewhere - particularly in view of the vulnerability of a visual system to adverse weather conditions. They therefore brought into use two new pieces of ground equipment, NAXOS and KORFU, which were able to produce fixes on the H2S being used by the PFF which by then headed every attack. As the Mosquitoes which were engaged in spoof attacks did not carry H2S the new equipment enabled the Germans to distinguish between the main force and the spoofers early in the night's proceedings by keeping tabs on the PFF heavies. Another development which was to cause considerable dismay to bomber crews was the arming of the German night fighters with 2 additional 20mm cannons aimed obliquely upwards and forwards which were sighted by an extra reflector sight above the pilot's head. The device, dubbed Schrägemusik (slanted music) by the Luftwaffe, was regarded as something of a secret weapon when it was introduced during the latter half of 1943. It enabled the attacking fighters to approach the bombers from underneath where they would be unseen and where the bombers were most vulnerable. As the guns did not use tracer bullets scores of aircraft were shot down without their crews being aware of what had beset them. To put this development into perspective it should be borne in mind that 90% of the bombers completed their sorties without coming into contact with night fighters at all. However, of the 10% who were intercepted, half were shot down - usually without returning fire. Indeed, war-time German pilots observed that 4/5ths of bombers shot down did not open fire or take evasive action before being attacked and that 2/5ths did not do so after being attacked, which suggests a certain lack of vigilance on the part of some bomber crews. The price of a safe return by the bombers was therefore constant sweeping searches of the night sky by alert gunners because, if an attacker were spotted in time, they could instruct the pilot to take violent evasive action called corkscrewing which would deprive the attacker of a steady aim and frequently cause him to break off the engagement and seek a softer target with less vigilant gunners. The Lancaster was the most effective bomber at corkscrewing because it could endure the most violent of manoeuvres without structural damage. This was just as well because it was less able to withstand actual battle damage than the more robust Halifax. The Autumn of 1943 witnessed the replacement of General Kammhuber by General-Major Schmid and the advent of a new German airborne radar to exploit the Tame Boar system. This was SN2 which was impervious to the Window then in use. Its maximum range of 4 miles put it outside the ambit of Boozer and Monica but, as its minimum range was 400 yds (too long for visual night interception), it had to be used in conjunction with the earlier Lichtenstein. This, together with Naxos 2 (an airborne version of the German ground H2S locator) and Flensburg which homed on the bombers' Monica fighter-warning device, were to cause the bombers considerable problems. The German flak arm was also being strengthened by increasing the size of the 88 mm light batteries from 4 guns to 8. In addition, to guard the more important targets, Grossbatterien (large batteries) comprising 2 or 3 of the enlarged single batteries were created. Each battery, large or small, was controlled by a single predictor which meant that up to 18 guns might engage one bomber at a time. The firepower was also increased by bringing into service higher calibre guns including a 105mm weapon and, the largest of all, a massive 125mm calibre gun. In view of the constant demands of the German army for front line troops many of the flak crews included elderly men and schoolboys. However, flak as a weapon was becoming a very expensive deterrent because by the end of 1944 it was costing about 33,500 rounds for each aircraft downed compared to the 4057 rounds required in 1942. The flak batteries were also sometimes ordered to launch various false target indicators over open country in order to deceive the bombers into dropping their cargoes where they could do no harm. An interesting sidelight to this is that British aircrew believed that the German gunners were also discharging a particular type of cascading flare called the Scarecrow intended to simulate a blazing bomber falling to earth and thus put fear into the hearts of the bomber crews. After the war the Germans denied ever trying such a tactic so it is likely that the crews were seeing actual bombers on fire and were comforted by a piece of British propaganda or that the flares were an experimental German anti-aircraft shell which discharged incendiary pellets destined for the bombers' fuel tanks which were designed to seal themselves if struck by ordinary shrapnel. On the British side the Mk3 H2S sets with higher definition came into use, some of which were fitted with Fishpond which extended the usefulness of the equipment by enabling the wireless operators to scan beneath the aircraft for approaching fighters armed with Schrägemusik. '"Bomber" Harris' idea of strengthening each Group's own target marking capacity was furthered by the introduction of G-H, a two station radio direction-finding (RDF) system that was the reverse of Oboe in that an instrument in the aircraft tracked it over the target by measurement from one station, and determined its bomb release point by its distance from the other. Unlike Oboe, which was really an aid for target marking aircraft, G-H could be employed by up to 80 aircraft from one pair of stations and thus could be used for direct bombing without the aid of markers. Another bonus was that multiple targets could be attacked at the same time. The device was first used practically during a raid on the Mannesmann steel works at Düsseldorf on night of 3/4th November 1943. For their part, the Germans were countering the efforts of 101 Squadron's German-speaking ABC special operators by using females to relay the fighter controllers' instructions to the night fighters. The British responded by transmitting German-speaking female voices from the powerful GPO ground transmitter in Rugby (codenamed CORONA). The Germans were therefore forced to switch channels frequently; a minor irritant but useful in that it caused some delay in the fighters reaching the main stream, with a consequent reduction in RAF casualties. However, when fighters and bombers did meet up, particularly on moonlit nights when the bombers' vapour trails could be seen, the consequences for the raiders could be dire. For example, between November 1943 and the end of March 1944 1047 aircraft were lost and 1682 were damaged in the course of the 35 major raids during the period. The worst losses of all were sustained during long haul raids deep into Germany on targets such as Nuremberg on 30th March 1944 when 94 were lost out of the 795 which took part.

VI. Invasion! With the Allies' invasion imminent the RAF was switched to short range targets in France and the Low Countries while the Americans continued their daylight raids deep into Germany with overwhelming fighter cover, the object being to down as many German fighters as possible prior to the invasion. Indeed, in the first 4 months of 1944 the Luftwaffe lost more than 1000 pilots. This was, in part, due to the fact that the defending German fighters with the heavy weaponry they were forced to carry to combat the American heavy bombers were slower than the bombers' escorts. Bomber Command was actively involved in the run up to the D-Day landings and was called in to attack German coastal defences, but for each raid launched upon the prospective landing sites two were made elsewhere along the coast to disguise Allied intentions. However, during the night of 5/6th June 1944 prior to the landings 1,136 Halifaxes and Lancasters led by Oboe equipped Mosquitoes dropped 5267 tons of high explosive bombs on the coastal batteries where the landings were to take place. The results of their efforts can still be seen today along the Normandy coastline where huge slabs of concrete are scattered like discarded toys many yards away from the emplacements where they were built. Following the invasion on 6th June 1944, a determined effort was made to cut the Germans' fuel supplies. The RAF therefore returned to the 'Happy Valley' to attack the synthetic oil processing plants in the Ruhr while the Americans switched their daylight raids to the oil refineries in south Germany, Austria, Hungary and Rumania. In the case of the small benzol plants in the Ruhr only 3 Group using G-H could find and hit them in almost any weather. The Group was also called-in in December that year when Field Marshal von Rundstedt counter-attacked the Allies through the Ardennes. Owing to the adverse weather over the UK and Europe only 3 Group was able to respond to General Eisenhower's request for tactical air support for his armies. 3 Group's efforts, which included the bombing of the completely fogbound town of Trier (the centre of concentration for German armour and supplies), won them instant praise from the General for 'achieving the impossible'. VII Confound and Destroy Despite the diversion of the D-Day landings the toll being exacted upon Bomber Command by the Luftwaffe was reaching the point of unacceptability. Fortunately, a solution was at hand. Late in 1943 Air Vice Marshal Addison, an RAF signals officer in charge of 80 Wing an Electronic Countermeasures (ECM) Unit which had been set up to jam the German Knickebein, X and Y beams, was ordered to form 100 Group to co-ordinate all the ECM efforts to protect the main force from the depredations of the night fighters. The Group's motto 'Confound and Destroy', was an apt description for Addison's aspirations for his command. His tactics were threefold:- i) To employ Mosquitoes as intruders to engage enemy night fighters ii) To provide main force radar jamming cover - supplementing 101 Squadron's efforts in that direction. iii) To create diversionary raids with small numbers of heavies dropping Window to create a picture on the German radar screens of much larger numbers of aircraft headed in a direction other than that proposed for the main force. The Mosquitoes were equipped with Serrate and Perfectos radars. The first of these could home on the German night fighters' bomber-detection Lichtenstein radar and the other on to their IFF (Identification Friend or Foe) equipment, the signals from which were supposed to let their own side know who they were. In the course of a raid the Mosquitoes would either be covering the flanks of the main force or orbiting the German night fighter beacons. Although these Mosquitoes did not destroy as many German aircraft as the American daylight escorts they had a devastating effect upon the morale of the German night fighter crews who attributed every night aircraft loss to the type. They were even prepared to risk attack by their own flak by switching off their IFF sets . The radar jamming cover was provided by pairs of Flying Fortresses and Liberators crewed by RAF personnel of 214 and 223 Squadrons flying in front of, with and behind the main stream; usually 1000ft or so above the planned height of the raid. These aircraft also carried a special radio operator (sometimes two) to provide jamming cover from before the arrival of the PFF until the last main force heavy was clear of the target. Jamming devices included the strangely named JOSTLE, DINA and PIPERACK. Spoofing undertaken by the Group involved 20 or so Fortresses and/or Liberators dropping Window at a set rate on a course towards a target different from that of the main force in order to attract the night fighters towards themselves rather than the mainstream bombers. During the Group's most active period from mid 1944 until the end of the war a typical night raid would begin with Halifaxes, and sometimes Stirlings with trainee crews, patrolling in front of the prospective routes into France, Belgium or Holland using their Mandrel equipment to screen the impending raid from the probing eye of the German long range Freya radars. The first intimation the Germans would have of a raid was therefore when either the main force or the spoofers broke through the screen. They would then be faced with the problem of trying to distinguish between the two. To confuse the issue further the spoofers would on occasion even drop target indicators at the end of their spoofing run. The efforts of 100 Group reduced significantly the main force losses and although it was expected that the spoofers, in particular, would suffer heavily in their prima-facie sacrificial role their percentage losses were no more than average. This was no doubt attributable to their comparatively smaller numbers. An interesting sidelight to the role of 223 Squadron is that when it was formed in August 1944 the role envisaged for its Liberators was to jam the beams which were thought to be controlling the V2 rockets which the Germans were launching on London. The Liberators were therefore sent on patrols along the Dutch coast watching for the tell-tale vapour trail of a rocket rising over Europe so that the special operator on board could try to pick up its controlling signal and jam it. However, as the V2s were not radio controlled, these patrols (codenamed BIG BEN) were abandoned and 223 Squadron joined the Fortresses of 214 Squadron in shielding the main stream. VIII Counting the Cost As the Allied attacks on the German aviation spirit production units began to take effect the search for alternative fuels brought into service two new German aircraft types; the rocket-propelled Messerschmitt Me 163 which had a top speed of over 596 mph and a ceiling of over 50,000ft, and the twin-engined Me 262 turbo-jet with a top speed of 540mph which used diesel fuel. The rocket-propelled Me 163 had a powered flight of only 8 minutes and therefore had to be directed very precisely to its target by running commentary, after which it had to break off the action and glide back to its base. In its gliding mode it was of course very vulnerable to escorting fighters. The Me 262 had a much longer duration and, apart from its superiority over the bombers, was able to counter the Mosquito threat, particularly those employed on the 'Milk Run' - nuisance night sorties mounted over Berlin to activate the German air raid sirens and the Civil Defence organisation. By this time, however, the war was nearing its end so the potential of these aircraft was not fully realised, but one would have hoped that the developing British Meteor and Vampire jets would have countered the new developments. Despite the crippling fuel shortage, the Luftwaffe was able to mount Operation Gisela on 3rd March 1945 when 100 Junkers Ju88 and Heinkel He219 night fighters followed the main force back and attacked 27 airfields in UK as the returning bombers prepared to land at their bases. Out of 48 RAF planes attacked 22 were shot down and 8 more were damaged at a cost to the Luftwaffe of 6 aircraft. The tactic was tried again a fortnight later on a smaller scale but only one aircraft was destroyed - an RAF plane on a training flight. This was the last offensive action by the Luftwaffe in World War 2. The RAF's last sortie was launched against enemy shipping at Kiel on the 3rd May 1945. It brought the total of sorties launched against Germany, the Occupied Territories and Italy to 389,809. Of these sorties, 336,037 were bombing raids (during which a total of 955,044 tons of bombs were dropped) and 19,025 were sea mining missions (during which a total of 47,307 mines were laid). The remainder were made up of fighter support, meteorological flights, intruder attacks upon night fighter bases, reconnaissance flights, agent dropping, radio countermeasures and spoof raids. Of the 126,000 Bomber Command aircrew who took part in the battle 44% did not return............. Copyright H.C Sykes 1989

Title	Author	Publisher
Bomber Command.		Air Ministry.1941
Special Operations (No 101 Squadron)	Raymond Alexander	101 Sqdn. Association
The Dambusters.	Paul Brickhill.	1972 Evans Brothers Ltd.
Famous Bombers of the Second World War.	William Green.	1979 McDonald and Janes.
Bomber County.	T.N. Hancock.	1978 Lincs. Library Service.
Most Secret War.	R.V. Jones.	1978 Hamish Hamilton
The Secret War	Brian Johnson.	1978 BBC
RAF Bomber Units. July 1942 - 1945.	Bryan Philpott.	1978 Osprey Publishing.
Battle Over The Reich.	Alfred Price.	1973 Ian Allan Ltd.
Bomber Harris.	Dudley Saward.	1984 Cassel.
Confound and Destroy.	Martin Streetly.	1978 McDonald and Janes. H.C.S. 1989