If the German air forces faced problems in the autumn and winter of 1940, they were as nothing compared with the problems facing their enemy. The success against German daylight operations in September accelerated the German transition to night-bombing. Against night-time attack there was still in the autumn of 1940 almost no effective defence. As long as bombers flew well clear of the ceiling of anti-aircraft fire and searchlights, or chose routes with poor anti-aircraft defences, the only factor inhibiting the impact of a raid was the difficulty of getting bombs sufficiently concentrated on the chosen objectives. Otherwise the bomber always got through. The problems of defence against night attack had been fully appreciated in Britain after the outbreak of war, and a committee was established in March 1940 to consider its implications, but the pressure of daylight fighting throughout the first nine months of 1940 left night defence as a low priority. The switch to extensive night-bombing in September 1940 provoked an immediate crisis. There were very few dedicated night-fighter squadrons and the evidence from daylight attacks showed how few aircraft could be brought down by anti-aircraft fire. When Dowding was made to account for the poor state of night defences at a meeting in the Air Ministry on 18 October 1940, he confirmed that his force had been trying for a year to intercept enemy aircraft at night ‘with negligible success’.143
One answer was to expand the fixed anti-aircraft defences. The balloon barrage was extended and balloons were painted black. Plans were made to arm balloon cables with an explosive device, but production was slow and success unpredictable.144 In September the anti-aircraft artillery was reorganized into three regional commands (Southern, Midland and Northern) to give it greater flexibility, but the supply of guns was still far short of what was regarded as adequate to defend all vital targets in the three areas. Out of 100 designated priority zones only 60 were defended and some of those with only a handful of guns.145 Although the importance of radar-controlled gun-laying was recognized, the GL MkI apparatus introduced in increasing numbers during the bombing campaign was not capable of accurate height prediction and proved difficult to use. There were still only 10 per cent of the required sets available by February 1941. Nor were the searchlight batteries served with effective radar equipment as they were later in the war; even by June 1941, when the bombing was almost over, Sir Frederick Pile, commander-in-chief of Anti-Aircraft Command, still had only 54 out of the promised 2,000 Search Light Control sets (known as ‘Elsie’) available.146 A more sophisticated gun-laying equipment, GL MkII, arrived in small quantities from January but was difficult to operate except by highly skilled personnel. It came into its own only in 1942. Many of the anti-aircraft gun sites were not easily accessible and conditions for the crews amounted in many cases in 1940 to little more than a bunker dug out of the ground, prone to flooding and poor protection from the deafening sound of the guns. Anti-aircraft troops were low priority during the period of invasion scare, and many of those who manned guns against German raiders had come straight from training camp. So short of personnel was the Command that in 1941 Pile insisted on recruiting women to work at gun sites, but enrolment did not start until after the end of the bombing, in August 1941. The women, Churchill was assured, would have to be educated and ‘preferably golf and tennis players’.147
Over the course of the bombing from July 1940 to June 1941, anti-aircraft artillery was relatively ineffective. It was claimed that 170 aircraft were shot down at night over the whole course of the campaign and perhaps 118 damaged, but precise verification was difficult and the temptation to claim success in a gruelling and noisy battle hard to resist. For this result it proved necessary to fire prodigious quantities of ammunition. Scientists brought in to advise the Air Ministry found that in autumn 1940 more than 6,000 shells were fired for every aircraft claimed, and even by April 1941 the number had only been reduced to 3,195. They regarded the idea of a ‘barrage’ as an illusion, since only ‘aimed fire’ had any chance of success, as with all artillery.148 Yet in response to criticism that there was too little anti-aircraft fire during the first great raids on London, Pile ordered the 92 guns in the Inner Artillery Zone on 7 September 1940 increased to 203 in 48 hours and asked every unit to fire everything it could, regardless of results. In September 260,000 shells were fired. Although it was discovered that civilian morale was boosted by the noisy activity, civilians were exposed to a rain of shrapnel and the danger of unexploded shells, while gun barrels wore out faster than they could be replaced from new production. In November guns were shifted away from London towards the Midlands, to meet demands from industry for more effective protection, but the game of musical chairs simply exposed the fact that there was not enough artillery to go round. The Command was forced to cut back on firing and ordered searchlights to be extinguished, despite popular protest, because it was realized that with too few guns and lights, the target areas were easily distinguishable for enemy pilots as the ones defended. The blackout proved more effective than the lights in confusing the raiders but was in the end no substitute for an extensive belt across the country of radar-guided searchlights and guns. Fixed anti-aircraft defences, in the absence of effective radar equipment, were, as Pile later admitted in his memoirs, deficient.
Greater reliance came to be placed on decoy sites, known as Special Fire (SF) or ‘Starfish’, which were constructed during the last few months of 1940 in country areas around key targets. By November, 27 sites had been constructed and 5 more were in preparation. To reassure the rural population there were orders to ensure that no decoy was closer than 500 yards to any inhabited building, or closer than 800 yards to a village, though in reality these distances gave scant protection.149 Raised tanks filled with a mixture of creosote, diesel oil or paraffin surrounded troughs filled with straw set out in the shape of a star. When the troughs were filled and set alight, the effect replicated the white and yellow blaze from incendiary bombs. Bristol, for example, was surrounded by 12 starfish sites, some almost 20 miles distant. The first became operational on Blackdown, in the Mendip Hills, in late November 1940 and a week later attracted its first bombs. In January over 1,000 incendiaries fell on the site. A decoy airfield laid out in fields near Uphill, on the outskirts of Weston-super-Mare, was attacked heavily the same month after it had been ignited by hand with matches and a bottle of petrol because the electric switch failed in heavy rain. Some 42 high-explosive bombs and 1,500 incendiaries fell during the raid. A nearby farmer found his herd of dairy cattle dead or mutilated, some still struggling to walk with their legs blown off.150 During the rest of 1941 the Starfish were ignited 70 times, with mixed results; in some cases three-quarters of the bombs were dropped on the decoy site, in others none at all.151
Camouflage was another way of concealing the target, but the Camouflage Advisory Panel set up in 1939 and the Camouflage Policy Committee established in March 1940 both reached conclusions that camouflage was difficult to apply effectively and worked best only for daytime raids. Some effort went into providing steel-covered netting to mask the shadow of large buildings and painting trees and shrubs on hangars and storerooms, but it was concluded that heavy industrial haze, persistent fogs and an effective blackout served much the same purpose as camouflage. Plans to paint sections of railway line dark green to blend with the surrounding fields were rejected on the grounds that pilots would never be fooled by it, while the extensive use of paint on key buildings provoked a sudden scare that German agents would somehow find a way of adding their own patches of special chemically enhanced paint intended to make the targets visible to German infra-red equipment.152 More attention was given to the idea that light-coloured concrete roads and runways could be covered with tarmac and coloured chippings to mask the glare, but the expense was considerable and the government refused to sanction road camouflage when local councils applied for funding.153 In summer 1940 the Camouflage Committee stopped meeting.
Some of the solutions suggested by scientists brought in to advise the air force and the government were equa
lly far-fetched. One idea was to lay a minefield in the sky in the path of oncoming bombers, on the same principle as a minefield at sea. The object was to attach a small one-pound explosive with a self-detonating mechanism to a long length of piano wire, with a parachute at one end. A line of mines would be laid from an aircraft at right angles to the approaching enemy and as the mines sank at a carefully calibrated speed they were supposed to land on the aircraft wings and explode. Dowding reluctantly agreed to tests in the summer of 1940 but unsurprisingly they proved disappointing.154 At some point in October 1940 Churchill’s personal scientific adviser, Frederick Lindemann, was converted to the idea of the long aerial mine and persuaded the prime minister to endorse it. Orders were placed for 1 million mines and 24 mine-laying aircraft, but the scheme was always overambitious, since it relied on very precise knowledge of where enemy aircraft would be flying and on perfect timing. It was discovered that the first 1,000 mines delivered all had defective self-detonating devices. When efforts were made in June 1941 to lay the first minefields, only three attempts were made, without any observable success. The scheme was quietly scrapped.155 Lindemann was also the source of a second fanciful countermeasure. In November 1939 he suggested exploring the use of colloidal coal (a finely ground and treated coal dust) to cover rivers, canals and ports with a non-reflective film to frustrate their use as navigation markers on moonlit nights. Experiments continued throughout the bombing campaign but it was found that winds and tidal waters drove the dust to the edge of the water, making the estuaries or canals more rather than less visible. After two years of experiment a public exercise was conducted in February 1942 on the Thames between Westminster and Vauxhall bridges. Tons of dust was sprayed from converted barges; it gradually gathered at the river’s edge and after two hours sank.156
It was generally recognized that the only effective way to be sure of destroying an enemy bomber was night-time interception by a dedicated night-fighter aircraft, but it proved beyond the capability of the RAF to achieve this for almost the whole of the German bombing campaign. The problem was regarded as so critical that on 14 September 1940 a committee was set up under the retired Air Chief Marshal Sir John Salmond to investigate the whole issue of night-fighter policy. Three days later the committee presented its findings, recommending a special night-fighter staff, a night-fighting training unit, the decentralization of control over night-fighters to increase speed of response and flexibility, and the introduction of effective radar aids. Great expectations were had of the transfer of a number of single-engine fighter squadrons to night work on clear moonlit nights.157 Dowding opposed almost all of the recommendations and paid for his resistance with his command. On 1 October he attended a meeting of the Salmon committee where he explained that reorganizing his force would achieve nothing without effective airborne radar (AI = Airborne Interception), which was the only prospect for success. A week later he met Churchill and reiterated his view that the recommended changes would achieve little.158 He was made to accept the proposed changes with reluctance and on 9 October ordered the activation of nine night-fighter squadrons, six of them in 11 Group in south-east England, including a number of converted Hurricane fighters. On 4 November he was told to introduce more Hurricanes to try to stem the new flow of bombing towards the Midlands, but he told the Air Ministry that without radar detection these efforts constituted nothing more than ‘wishful flying’.159
It has been argued that the knives were already out for Dowding even before the crisis over night-fighting erupted in October 1940. A secret memorandum circulated in September claiming, among other things, that Dowding had ‘a very slow brain’, reached Churchill’s close colleague Brendan Bracken.160 Dowding was certainly not widely popular but did enjoy the backing of Churchill and the chief of the air staff, Sir Cyril Newall, with whom he had worked closely to mould the air defence system in the 1930s. Dowding’s stubborn insistence that there was nothing very effective he could do about night-interception until the technology was ready was used against him, particularly by Churchill’s friend Lord Beaverbrook, appointed Minister of Aircraft Production in May 1940, whose angry claims that aircraft production was facing a calamity as a result of bombing played an important part in the campaign to get Dowding finally retired. When Beaverbrook asked for aircraft squadrons to be stationed next to aircraft factories to afford them protection from night attack, Dowding refused. Dowding offered more anti-aircraft guns, but in October 1940 there were only 158 guns defending the entire aircraft industry, from Scotland to southern England.161 By then opinion in the Air Ministry had hardened against him. On 2 October Air Chief Marshal Newall, his firmest ally, was forced to retire, to be replaced by Air Marshal Charles Portal, who remained chief-of-staff down to the end of the war.162 A few days later Salmond wrote to Churchill insisting that Dowding should step down at once, and that all the senior commanders in the air force agreed.163 Dowding’s testy response to the effort to expand night defences in October must have convinced even Churchill that it was time for him to go. On 13 November Dowding was notified that he was to be succeeded by Air Vice Marshal Sholto Douglas, who was one of his many critics in the ministry. Dowding was the most senior casualty of the German bomber offensive.
Sholto Douglas tried immediately to demonstrate that he was more willing than his predecessor to find a way to challenge the German night offensive, but he soon found that Dowding’s reservations had been justified. Douglas requested a minimum of 20 night-fighter squadrons, including 8 squadrons of Hurricanes, but by March 1941 he still had only 5 squadrons, while the introduction of the Beaufighter Mark II (now designated the principal night-fighter) and of Airborne Interception (AI-Mark IV) radar for night-time operations was much slower than required. In December 1940 Portal rejected Douglas’s request for further expansion of the night force with the argument that there was not a single crew capable of regularly shooting down night-bombers. He allocated Beaufighter production to the war at sea.164 The figures for night-fighter interception made it evident that Portal, and before him Dowding, were right. In the raids against Birmingham in mid-November 1940 there were 100 British aircraft airborne but only one German casualty, a victim of accident. Only a handful of bombers were shot down before the advent of the more effective AI-Mark IV radar sets in March 1941, almost at the end of the campaign. In January 1941 the RAF needed 198 sorties for every German aircraft shot down, but in March the figure fell dramatically to 47. During 1941 the night defences claimed a total of 435 German planes, but 357 of them from April onwards.165 In January 1941 the first 6 inland Ground Control Interception (GCI) radars for tracking a single fighter on to an incoming bomber became operational, but they were faced with regular teething troubles and only began to work as planned by the summer, when 17 static and mobile stations were available out of a planned network of 150.166 As with so much of the British response to the German campaign, improved operational and technical effectiveness came only after the bombing was almost over.
Only in the spring of 1941 did tactical instructions to German bomber units begin to take the threat of British night-fighters seriously The danger that British fighters might try to use the German radio beams to guide them to the bombers led to instructions to make irregular zigzag courses to confuse the enemy, to approach on a broad front, rather than grouped together, to fly at lower heights or, in some cases, to employ single aircraft to fly in very low at 200–300 metres.167 In July 1941 it was finally admitted that German tactics would have to change to cope with the mounting evidence that RAF night-fighters could track incoming aircraft and find them over the target. Bomber units were instructed to mount decoy flights with weak forces on widely distant targets to shield the true destination of the main attacking force (a tactic soon adopted by the RAF over Germany). The main force was instructed to attack on a very broad front, flying from numerous different directions towards the chief objective, particularly on clear and moonlit nights, even though the effect of this and other tactical changes was to
disperse German bomb attacks even more and to reduce the prospect of a heavy, concentrated blow.168
The exposure of Britain’s cities and industries to heavy bomb attack with feeble defences provoked widespread anxiety in Whitehall. For much of the bombing campaign, the size of the German force continued to be greatly exaggerated. Air intelligence estimated that on 1 November 1940 the German Air Force had 1,800 bombers and 1,900 single-engine and twin-engine fighters, when the true figures for late October, unknown in London, were 833 serviceable bombers and 829 serviceable fighters.169 When Churchill was told in December that the German Air Force was two and a half times larger than the RAF, he asked for the figures to be investigated. Understanding the size of the German force was, he thought, ‘of capital importance to the whole future picture of the war’.170 Lindemann discovered that air intelligence had been assuming a figure of 12 aircraft for each German squadron, plus reserves, when the available intercept intelligence suggested only 9 per squadron, with a reserve of 3. In January 1941 he was able to demonstrate that the German bomber force had 1,200 aircraft, which was closer to the reality than any previous estimates, and a better reflection of the actual impact German bombing was making.171
Churchill nevertheless remained apprehensive about German intentions. He expected the German Air Force to make a ‘far more serious attempt’ in the spring and early summer of 1941 to defeat Britain from the air. Intelligence from a Swiss source suggested that Germany had been conserving thousands of aircraft for a single supreme blow, an ‘air banquet’, to be mounted in the spring for a genuine knockout blow from the air and, improbable though this was, Churchill asked the air staff how many aircraft Britain could reply with if a banquet was prepared with every available plane. He was told by a sceptical Portal in the spring of 1941 that Germany could probably send 14,000 planes, but the RAF could retaliate with only a feeble 6,500, including 2,000 trainers and 3,000 reserves.172 Churchill was just as anxious about the possibility of an overpowerful German Air Force resorting to gas to finish the war quickly. In November 1940 he asked his de facto deputy, the Labour Party leader, Clement Attlee, to make sure that British stocks of poison gas reached at least 2,000 tons of available chemicals; the air staff informed Churchill that existing gas supplies could be used for four or five days of concentrated gas attack on German cities, or for two weeks if gas and high explosive were dropped together.173 Concern over the supply of gas bombs had already arisen in the summer of 1940 when it was evident that there were not enough containers for the gas. Beaverbrook was instructed to accelerate production of gas bombs and spray canisters for mustard gas for the moment, as Sinclair put it, ‘when gas warfare commences’, and by October he could promise to meet the air staff requirement for a minimum of 200,000 gas bombs. By the spring of 1941, in anticipation of a more extensive and deadly bombing campaign in the winter of 1941–2, the RAF was primed to conduct a gas war against the German homeland.174
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