The Bombing War: Europe 1939–1945

by Richard Overy

  Through all the arguments about German strategy during July 1940 the one consistent thread was the importance of the German Air Force as the key instrument for creating the possibility of British defeat. This reality pampered air force pretensions. A later wartime account of the summer of 1940 by the air force history office underlined the novelty of a situation in which the air force could now undertake the ‘strategic offensive … on its own and independent of the other services’.42 A paper prepared by the commander of Fliegerkorps I in July opened with the defiant assertion that Germany was by definition an ‘air power’ whereas Britain was a sea power: ‘Its chief weapon against England is the Air Force, then the Navy, followed by the landing forces and the Army.’43 Extensive intelligence on British targets had been gathered by the air force before the outbreak of war in case it should ever be needed. On 1 June 1939 the German Air Ministry had published a comprehensive volume on British air forces, anti-aircraft defences, war economic targets and flying conditions. Orientation Book Great Britain provided exceptionally detailed maps of British airbases, support depots and anti-aircraft defences. The maps of key economic targets included grain silos, oil storage tanks, the aircraft industry, the armaments industry, raw material production, iron ore fields, steelworks and aluminium plants. The graphs of cloud-cover frequency varied from an average of 40 to 50 per cent across the year over Croydon in the south to between 65 and 85 per cent over Tynemouth in the north.44 A second gazetteer of the economic geography and meteorological pattern of the British Isles was available from 1938 and reissued in February 1940. Its 100 pages supplied a wealth of detailed information about every major city and port, including photographs of the dock areas and calculations of average wind speeds and direction over the course of a typical year. The climatic information painted a gloomy picture for a possible strategic air war. ‘All in all,’ concluded the document, ‘it appears that the British Isles, particularly in the winter months of frequent storms, fog and dense cloud, present very difficult meteorological flying conditions, which without doubt belong among the most unpleasant to be found in any of those major countries regarded as civilised [Kulturländer].’45

  Even before any decisions had been taken at Hitler’s headquarters, the air force ordered training operations over targets in southern England using small numbers of aircraft, or sometimes only a single plane. Significantly these flights, known generally by the German term Störangriffe (nuisance raids), were undertaken both by day and by night to prepare German bomber pilots for raids of either kind. Some involved mining operations off the English coast. The so-called ‘schooling flights’ were intended to familiarize crews with the target areas, the pattern of enemy anti-aircraft defences, and the variety of routes available to attack a particular objective, so that when the real offensive was ordered there would be a greater prospect of operational success. Crews sent on the raids were told to alter the timings continually in order to confuse the defenders.46 The British side found it difficult to understand what the object of the German intruders could be, since the bombs were scattered widely over often quite insubstantial targets. On one night bombs were distributed almost entirely on open country in Cornwall, Devon, Somerset, Gloucestershire, Shropshire and South Wales (where a lucky hit struck Monmouth railway station).47 It was finally assumed by the RAF that the attacks were practice runs, testing the water before a larger campaign, as indeed they were.

  The German Air Force drew some important lessons from the schooling, particularly about night-time attacks, which in contrast to the conventional image of German bombing during the Battle of Britain, were in the majority, even during July and August. In the London Borough of Balham, for example, there were eight small raids in the last week of August, two by day and six by night. In the first week of September, before the onset of the heavy bombing of the capital, there were ten more raids, seven of them at night, operations designed to help train crews with the more difficult task of navigating in the dark.48 It was discovered that aircraft carried too few bombs of the right calibre to be sure of hitting anything successfully; rather than a small number of heavy high-explosive bombs, bomber units were told to carry larger numbers of smaller bombs to make it more likely that some of the bombs would hit their target. The same lesson was learned with incendiary bombs. It was realized that they had to smother an area in large numbers to be sure of creating fires difficult to extinguish. These changes determined the tactics to be used throughout the campaign that followed.49

  While the air force prepared with enthusiasm for its first independent campaign, the planners at Hitler’s headquarters moved to clip its wings. The operational directives that eventually emerged during the course of July were based on the experience gained in Poland and the Western campaign. The aerial assault on England differed from the earlier operations only because, rather than operating simultaneously, the air force would have to attack first, followed after a short time by the army. Though the geography presented different challenges, the campaign plan differed little from the successful pattern of combined operations established in the first year of war. The air force was to provide an aerial umbrella over the invasion force and powerful artillery support for the army as it landed. Rather than undertake an independent campaign, the whole air force was expected to facilitate the operation of surface forces.50 On 21 July Göring met the three air fleet commanders to discuss the operational planning, and three days later the following ‘Tasks and Goals’ for the air force were distributed to air force units reflecting these tactical priorities:

  (1) Fighting for air supremacy, that is to say smashing the enemy air force and its sources of power, in particular the engine-industry

  (2) protection for the army crossing and the paratrooper operations through:

  a) fight against the enemy fleet

  b) fight against attacking enemy air force

  c) direct support for the army

  (3) reduction of England through paralysing its harbour installations. Destruction of its stocks and obstruction of imports.51

  The fighter arm was needed first, to destroy enemy fighters before they could inflict damage on German bombers. Once air superiority was achieved, bombers would be free to attack targets beyond the range of fighter protection, which extended little further than London, and to attack round the clock, by day and by night. The object was to move forward, stage by stage across southern England to a line from King’s Lynn to Leicester, destroying air force, military and economic targets systematically.52

  For the crews impatiently waiting at airfields across northern Europe, the critical factor was when the assault would start. The order to stand by at full readiness had been sent out on 17 July 1940, but there was still no D-Day. Uncertainty existed at every level about whether the operation would really go ahead. Secret police reports on the mood of the population found a growing impatience with the postponement of ‘the great attack on England’, even more so as RAF bombers flew almost nightly to targets in north-west Germany, forcing millions of people into air-raid shelters and cellars.53 Hitler’s air force adjutant, von Below, observed that even Göring was unsure that an air campaign would be really necessary. ‘We did not know what plan to evolve,’ Göring complained to an interrogator at Nuremberg six years later. ‘I did not know whether there would be an invasion or not, or what would be undertaken.’54 Finally, in late July Göring was told to have his forces ready for action, so that when Hitler ordered the air assault it could start at 12 hours’ notice, but no date was fixed.55 Operational plans were finally put into the form of a directive from Hitler’s headquarters only on 1 August, a reflection of Hitler’s own hesitancy about the wisdom of the invasion and his growing preoccupation with Russia. The date for the start of the air assault, codenamed ‘Eagle Day’ (Adlertag), was fixed for 5 August, Britain’s grim weather permitting. A separate note from Supreme Headquarters indicated that Hitler would decide whether Sea Lion would go ahead between 8 and 15 days after the start of the air campaign. T
he deciding factor was the success of the air force.56 The concern with the weather had not been misplaced. Weather conditions were to play a critical part throughout the whole of the subsequent campaign, placing arbitrary limits on German action. During the first days of August large-scale air operations were impossible. On 6 August Göring summoned his air fleet commanders to his country estate at Carinhall, where they finalized the plan to destroy the RAF in four days, both its fighter arm and its bomber force, just as they had done in Poland and France. ‘Eagle Day’ was postponed until 10 August, then for a further three days. In Berlin, workmen could be seen building stands decorated with giant eagles and monumental replicas of an iron cross around the Brandenburg Gate, the backdrop, so it was rumoured, to the anticipated victory parade over Britain.57

  THE ‘ENGLAND-ATTACK’

  The long aerial campaign that began in earnest in August 1940 has always been divided in British accounts into two distinct parts, the Battle of Britain, from July to October 1940, and the ‘Blitz’, from September 1940 to May 1941. The distinction owes something to the fact that they were fought by two different forces, the Battle largely by RAF Fighter Command, the Blitz by the civil defence forces, anti-aircraft units and small numbers of RAF night-fighters. There were also differences of geography: the Battle was fought over southern England, the Blitz across the whole of the British Isles. Looked at from the German perspective the conflict has an entirely different shape. The German Air Force fought a campaign almost a year long, from July 1940 to June 1941. It was almost always called the ‘England-War’ or the ‘England-Attack’, and it was treated on the German side as a unity because it was conducted by the same air forces, flying operations from the same bases by day or by night, though increasingly the latter, with the aim of weakening British resistance, perhaps decisively. Accounts by the German Air Force history office written in 1943 and 1944 describe the phases of a ten- or eleven-month bombing campaign. German airmen were dismissive of the idea that there was a distinct ‘Battle of Britain’, though they were familiar with the term; throughout the war they preferred to talk about ‘England’ because of its distinct cultural resonance in Germany.58 When public announcements were made of British bombing attacks, it was common to talk of the English ‘Gentlemen’ who had authorized them – polite, hypocritical and ruthless.

  The two forces that opposed each other in August 1940 were organized, equipped and led very differently. On 3 August the German Air Force had a bomber strength of 1,438 aircraft of which 949 were serviceable, substantially fewer than in May; to conduct the war against the RAF there were 878 serviceable Messerschmitt Me109E/F single-engine fighters and 320 Messerschmitt Me110C twin-engine fighters from an operational strength of 1,065 and 414 respectively.59 The Ju87B dive-bomber, which had proved so effective in the land campaign, was withdrawn after the opening days of the ‘England-Attack’ when it was discovered that its slow speed in the dive made it exceptionally vulnerable to fast fighter interception. The aircraft were divided between the three air fleets: 44 combat squadrons (19 bomber) in Air Fleet 2; 33 combat squadrons (14 bomber) in Air Fleet 3; and six combat squadrons (four bomber) in Air Fleet 5.60 Unlike the British and American systems, the German Air Force was not organized functionally but territorially. Bombers, fighters, fighter-bombers and reconnaissance aircraft were under a single air fleet commander responsible for a particular geographical area. Air Fleet 2 was led by Albert Kesselring (former commander of Air Fleet 1), a jovial former cavalry officer, who had joined the air force in 1934, served briefly as air force chief of staff in the mid-1930s, and eventually rose to be commander-in-chief of Axis forces in the Mediterranean theatre, where his authorization of savage reprisals earned him the status of a war criminal in 1945, after the end of the war. His fellow commander of Air Fleet 3, Hugo Sperrle, like Kesselring a Bavarian and former army officer, boasted a commandingly large frame that dwarfed even the corpulent Göring. Air Fleet 5, stationed in Norway under General Stumpff, was the Cinderella of the air force. Short of aircraft, faced with dauntingly difficult and lengthy flights across the North Sea, Stumpff’s force played a marginal part in the campaign.

  Over them all presided Hermann Göring, both Air Minister and air force commander-in-chief, promoted to Reich Marshal in July 1940, the highest-ranking officer in the German armed forces. He was served by an Air Force General Staff which had liaison officers posted to Hitler’s Supreme Headquarters to maintain regular contact. Most of the running of the air force was conducted by the general staff and the permanent officials in the Air Ministry, whose state secretary was the former Lufthansa director Erhard Milch, also recently created field marshal. The special political position enjoyed by their commander-in-chief, who was president of the German Parliament and Hitler’s nominated successor as Führer, meant that Göring could argue the air force case from a position of considerable strength, though it also meant that his time and fluctuating energy had to be divided among a great many tasks.61 He was a jealous and ambitious commander, almost childishly enthusiastic about the air force, yet almost all accounts of his leadership highlight the arbitrary, irregular and often ill-informed character of his interventions. One of the first American interrogators assigned to Göring in 1945 summed up the prevailing view among his subordinates, culled from the many interviews he had read: ‘Lazy, superficial, arrogant, vain and above all a bon viveur.’62 In practice he was a more assiduous and perceptive commander than this judgement suggests, but he did manipulate the air force to enhance his own standing. The role of the air force in the strategic bombing of Britain owed much to Göring’s conviction that it could achieve things the other services could not. The political value of success for both the air force and its leader was a driving force of the strategic campaign.

  The bomber arm, which would bear the brunt of the eleven-month campaign, was equipped with three aircraft types: two of them, the Dornier Do17Z and the Heinkel He111H/P, had first been developed in 1934–5 and were now nearing obsolescence. They were relatively slow, poorly armed and could carry over most of the distances required between 2,200 and 4,000 lbs of bombs; the third was the more recently developed medium bomber, the Junkers Ju88A, which first saw service on any scale in August 1940 and soon became the principal bomber model as the Do17 and He111 were gradually phased out. The Ju88 had been welcomed in the late 1930s as a versatile and effective aircraft, also capable of a reconnaissance and night-fighter role, but it was plagued with development problems and only in the autumn of 1940 did it start to appear in quantity.63 But instead of the promised speed and enhanced striking power, the Junkers bomber, like the ones it was designed to replace, carried a modest defensive armament, flew at around 280 miles per hour and could carry little more than the existing aircraft, around 4,000 lbs of bombs, with even smaller weights for longer flights.64 Confidence that the Ju88 would fulfil all immediate requirements meant that there was no heavy bomber available in 1940, though they were in the pipeline. The Heinkel He177 multi-engine long-range bomber commissioned in 1938 was still in an early development stage, which left nothing except for the slow Focke-Wulf Fw200 ‘Condor’, a converted airliner that was used to good effect in the early stages of the war against shipping, but was far too vulnerable to risk in overland attacks. The small German bombers also carried relatively small bombs, principally the 50-kg or 250-kg fragmentation bomb, with a high charge-to-weight ratio, the 1,000-kg landmine, and the 1-kg incendiary bomb, packed in cases of 36 bombs each. Loaded with thermite (a mixture of ferrous oxide and powdered aluminium), and with a casing of magnesium alloy, the incendiary core burned for around a minute, the casing for twelve to fifteen minutes.65

  The bombers enjoyed the benefit of sophisticated methods of electronic navigation developed in Germany in the 1930s. The Knickebein (crooked leg) system, pioneered by the German Telefunken company, used two beams of radio pulses sent from separate transmitters. One sent Morse dashes, one dots. When the two merged, the aircraft was at the point to release the bombs.
The beams were based on the Lorenz blind-landing equipment developed in the 1930s to guide aircraft back to an airfield at night or in poor weather. The second system, known as X-Gerät (Equipment X), was more complex. It utilized six Lorenz beams, three pointing at the target, three designed to cross them at intervals, the first 50 kilometres away from the objective, the second 5 kilometres away and the third just before the actual target zone. A timer activated on the aircraft automatically released the bombs at precisely the pre-calculated distance. In November 1940 Y-Gerät was added using just a single beam, which relied on signals sent back from the bomber to calculate its range. When the ground station was satisfied that the aircraft was precisely over the target, it transmitted an automatic bomb release.66 The Knickebein method could be used in any bomber with blind-landing equipment, the X- and Y-Gerät only by specially converted aircraft. Experimental training began in 1938, and in late summer 1939, before the invasion of Poland, the new units were established as Kampfgruppe 100, Bomber Group for Special Operations, directly under Göring’s control.67 It was found that both systems could achieve a remarkable level of accuracy under the right conditions, in marked contrast to the poor navigational prospects for the RAF. Around 30 to 40 Heinkel 111s fitted with the new equipment were used to undertake pinpoint attacks or to act as a vanguard for a larger force by dropping flares and incendiaries in the target area. In the spring of 1941 a second unit was activated, Kampfgruppe 26, designed to use the Y-Gerät. Transmitter stations were set up from Stavangar in Norway to Cherbourg in western France, a total of seven by the summer of 1941.68