The Blitz (English: 'lightning') was a bombing campaign by Nazi Germany and Fascist Italy against the United Kingdom during the Second World War. It lasted for eight months, from 7 September 1940 to 16 May 1941. The name is a shortened form of Blitzkrieg, a term used in the popular press to describe a German style of surprise attack used during the war. Toward the end of the Battle of Britain in 1940, daylight air superiority over the United Kingdom was contested between the Luftwaffe and the Royal Air Force. Germany began conducting mass air attacks against British cities, beginning with London, in an attempt to draw the RAF Fighter Command into a battle of annihilation. Adolf Hitler and Reichsmarschall Hermann Göring, commander-in-chief of the Luftwaffe, ordered the new policy on 6 September 1940. From 7 September 1940, London was systematically bombed by the Luftwaffe for 56 of the following 57 days and nights. The attacks included a large daylight attack against London on 15 September, a large raid on 29 December 1940 against London resulting in a firestorm known as the Second Great Fire of London, and a large raid on the night of 10–11 May 1941. The Luftwaffe gradually decreased daylight operations in favour of night attacks to evade attacks by the RAF, and the Blitz became a night bombing campaign after October 1940. The Luftwaffe attacked the main Atlantic seaport of Liverpool in the Liverpool Blitz. The North Sea port of Hull, a convenient and easily found target or secondary target for bombers unable to locate their primary targets, suffered the Hull Blitz. The port cities of Bristol, Cardiff, Portsmouth, Plymouth, Southampton, Sunderland, Swansea, Belfast and Glasgow also were bombed, as were the industrial centres of Birmingham, Coventry, Manchester and Sheffield. More than 40,000 civilians were killed by Luftwaffe bombing during the war, almost half of them in the capital, where more than a million houses were destroyed or damaged. In early July 1940, the German High Command began planning Operation Barbarossa, the invasion of the Soviet Union. Bombing failed to demoralise the British into surrender or do much damage to the war economy; eight months of bombing never seriously hampered British war production, which continued to increase. The greatest effect was to force the British to disperse the production of aircraft and spare parts. British wartime studies concluded that most cities took 10 to 15 days to recover when hit severely, although some, such as Birmingham, took three months. The German air offensive and regime change operation failed because the Luftwaffe High Command (Oberkommando der Luftwaffe, OKL) did not develop a methodical strategy for destroying British war industry. Poor intelligence about British industry and economic efficiency led to the OKL concentrating on tactics, rather than strategy. The bombing effort was diluted by attacks against several sets of industries instead of constant pressure on those most vital to the British war effort.
Background information
Luftwaffe and strategic bombing
In the 1920s and 1930s airpower theorists such as Giulio Douhet and Billy Mitchell claimed that air forces could win wars, obviating the need for land and sea combat. It was thought that "the bomber will always get through", and could not be resisted, particularly at night. Industry, seats of government and communications could be destroyed, depriving an opponent of the means to make war. Bombing civilians would cause a collapse of morale, and a loss of production in the remaining factories. Democracies, where public opinion was allowed, were thought particularly vulnerable. The Royal Air Force (RAF) and the United States Army Air Corps (USAAC) adopted much of this apocalyptic thinking. The policy of RAF Bomber Command became an attempt to achieve victory through the destruction of civilian will, communications and industry. The Luftwaffe took a cautious view of strategic bombing, but the OKL did not oppose the strategic bombardment of industries or cities. It believed it could greatly affect the balance of power on the battlefield by disrupting production and damaging civilian morale. OKL did not believe air power alone could be decisive, and the Luftwaffe did not adopt an official policy of the deliberate bombing of civilians until 1942. The vital industries and transport centres that would be targeted for shutdown were valid military targets. It could be claimed civilians were not to be targeted directly, but the breakdown of production would affect their morale and will to fight. German legal scholars of the 1930s carefully worked out guidelines for what type of bombing was permissible under international law. While direct attacks against civilians were ruled out as "terror bombing", the concept of attacking vital war industries—and probable heavy civilian casualties and breakdown of civilian morale—was ruled as acceptable. From the beginning of the Nazi regime until 1939, there was a debate in German military journals over the role of strategic bombardment, with some contributors arguing along the lines of the British and Americans. General Walther Wever (Chief of the Luftwaffe General Staff 1 March 1935 – 3 June 1936) championed strategic bombing, and the building of suitable aircraft, although he emphasised the importance of aviation in operational and tactical terms. Wever outlined five points of air strategy:
To destroy the enemy air force by bombing its bases and aircraft factories, and defeat enemy air forces that attacked German targets. To prevent the movement of large enemy ground forces to the decisive areas, by destroying railways and roads, particularly bridges and tunnels, which are indispensable for the movement and supply of forces To support the operations of the army formations, independent of railways, i.e., armoured forces and motorised forces, by impeding the enemy's advance, and participating directly in ground operations. To support naval operations by attacking naval bases, protecting German naval bases and participating directly in naval battles To paralyse the enemy armed forces, by stopping production in armaments factories. Wever argued that OKL should not be solely educated in tactical and operational matters, but also in grand strategy, war economics, armament production, and the mentality of potential opponents (also known as intelligence analysis). Wever's vision was not realised, staff studies in those subjects fell by the wayside, and the Air Academies focused on tactics, technology and operational planning, rather than on independent strategic air offensives. In 1936 Wever died in an air crash, and the failure to implement his vision for the new Luftwaffe was largely attributable to his successors. Ex-army personnel, and his successors as Chief of the Luftwaffe General Staff, Albert Kesselring (3 June 1936 – 31 May 1937) and Hans-Jürgen Stumpff (1 June 1937 – 31 January 1939), are usually blamed for abandoning strategic planning for close air support. Two prominent enthusiasts for ground-support operations (direct or indirect) were Hugo Sperrle, the commander of Luftflotte 3 (1 February 1939 – 23 August 1944), and Hans Jeschonnek, Chief of the Luftwaffe General Staff (1 February 1939 – 19 August 1943). The Luftwaffe was not pressed into ground support operations, either because of pressure from the army, or because it was led by ex-soldiers; indeed, the Luftwaffe favoured a model of joint inter-service operations, rather than independent strategic air campaigns.
Hitler, Göring, and air power
Hitler paid less attention to the bombing of opponents than to air defence, although he promoted the development of a bomber force in the 1930s, and understood it was possible to use bombers for strategic purposes. He told OKL in 1939 that ruthless employment of the Luftwaffe against the heart of the British will to resist, would follow when the moment was right. Hitler quickly developed scepticism toward strategic bombing, confirmed by the results of the Blitz. He frequently complained of the Luftwaffe's inability to damage industries sufficiently, saying, "The munitions industry cannot be impeded effectively by air raids ... usually, the prescribed targets are not hit". While the war was being planned, Hitler never insisted upon the Luftwaffe planning a strategic bombing campaign, and did not even give ample warning to the air staff that war with Britain (or even Russia) was a possibility. The amount of firm operational and tactical preparation for a bombing campaign was minimal, largely because of the failure by Hitler, as supreme commander, to insist upon such a commitment. Ultimately, Hitler was trapped within his own vision of bombing as a terror weapon (formed in the 1930s when he threatened smaller nations into accepting German rule, rather than suffering air bombardment). This had important implications. It showed the extent to which Hitler mistook Allied strategy for one of morale breaking, instead of one of economic warfare—and any damage to morale as a bonus. Hitler was much more attracted to the political aspects of bombing. As the mere threat of it had produced diplomatic results in the 1930s, he expected that the threat of German retaliation would persuade the Allies to adopt a policy of moderation, and not to begin a policy of unrestricted bombing. His hope was—for reasons of political prestige within Germany itself—that the German population would be protected from the Allied bombings. When this proved impossible, he began to fear that popular feeling would turn against his regime, and redoubled efforts to mount a similar "terror offensive" against Britain, in order to produce a stalemate, in which both sides would hesitate to use bombing at all. A major problem in the management of the Luftwaffe was Göring. Hitler believed the Luftwaffe was "the most effective strategic weapon", and in reply to repeated requests from the Kriegsmarine, for control over naval aircraft, he insisted, "We should never have been able to hold our own in this war, if we had not had an undivided Luftwaffe". Such principles made it much harder to integrate the air force into the overall strategy and produced in Göring a jealous and damaging defense of his "empire" while removing Hitler voluntarily from the systematic direction of the Luftwaffe at either the strategic or operational level. When Hitler tried to intervene more in the running of the air force later in the war, he was faced with a political conflict of his own making, between himself and Göring, which was not fully resolved until the war was almost over. In 1940 and 1941, Göring's refusal to co-operate with the Kriegsmarine denied the entire Wehrmacht military forces of the Reich the chance to strangle British sea communications, which might have had a strategic, or decisive, effect in the war against the British Empire. The deliberate separation of the Luftwaffe from the rest of the military structure encouraged the emergence of a major "communications gap" between Hitler and the Luftwaffe; other factors helped to exacerbate this. For one thing, Göring's fear of Hitler led him to falsify or misrepresent what information was available in the direction of an uncritical and over-optimistic interpretation of air strength. When Göring decided against continuing Wever's original heavy bomber programme, in 1937, the Reichsmarschall's own explanation was that Hitler wanted to know only how many bombers there were, and not how many engines each had. In July 1939 Göring arranged a display of the Luftwaffe's most advanced equipment at Rechlin, to give the impression the air force was more prepared for a strategic air war than was actually the case.
Battle of Britain
Although not specifically prepared to conduct independent strategic air operations against an opponent, the Luftwaffe was expected to do this over Britain. From July until September 1940 the Luftwaffe attacked Fighter Command, to gain air superiority as a prelude to invasion. This involved the bombing of English Channel convoys, ports, and RAF airfields and supporting industries. Destroying RAF Fighter Command was thought to allow the Germans control of the skies over the invasion area. It was supposed Bomber Command, Coastal Command, and the Royal Navy could not operate under conditions of German air superiority. The weakness of the Luftwaffe's intelligence meant that their aircraft were too often unable to locate their targets, so that attacks on factories and airfields failed to achieve the desired results. British fighter aircraft production continued at a rate surpassing Germany's, during the Battle of Britain, by 2 to 1. The British produced 10,000 aircraft in 1940, in comparison to Germany's 8,000. The replacement of pilots and aircrew was more difficult. Both the RAF and Luftwaffe struggled to replace manpower losses (though the Germans had larger reserves of trained aircrew). The circumstances hampered the Germans more than the British: Operating over home territory, British aircrew could fly again, if they survived being shot down. German crews (even if they survived) faced capture. Moreover, the Reich's bombers carried four to five crew, representing a greater loss of manpower. On 7 September the Germans shifted away from the destruction of the RAF's supporting structures. German intelligence suggested Fighter Command was weakening, and that an attack on London would force it into a final battle of annihilation, while compelling the British Government into surrender. The decision to change strategy is sometimes claimed to have been a major mistake by OKL, argued that persisting with attacks on RAF airfields might have won air superiority for the Luftwaffe. Others argue that the Luftwaffe made little impression on Fighter Command, in the last week of August and first week of September, and that the shift in strategy was not decisive. It also has been argued that it was doubtful the Luftwaffe could have won air superiority, before the "weather window" began to deteriorate (in October). It also was possible, if RAF losses became severe, that they could pull out to the north, wait for the German invasion, then redeploy southward again. Other historians argue that the outcome of the air battle was irrelevant; the massive numerical superiority of British naval forces and the inherent weakness of the Kriegsmarine would have made the projected German invasion, Unternehmen Seelöwe (Operation Sea Lion), a disaster, with or without German air superiority.
=== Change in strategy === Regardless of the ability of the Luftwaffe to win air superiority, Hitler was frustrated by its slow advance. With no sign of the RAF weakening, and the Luftflotten suffering many losses, OKL was keen for a change in strategy. To reduce losses further, strategy changed to prefer night raids, darkness offering the bombers greater protection. It was decided to focus on bombing Britain's industrial cities, in daylight, to begin with. The main focus was London. The first major raid took place on 7 September. On 15 September, on a date known as Battle of Britain Day, a large-scale raid was launched in daylight, but suffered significant loss without any lasting gain. Although there were a few large air battles fought in daylight, later in the month and into October, the Luftwaffe switched its main effort to night attacks, official policy starting 7 October. The air campaign against London and other British cities soon got underway. However, the Luftwaffe faced limitations. Its aircraft—Dornier Do 17, Junkers Ju 88 and Heinkel He 111s—were capable of carrying out strategic missions but the damage they were capable of doing was limited due to their small bomb loads. The Luftwaffe's decision, in the interwar period, to concentrate on medium bombers can be attributed to several reasons:
Hitler did not intend or foresee a war with Britain in 1939. The OKL believed a medium bomber could carry out strategic missions just as well as a heavy bomber force. Germany did not possess the resources, nor technical ability, to produce four-engined bombers, before the war. Although it had equipment capable of doing serious damage, the Luftwaffe also had an unclear strategy, and poor intelligence. The OKL had not been informed that Britain was to be considered a potential opponent, until early 1938; it had too little time to gather reliable intelligence on Britain's industries. Moreover, the OKL could not settle on an appropriate strategy. German planners had to decide whether the Luftwaffe should deliver the weight of its attacks against a specific segment of British industry (such as aircraft factories), or against a system of interrelated industries (such as Britain's import and distribution network—or even in a blow aimed at breaking the morale of the British population. The Luftwaffe's strategy became increasingly aimless, over the winter of 1940–1941. Disputes among OKL staff revolved more around tactics, than strategy. This lack of clarity condemned the offensive over Britain to failure, well before it had begun. In an operational capacity, limitations in weapons technology, and quick British reactions, were making it more difficult to achieve strategic effect. Attacking ports, shipping and imports, as well as disrupting rail traffic in the surrounding areas (especially the distribution of coal, an important fuel in all industrial economies of the Second World War) would net a positive result. However, the use of delayed-action bombs, while initially very effective, gradually had less impact, partly because they failed to detonate. The British had anticipated the change in strategy and dispersed its production facilities, making them less vulnerable to a concentrated attack. Regional commissioners were given plenipotentiary powers to restore communications, and to organise the distribution of supplies to keep the war economy moving.
Civil defence
Pre-war preparations and fears
London had nine million people—a fifth of the British population—living in an area of 750 square miles (1,940 square kilometres), which was difficult to defend because of its size. Based on experience with German strategic bombing during World War I against the United Kingdom, the British government estimated that 50 casualties—with about one-third killed—would result for every tonne of bombs dropped on London. The estimate of tonnes of bombs an enemy could drop per day grew as aircraft technology advanced, from 75 in 1922, to 150 in 1934, to 644 in 1937. In 1937, the Committee on Imperial Defence estimated that an attack of 60 days would result in 600,000 dead and 1.2 million wounded. News reports of the Spanish Civil War, such as the bombing of Barcelona, supported the 50-casualties-per-tonne estimate. By 1938, experts generally expected that Germany would try to drop as much as 3,500 tonnes in the first 24 hours of war and average 700 tonnes a day for several weeks. In addition to high-explosive and incendiary bombs, the Germans could use poison gas and even bacteriological warfare, all with a high degree of accuracy. In 1939, the military theoretician B. H. Liddell Hart predicted that 250,000 deaths and injuries in Britain could occur in the first week of war. London hospitals prepared for 300,000 casualties in the first week of war. British air raid sirens sounded for the first time, 22 minutes after Neville Chamberlain declared war on Germany. Although bombing attacks unexpectedly did not begin immediately during the Phoney War, civilians were aware of the deadly power of aerial attacks through newsreels of Barcelona, the Bombing of Guernica and the Bombing of Shanghai. Many popular works of fiction during the 1920s and 1930s portrayed aerial bombing, such as H. G. Wells' novel The Shape of Things to Come and its 1936 film adaptation, and others such as The Air War of 1936 and The Poison War. Harold Macmillan wrote in 1956 that he and others around him "thought of air warfare in 1938 rather as people think of nuclear war today". Based in part on the experience of German bombing in the First World War, politicians feared mass psychological trauma from aerial attacks and the collapse of civil society. In 1938, a committee of psychiatrists predicted three times as many mental as physical casualties from aerial bombing, implying three to four million psychiatric patients. Winston Churchill, as a backbencher, told Parliament in 1934, "We must expect that, under the pressure of continuous attack upon London, at least three or four million people would be driven out into the open country around the metropolis". Panic during the Munich crisis, such as the migration by 150,000 people to Wales, contributed to fear of social chaos. The government planned the evacuation of four million people—mostly women and children—from urban areas, including 1.4 million from London. It expected about 90% of evacuees to stay in private homes, conducted an extensive survey to determine the amount of space available and made detailed preparations for transporting evacuees. A trial blackout was held on 10 August 1939 and when Germany invaded Poland on 1 September, a blackout began at sunset. Lights were not allowed after dark for almost six years, and the blackout became by far the most unpopular aspect of the war for civilians, even more than rationing. The relocation of the government and the civil service was also planned but would only have occurred if necessary so as not to damage civilian morale. Not only was there evacuation over land, but also by ship. The Children's Overseas Reception Board was organised by the government to help parents send their children overseas to four British Dominions—Canada, Australia, New Zealand, and South Africa. The programme evacuated 2,664 boys and girls (ages 5–15) until its ending in October after the sinking of the SS City of Benares with the loss of 81 children out of 100 on board. Much civil defence preparation in the form of shelters was left in the hands of local authorities and many areas such as Birmingham, Coventry, Belfast and the East End of London did not have enough shelters. The unexpected delay to civilian bombing during the Phoney War meant that the shelter programme finished in June 1940, before the Blitz. The programme favoured back garden Anderson shelters and small brick surface shelters. Many of the latter were abandoned in 1940 as unsafe. Authorities expected that the raids would be brief and in daylight, rather than attacks by night, which forced Londoners to sleep in shelters.
Communal shelters
Deep shelters provided most protection against a direct hit. The government did not build them for large populations before the war because of cost, time to build and fears that their safety would cause occupants to refuse to leave to return to work or that anti-war sentiment would develop in large congregations of civilians. The government saw the leading role taken by the Communist Party of Great Britain in advocating the building of deep shelters as an attempt to damage civilian morale, especially after the Molotov–Ribbentrop Pact of August 1939. The most important existing communal shelters were the London Underground stations. Although many civilians had used them for shelter during the First World War, the government in 1939 refused to allow the stations to be used as shelters so as not to interfere with commuter and troop travel and the fears that occupants might refuse to leave. Underground officials were ordered to lock station entrances during raids but by the second week of heavy bombing, the government relented and ordered the stations to be opened. Each day orderly lines of people queued until 4:00 pm, when they were allowed to enter the stations. In mid-September 1940, about 150,000 people a night slept in the Underground, although by winter and spring the numbers declined to 100,000 or less. Battle noises were muffled and sleep was easier in the deepest stations, but many people were killed from direct hits on stations. In March 1943, 173 men, women and children were crushed to death at Bethnal Green tube station in a crowd surge after a woman fell down the steps as she entered the station. A single direct hit on a shelter in Stoke Newington in October 1940 killed 160 civilians.
Communal shelters never housed more than one seventh of Greater London residents. Peak use of the Underground as shelter was 177,000 on 27 September 1940 and a November 1940 census of London found that about 4% of residents used the Tube and other large shelters, 9% in public surface shelters and 27% in private home shelters, implying that the remaining 60% of the city stayed at home. The government distributed Anderson shelters until 1941 and that year began distributing the Morrison shelter, which could be used inside homes. Public demand caused the government in October 1940 to build new deep shelters within the Underground to hold 80,000 people but the period of heaviest bombing had passed before they were finished. By the end of 1940 improvements had been made in the Underground and in many other large shelters. Authorities provided stoves and bathrooms and canteen trains provided food. Tickets were issued for bunks in large shelters, to reduce the amount of time spent queuing. Committees quickly formed within shelters as informal governments, and organisations such as the British Red Cross and the Salvation Army worked to improve conditions. Entertainment included concerts, films, plays and books from local libraries. Although only a small number of Londoners used the mass shelters, when journalists, celebrities and foreigners visited they became part of the Beveridge Report, part of a national debate on social and class division. Most residents found that such divisions continued within the shelters and many arguments and fights occurred over noise, space and other matters. Anti-Jewish sentiment was reported, particularly around the East End of London, with antisemitic graffiti and antisemitic rumours, such as that Jewish people were "hogging" air raid shelters. Contrary to pre-war fears of antisemitic violence in the East End, one observer found that the "Cockney and the Jew [worked] together, against the Indian".
=== "Blitz Spirit" === Although the intensity of the bombing was not as great as pre-war expectations, thus making an equal comparison impossible, no psychiatric crisis occurred because of the Blitz even during the period of greatest bombing of September 1940. An American witness wrote, "By every test and measure I am able to apply, these people are staunch to the bone and won't quit ... the British are stronger and in a better position than they were at its beginning". People referred to raids as if they were weather, stating that a day was "very blitzy".
According to Anna Freud and Edward Glover, London civilians surprisingly did not suffer from widespread shell shock, unlike the soldiers in the Dunkirk evacuation. The psychoanalysts were correct, and the special network of psychiatric clinics opened to receive mental casualties of the attacks closed due to lack of need. Although the stress of the war resulted in many anxiety attacks, eating disorders, fatigue, weeping, miscarriages, and other physical and mental ailments, society did not collapse. The number of suicides and drunkenness declined, and London recorded only about two cases of "bomb neurosis" per week in the first three months of bombing. Many civilians found that the best way to retain mental stability was to be with family, and after the first few weeks of bombing, avoidance of the evacuation programmes grew. The cheerful crowds visiting bomb sites were so large they interfered with rescue work. Pub visits increased in number (beer was never rationed), and 13,000 attended cricket at Lord's Cricket Ground. People left shelters when told instead of refusing to leave, although many housewives reportedly enjoyed the break from housework. Some people even told government surveyors that they enjoyed air raids if they occurred occasionally, perhaps once a week. Despite the aerial attacks, defeat in Norway and France, and the threat of invasion, overall morale remained high. A poll by Gallup found only 3% of Britons expected to lose the war in May 1940. Another poll found an 88% approval rating for Churchill in July. A third poll found 89% support for his leadership in October. Support for peace negotiations declined from 29% in February. Each setback caused more civilians to volunteer to become unpaid Local Defence Volunteers, later known as the Home Guard. Workers worked longer shifts and over weekends. Contributions rose to the £5,000 "Spitfire Funds" to build fighters and the number of work days lost to strikes in 1940 was the lowest in history.
=== Civilian mobilisation === Civilians of London played an enormous role in protecting their city. Many civilians who were unwilling or unable to join the military joined the Home Guard, the Air Raid Precautions service (ARP), the Auxiliary Fire Service, and many other civilian organisations. The AFS had 138,000 personnel by July 1939. Only one year earlier, there had only been 6,600 full-time and 13,800 part-time firemen in the entire country. Before the war, civilians were issued with 50 million respirators (gas masks) in case bombardment with gas began before evacuation. During the Blitz, The Scout Association guided fire engines to where they were most needed and became known as the "Blitz Scouts". Many unemployed people were drafted into the Army Pay Corps; and, together with the Pioneer Corps, were tasked with salvaging and clean-up. The Women's Voluntary Services for Civil Defence (WVS) was established in 1938 by the Home Secretary, Samuel Hoare, who considered it the female branch of the ARP. The WVS organised the evacuation of children, established centres for those displaced by bombing and operated canteens, salvage and recycling schemes. By the end of 1941, the WVS had one million members. Pre-war dire predictions of mass air-raid neurosis were not borne out. Predictions had underestimated civilian adaptability and resourcefulness. There were also many new civil defence roles that gave a sense of fighting back rather than despair. Official histories concluded that the mental health of the nation may have actually improved, while panic was rare.
Pre-war RAF night defence
British air doctrine, since Hugh Trenchard had commanded the Royal Flying Corps (1915–1917), stressed offence as the best means of defence, which became known as the cult of the offensive. To prevent German formations from hitting targets in Britain, Bomber Command would destroy Luftwaffe aircraft on their bases, aircraft in their factories and fuel reserves by attacking oil plants. This philosophy proved impractical, as Bomber Command lacked the technology and equipment for mass night operations, since resources were diverted to Fighter Command in the mid-1930s and it took until 1943 to catch up. Dowding agreed air defence would require some offensive action and that fighters could not defend Britain alone. Until September 1939, the RAF lacked specialist night-fighting aircraft and relied on anti-aircraft units, which were poorly equipped and lacking in numbers. The attitude of the Air Ministry was in contrast to the experiences of the First World War when German bombers caused physical and psychological damage out of all proportion to their numbers. Around 250 tons (9,000 bombs) had been dropped, killing 1,413 people and injuring 3,500 more. Many people over 35 remembered the bombing and were afraid of more. From 1916 to 1918, German raids had diminished against countermeasures which demonstrated defence against night air raids was possible. Although night air defence was causing greater concern before the war, it was not at the forefront of RAF planning after 1935, when funds were directed into the new ground-based radar day fighter interception system. The difficulty of RAF bombers in night navigation and target finding led the British to believe that it would be the same for German bomber crews. There was also a mentality in all air forces that flying by day would obviate the need for night operations and their inherent disadvantages. Hugh Dowding, Air Officer Commanding Fighter Command, defeated the Luftwaffe in the Battle of Britain, but preparing day fighter defences left little for night air defence. When the Luftwaffe struck at British cities for the first time on 7 September 1940, a number of civic and political leaders were worried by Dowding's apparent lack of reaction to the new crisis. Dowding accepted that as AOC, he was responsible for the day and night defence of Britain but seemed reluctant to act quickly and his critics in the Air Staff felt that this was due to his stubborn nature. Dowding was summoned on 17 October, to explain the poor state of the night defences and the supposed (but ultimately successful) "failure" of his daytime strategy. The Minister of Aircraft Production, Lord Beaverbrook and Churchill distanced themselves. The failure to prepare adequate night air defences was undeniable but it was not the responsibility of the AOC Fighter Command to dictate the disposal of resources. The general neglect of the RAF until the late spurt in 1938, left few resources for night air defence and the Government, through the Air Ministry and other civil and military institutions was responsible for policy. Before the war, the Chamberlain government stated that night defence from air attack should not take up much of the national effort.
Technology
German night navigation devices
Because of the inaccuracy of celestial navigation for night navigation and target finding in a fast-moving aircraft, the Luftwaffe developed radio navigation devices and relied on three systems: Knickebein (Crooked Leg), X-Gerät (X-Device), and Y-Gerät (Y-Device). This led the British to develop countermeasures, which became known as the Battle of the Beams. Bomber crews already had some experience with the Lorenz beam, a commercial blind-landing aid for night or bad weather landings. The Germans adapted the short-range Lorenz system into Knickebein, a 30–33 MHz system, which used two Lorenz beams with much stronger signals. Two aerials at ground stations were rotated so that their beams converged over the target. The German bombers would fly along either beam until they picked up the signal from the other beam. When a continuous sound was heard from the second beam the crew knew they were above the target and dropped their bombs. Knickebein was in general use but the X-Gerät was reserved for specially trained pathfinder crews. X-Gerät receivers were mounted in He 111s, with a radio mast on the fuselage. The system worked on 66–77 MHz, a higher frequency than Knickebein. Ground transmitters sent pulses at a rate of 180 per minute. X-Gerät received and analysed the pulses, giving the pilot visual and aural directions. Three cross-beams intersected the beam along which the He 111 was flying. The first cross-beam alerted the bomb aimer, who activated a bombing clock when the second cross-beam was reached. When the third cross-beam was reached the bomb aimer activated a third trigger, which stopped the first hand of the clock, with the second hand continuing. When the second hand re-aligned with the first, the bombs were released. The clock mechanism was co-ordinated with the distances of the intersecting beams from the target so the target was directly below when the bombs were released. Y-Gerät was an automatic beam-tracking system and the most complex of the three devices, which was operated through autopilot. The pilot flew along an approach beam, monitored by a ground controller. Signals from the station were retransmitted by the bomber's equipment, which allowed the distance the bomber had travelled along the beam to be measured precisely. Direction-finding checks also enabled the controller to keep the pilot on course. The crew would be ordered to drop their bombs either by a code word from the ground controller or at the conclusion of the signal transmissions which would stop. The maximum range of Y-Gerät was similar to the other systems and it was accurate enough on occasion for specific buildings to be hit.
=== British countermeasures === In June 1940 a German prisoner of war was overheard boasting that the British would never find the Knickebein, even though it was under their noses. The details of the conversation were passed to an RAF Air Staff technical advisor, Dr R. V. Jones, who started a search which discovered that Luftwaffe Lorenz receivers were more than blind-landing devices. Jones began a search for German beams; Avro Ansons of the Beam Approach Training Development Unit (BATDU) were flown up and down Britain fitted with a 30 MHz receiver. Soon a beam was traced to Derby (which had been mentioned in Luftwaffe transmissions). The first jamming operations were carried out using requisitioned hospital electrocautery machines. The counter-operations were carried out by British Electronic Counter Measures (ECM) units under Wing Commander Edward Addison, No. 80 Wing RAF. The production of false radio navigation signals by re-transmitting the originals became known as meaconing using masking beacons (meacons). Up to nine special transmitters directed their signals at the beams in a manner that subtly widened their paths, making it harder for bomber crews to locate targets; confidence in the device was diminished by the time the Luftwaffe was ready to conduct big raids. German beacons operated on the medium-frequency band and the signals involved a two-letter Morse identifier followed by a lengthy time-lapse which enabled the Luftwaffe crews to determine the signal's bearing. The meacon system involved separate locations for a receiver with a directional aerial and a transmitter. The receipt of the German signal by the receiver was duly passed to the transmitter, the signal to be repeated. The action did not guarantee automatic success. If the German bomber flew closer to its own beam than the meacon then the former signal would come through the stronger on the direction finder. The reverse would apply only if the meacon were closer. In general, German bombers were likely to get through to their targets without too much difficulty. It was to be some months before an effective night-fighter force would be ready, and anti-aircraft defences only became adequate after the Blitz was over, so ruses were created to lure German bombers away from their targets. Throughout 1940 dummy airfields were prepared, good enough to stand up to skilled observation. An unknown number of bombs fell on diversionary ("Starfish sites") which simulated targets, or set up diversionary fires after initial incendiary attacks lit fires, drawing bombers to target areas. For industrial areas, fires and lighting were simulated. It was decided to recreate normal residential street lighting, and in non-essential areas, lighting to recreate heavy industrial targets. In those sites, carbon arc lamps were used to simulate flashes at tram overhead wires. Red lamps were used to simulate blast furnaces and locomotive fireboxes. Reflections made by factory skylights were created by placing lights under angled wooden panels. The use of diversionary techniques such as fires had to be made carefully. The fake fires could only begin when the bombing started over an adjacent target and its effects were brought under control. Too early and the chances of success receded; too late and the real conflagration at the target would exceed the diversionary fires. Another innovation was the boiler fire. These units were fed from two adjacent tanks containing oil and water. The oil-fed fires were then injected with water from time to time; the flashes produced were similar to those of the German C-250 and C-500 Flammbomben. The hope was that, if it could deceive German bombardiers, it would draw more bombers away from the real target.
First phase
Loge and Seeschlange
The first deliberate air raids on London were mainly aimed at the Port of London, causing severe damage. Late in the afternoon of 7 September 1940, the Germans began Operation London (Unternehmen Loge, where Loge was the codename for London) and Operation Sea Snake (Unternehmen Seeschlange), the air offensives against London and other industrial cities. Loge continued for 57 nights. A total of 348 bombers and 617 fighters took part in the attack. Initially the change in strategy caught the RAF off guard and caused extensive damage and civilian casualties. Some 107,400 gross tons (109,100 t) of shipping was damaged in the Thames Estuary and 1,600 civilians were casualties. Of this total around 400 were killed. The fighting in the air was more intense in daylight. Loge had cost the Luftwaffe 41 aircraft: 14 bombers, 16 Messerschmitt Bf 109s, seven Messerschmitt Bf 110s, and four reconnaissance aircraft. Fighter Command lost 23 fighters, with six pilots killed and another seven wounded. Another 247 bombers from Luftflotte 3 (Air Fleet 3) attacked that night. On 8 September the Luftwaffe returned; 412 people were killed and 747 severely wounded. On 9 September the OKL appeared to be backing two strategies. Its round-the-clock bombing of London was an immediate attempt to force the British government to capitulate, but it was also striking at Britain's vital sea communications to achieve a victory through siege. Although the weather was poor, heavy raids took place that afternoon on the London suburbs and the airfield at Farnborough. The day's fighting cost Kesselring and Luftflotte 2 (Air Fleet 2) 24 aircraft, including 13 Bf 109s. Fighter Command lost 17 fighters and six pilots. Over the next few days weather was poor and the next main effort would not be made until 15 September 1940.
On 15 September the Luftwaffe made two large daylight attacks on London along the Thames Estuary, targeting the docks and rail communications in the city. Its hope was to destroy its targets and draw the RAF into defending them, allowing the Luftwaffe to destroy their fighters in large numbers, thereby achieving air superiority. Large air battles broke out, lasting for most of the day. The first attack merely damaged the rail network for three days, and the second attack failed altogether. The air battle was later commemorated by Battle of Britain Day. The Luftwaffe lost 18 percent of the bombers sent on the operations that day and failed to gain air superiority. While Göring was optimistic the Luftwaffe could prevail, Hitler was not. On 17 September he postponed Operation Sea Lion (as it turned out, indefinitely) rather than gamble Germany's newly gained military prestige on a risky cross-Channel operation, particularly in the face of a sceptical Joseph Stalin in the Soviet Union. In the last days of the battle, the bombers became lures in an attempt to draw the RAF into combat with German fighters. But their operations were to no avail; the worsening weather and unsustainable attrition in daylight gave the OKL an excuse to switch to night attacks on 7 October. On 14 October the heaviest night attack to date saw 380 German bombers from Luftflotte 3 hit London. Around 200 people were killed and another 2,000 injured. British anti-aircraft defences (led by General Frederick Alfred Pile) fired 8,326 rounds and shot down only 2 bombers. On 15 October the bombers returned and about 900 fires were started by the mix of 376 tons (382 t) of high explosive and 10 tons of incendiaries dropped. Five main rail lines were cut in London and rolling stock damaged. Loge continued during October. 8200 tons (8,330 t) of bombs were dropped that month, about 10 percent in daylight, over 5400 tons (5,490 t) on London during the night. Birmingham and Coventry were subject to 450 long tons (457 t) of bombs between them in the last 10 days of October. Liverpool suffered 180 long tons (183 t) of bombs dropped. Hull and Glasgow were attacked but 715 long tons (726 t) of bombs were spread out all over Britain. The Metropolitan-Vickers works in Manchester was hit by 12 long tons (12.2 t) of bombs. Little tonnage was dropped on Fighter Command airfields; Bomber Command airfields were hit instead. Luftwaffe policy at this point was primarily to continue progressive attacks on London, chiefly by night attack; second, to interfere with production in the vast industrial arms factories of the West Midlands, again chiefly by night attack; and third to disrupt plants and factories during the day by means of fighter-bombers.
Kesselring, commanding Luftflotte 2, was ordered to send 50 sorties per night against London and attack eastern harbours in daylight. Sperrle, commanding Luftflotte 3, was ordered to dispatch 250 sorties per night including 100 against the West Midlands. Seeschlange would be carried out by Fliegerkorps X (10th Air Corps) which concentrated on mining operations against shipping. It also took part in the bombing over Britain. By 19/20 April 1941 it had dropped 3,984 mines, 1⁄3 of the total dropped. The mines' ability to destroy entire streets earned them respect in Britain, but several fell unexploded into British hands allowing counter-measures to be developed which damaged the German anti-shipping campaign. By mid-November 1940, when the Germans adopted a changed plan, more than 11,600 long tons (11,800 t) of high explosive and nearly 1,000,000 incendiaries had fallen on London. Outside the capital, there had been widespread harassing activity by single aircraft, as well as fairly strong diversionary attacks on Birmingham, Coventry and Liverpool, but no major raids. The London docks and railways communications had taken a heavy pounding, and much damage had been done to the railway system outside. In September, there had been no less than 667 hits on railways in Great Britain, and at one period, between 5,000 and 6,000 wagons were standing idle from the effect of delayed action bombs. But the great bulk of the traffic went on, and Londoners—though they glanced apprehensively each morning at the list of closed stretches of line displayed at their local station, or made strange detours round back streets in the buses—still got to work. For all the destruction of life and property, the observers sent out by the Ministry of Home Security failed to discover the slightest sign of a break in morale. More than 13,000 civilians had been killed, and almost 20,000 injured, in September and October alone, but the death toll was much less than expected. In late 1940, Churchill credited the shelters. Wartime observers perceived the bombing as indiscriminate. An American observer named Ralph Ingersoll reported the bombing was inaccurate and did not hit targets of military value, but destroyed the surrounding areas. He wrote that Battersea Power Station, one of the largest landmarks in London, received only a minor hit. In fact, on 8 September 1940 both Battersea and West Ham Power Station were both shut down after the 7 September daylight attack on London. In the case of Battersea power station, an unused extension was hit and destroyed during November but the station was not put out of action during the night attacks. It is not clear whether the power station or any specific structure was targeted during the German offensive as the Luftwaffe could not accurately bomb select targets during night operations. In the initial operations against London, it did appear as if rail targets and the bridges over the Thames had been singled out: Victoria Station was hit by four bombs and suffered extensive damage. The bombing disrupted rail traffic through London without destroying any of the crossings. On 7 November, St Pancras, Kensal and Bricklayers Arms stations were hit and several lines of Southern Rail were cut on 10 November. The British government grew anxious about the delays and disruption of supplies during the month. Reports suggested the attacks blocked the movement of coal to the Greater London regions and urgent repairs were required. Attacks against East End docks were effective and many Thames barges were destroyed. The London Underground rail system was also affected; high explosive bombs damaged the tunnels rendering some unsafe. The London Docklands, in particular, the Royal Victoria Dock, received many hits and Port of London trade was disrupted. In some cases the concentration of the bombing and resulting conflagration created firestorms of 1,000 °C (2000 °F). The Ministry of Home Security reported that although the damage caused was "serious" it was not "crippling" and the quays, basins, railways and equipment remained operational.
Improvements in British defences
British night air defences were in a poor state. Few anti-aircraft guns had fire-control systems, and the underpowered searchlights were usually ineffective against aircraft at altitudes above 12,000 ft (3,700 m). In July 1940, only 1,200 heavy and 549 light guns were deployed in the whole of Britain. Of the "heavies", some 200 were of the obsolescent 3 in (76 mm) type; the remainder were the effective 4.5 in (110 mm) and 3.7 in (94 mm) guns, with a theoretical ceiling of over 30,000 ft (9,100 m) but a practical limit of 25,000 ft (7,600 m) because the predictor in use could not accept greater heights. The light guns, about half of which were of the excellent Bofors 40 mm, dealt with aircraft only up to 6,000 ft (1,800 m). Although the use of the guns improved civilian morale, with the knowledge the German bomber crews were facing the barrage, it is now believed that the anti-aircraft guns achieved little and in fact the falling shell fragments caused more British casualties on the ground. Few fighter aircraft were able to operate at night. Ground-based radar was limited, and airborne radar and RAF night fighters were generally ineffective. RAF day fighters were converting to night operations and the interim Bristol Blenheim night fighter conversion of the light bomber was being replaced by the powerful Beaufighter, but this was only available in very small numbers. By the second month of the Blitz the defences were not performing well. London's defences were rapidly reorganised by General Pile, the Commander-in-Chief of Anti-Aircraft Command. The difference this made to the effectiveness of air defences is questionable. The British were still one-third below the establishment of heavy anti-aircraft artillery AAA (or ack-ack) in May 1941, with only 2,631 weapons available. Dowding had to rely on night fighters. From 1940 to 1941, the most successful night-fighter was the Boulton Paul Defiant; its four squadrons shot down more enemy aircraft than any other type. AA defences improved by better use of radar and searchlights. Over several months, the 20,000 shells spent per raider shot down in September 1940, was reduced to 4,087 in January 1941 and to 2,963 shells in February 1941. Aircraft interception radar (AI) then available was unreliable. The heavy fighting in the Battle of Britain had eaten up most of Fighter Command's resources, so there was little investment in night fighting. Bombers were flown with airborne search lights out of desperation but to little avail. Of greater potential was the GL (gun-laying) radar and searchlights with fighter direction from RAF fighter control rooms to begin a GCI system (Ground Control-led Interception) under Group-level control (No. 10 Group RAF, No. 11 Group RAF and No. 12 Group RAF). Whitehall's disquiet at the failures of the RAF led to the replacement of Dowding (who was already due for retirement) with Sholto Douglas on 25 November. Douglas set about introducing more squadrons and dispersing the few GL sets to create a carpet effect in the southern counties. Still, in February 1941, there remained only seven squadrons with 87 pilots, under half the required strength. The GL carpet was supported by six GCI sets controlling radar-equipped night-fighters. By the height of the Blitz, they were becoming more successful. The number of contacts and combats rose in 1941, from 44 and two in 48 sorties in January 1941, to 204 and 74 in May (643 sorties). But even in May, 67 percent of the sorties were visual cat's-eye missions. Curiously, while 43 percent of the contacts in May 1941 were by visual sightings, they accounted for 61 percent of the combats. Yet when compared with Luftwaffe daylight operations, there was a sharp decline in German losses to one percent. If a vigilant bomber crew could spot the fighter first, they had a decent chance of evading it. Nevertheless, it was radar that proved to be the critical weapon in the night battles over Britain from this point onward. Dowding had introduced the concept of aircraft interception radar and encouraged its usage. Eventually, it would become a success. On the night of 22/23 July 1940, Flying Officer Cyril Ashfield (pilot), Pilot Officer Geoffrey Morris (air observer) and Flight Sergeant Reginald Leyland (aircraft intercept radar operator) of the Fighter Interception Unit became the first pilot and crew to intercept and destroy an enemy aircraft using onboard radar to guide them to a visual interception, when their AI night fighter brought down a Do 17 off Sussex. On 19 November 1940 the RAF night fighter ace John Cunningham shot down a Ju 88 bomber using aircraft interception radar, just as Dowding had predicted. By mid-November, nine squadrons were available, but only one was equipped with Beaufighters (No. 219 Squadron RAF at RAF Kenley). By 16 February 1941, this had grown to 12; with 5 equipped, or partially equipped with Beaufighters spread over 5 Groups.
Italian Air Corps
The Corpo Aereo Italiano (literally, "Italian Air Corps"), or CAI, was an expeditionary force from the Italian Regia Aeronautica (Italian Royal Air Force) that participated in the Battle of Britain and the Blitz during the final months of 1940. The Air Corps was created by Italian dictator Benito Mussolini to assist his German ally during the Battle of Britain. On 10 September 1940, the CAI was formed, under the command of Generale di Squadra Aerea Rino Corso Fougier. The corps comprised 50 Fiat CR.42 biplane fighter, 45 Fiat G.50 Freccia monoplane fighters and a squadron of Fiat BR.20 twin engined bombers. The first raid was a night time bombing mission when 18 BR.20s attacked Harwich and Felixstowe on 24/25 October. On 29 October 15 bombers with a heavy fighter escort attacked Ramsgate during the daytime. There were 8 further night time bomber attacks on Harwich and Ipswich and one daylight bomber raid of Harwich with an escort of 40 fighters. The last raid was by 5 bombers against Ipswich on the night of 2 January. In total 54.3 tons (55.2 tonnes) of bombs were dropped in 102 sorties.
Second phase
=== Night attacks === From November 1940 to February 1941 the Luftwaffe shifted its strategy and attacked other industrial cities. In particular, the West Midlands were targeted. On the night of 13/14 November, 77 He 111s of Kampfgeschwader 26 (26th Combat Wing, or KG 26) bombed London, while 63 from KG 55 hit Birmingham. The next night, a large force hit Coventry. "Pathfinders" from 12 Kampfgruppe 100 (Combat Group 100 or KGr 100) led 437 bombers from KG 1, KG 3, KG 26, KG 27, KG 55 and Lehrgeschwader 1 (1st Training Wing, or LG 1) which dropped 350 long tons (356 t) of high explosive, 50 long tons (50.8 t) of incendiaries, and 127 parachute mines. Other sources say 449 bombers and a total of 470 long tons (478 t) of bombs were dropped. The raid against Coventry was particularly devastating, and led to widespread use of the phrase "to coventrate". Over 10,000 incendiaries were dropped. Around 21 factories were seriously damaged in Coventry, and loss of public utilities stopped work at nine others, disrupting industrial output for several months. The historic cathedral was all but destroyed together with most of the city centre in the massive firestorm. Only one bomber was lost, to anti-aircraft fire, despite the RAF flying 125 night sorties. No follow-up raids were made, as OKL underestimated the British power of recovery (as Bomber Command would do over Germany from 1943 to 1945). The Germans were surprised by the success of the attack. The strategic effect of the raid was a brief 20 percent dip in aircraft production. Five nights later, Birmingham was hit by 369 bombers from KG 54, KG 26, and KG 55. By the end of November, 1,100 bombers were available for night raids. An average of 200 were able to strike per night. This weight of attack went on for two months, with the Luftwaffe dropping 12,400 long tons (12,600 t) of bombs. In November 1940, 6,000 sorties and 23 major attacks (more than 100 tons [102 t] of bombs dropped) were flown. Two heavy attacks (50 long tons (51 t) of bombs) were also flown. In December, only 11 major and five heavy attacks were made. Probably the most devastating attack occurred on the evening of 29 December, when German aircraft attacked the City of London itself with incendiary and high explosive bombs, causing a firestorm that has been called the Second Great Fire of London. The first group to use these incendiaries was Kampfgruppe 100 which despatched 10 "pathfinder" He 111s. At 18:17, it released the first of 10,000 firebombs, eventually amounting to 300 dropped per minute. Altogether, 130 German bombers destroyed the historical centre of London. Civilian casualties on London throughout the Blitz amounted to 28,556 killed, and 25,578 wounded. The Luftwaffe had dropped 16,331 long tons (16,593 t) of bombs. Not all of the Luftwaffe effort was made against inland cities. Port cities were also attacked to try to disrupt trade and sea communications. In January 1941 Swansea was bombed four times, on 17 January very heavily, when around 100 bombers dropped a high concentration of incendiaries, some 32,000 in all. The main damage was inflicted on the commercial and domestic areas. Heavy and sustained bombing occurred in February in the 'Three Nights' Blitz' from 19 to 21 February. A total of 230 people were killed and 397 were injured. Swansea was selected by the Germans as a legitimate strategic target due to its importance as a port and docks and the oil refinery just beyond, and its destruction was key to Nazi German war efforts as part of their strategic bombing campaign aimed at crippling coal export and demoralizing civilians and emergency services. Waves of 150 bombers destroyed vast swaths of Southsea (Portsmouth) and Gosport with 40,000 incendiaries. Warehouses, rail lines and houses were destroyed and damaged, but the docks were largely untouched. In January and February 1941, Luftwaffe serviceability rates declined until just 551 of 1,214 bombers were combat-worthy. Seven major and eight heavy attacks were flown, but the weather made it difficult to keep up the pressure. Still, at Southampton, attacks were so effective morale did give way briefly with civilian authorities leading people en masse out of the city.
Strategic or "terror" bombing
Although official German air doctrine did target civilian morale, it did not espouse the attacking of civilians directly. It hoped to destroy morale by destroying the enemy's factories and public utilities as well as its food stocks (by attacking shipping). Nevertheless, its official opposition to attacks on civilians became an increasingly moot point when large-scale raids were conducted in November and December 1940. Although not encouraged by official policy, the use of mines and incendiaries, for tactical expediency, came close to indiscriminate bombing. Locating targets in skies obscured by industrial haze meant the target area needed to be illuminated and hit "without regard for the civilian population". Special units, such as KGr 100, became the Beleuchtergruppe (Firelighter Group), which used incendiaries and high explosives to mark the target area. The tactic was expanded into Feuerleitung (Blaze Control) with the creation of Brandbombenfelder (Incendiary Fields) to mark targets. These were marked out by parachute flares. Then bombers carrying SC 1000 (1,000 kg (2,205 lb)), SC 1400 (1,400 kg (3,086 lb)), and SC 1800 (1,800 kg (3,968 lb)) "Satan" bombs were used to level streets and residential areas. By December, the SC 2500 (2,500 kg (5,512 lb)) "Max" bomb was used. These decisions, apparently taken at the Luftflotte or Fliegerkorps level, meant attacks on individual targets were gradually replaced by what was, for all intents and purposes, an unrestricted area attack or Terrorangriff (terror attack). Part of the reason for this was inaccuracy of navigation. The effectiveness of British countermeasures against Knickebein caused the Luftwaffe to prefer fire light instead for target marking and navigation. The shift from precision bombing to area attack is indicated in the tactical methods and weapons dropped. KGr 100 increased its use of incendiaries from 13 to 28 per cent. By December this had increased to 92 per cent. Use of incendiaries, which were inherently inaccurate, indicated much less care was taken to avoid civilian property close to industrial sites. Other units ceased using parachute flares and opted for explosive target markers. Captured German aircrews also indicated the homes of industrial workers were deliberately targeted.
