Battle of Britain - 10 July – 31 October 1940

The Battle of Britain is the name given to the air campaign waged by the German Air Force (Luftwaffe) against the United Kingdom during the summer and autumn of 1940. The objective of the campaign was to gain air superiority over the Royal Air Force (RAF), especially Fighter Command. The name derives from a famous speech delivered by Prime Minister Winston Churchill in the House of Commons: "The Battle of France is over. I expect the Battle of Britain is about to begin..." The Battle of Britain was the first major campaign to be fought entirely by air forces, and was also the largest and most sustained aerial bombing campaign to that date. From July 1940 coastal shipping convoys and shipping centres, such as Portsmouth were the main targets; one month later the Luftwaffe shifted its attacks to RAF airfields and infrastructure. As the battle progressed the Luftwaffe also targeted aircraft factories and ground infrastructure. Eventually the Luftwaffe resorted to attacking areas of political significance and using terror bombing tactics. The failure of Germany to achieve its objectives of destroying Britain's air defences, or forcing Britain to negotiate an armistice or an outright surrender is considered its first major defeat and one of the crucial turning points in the war.If Germany had gained air superiority, Adolf Hitler might have launched Operation Sea Lion, an amphibious and airborne invasion of Britain. Following the evacuation of British and French soldiers from Dunkirk and the French surrender on 22 June 1940, Hitler was mainly focused on the possibilities of invading The Soviet Union while believing that the British, defeated on the continent and without European allies, would quickly come to terms.Although the Foreign Secretary, Lord Halifax, and an element of British public and political sentiment favoured a negotiated peace with an ascendant Germany, Winston Churchill, newly installed as Prime Minister, and a majority of his Cabinet refused to consider an armistice with Hitler.Instead Churchill used his skilful rhetoric to harden public opinion against capitulation, and to prepare the British for a long war. On 11 July, Großadmiral Erich Raeder, Commander-in-Chief of the Kriegsmarine (German Navy), told Hitler that an invasion could only be contemplated as a last resort, and only then with full air superiority. The Kriegsmarine had been nearly crippled by the Norwegian Campaign, with many of its ships having been sunk or damaged, while the Royal Navy still had over 50 destroyers, 21 cruisers and eight battleships in the British Home Fleet.There was little the weakened Kriegsmarine could do to stop the Royal Navy from intervening. The only alternative was to use the Luftwaffe's dive bombers and torpedo bombers, which required air superiority to operate effectively. On 16 July, although he agreed with Raeder, Hitler ordered the preparation of a plan to invade Britain;he also hoped that news of the preparations would frighten Britain into negotiating peace. "Directive No. 16; On the Preparation of a Landing Operation against England" read, in part, as follows: Since England, despite its militarily hopeless situation, still has not shown any signs of being prepared to negotiate, I have decided to prepare a landing operation against England and, if necessary, carry it out. The objective of this operation is to eliminate the English home country as a base for the continuation of the war against Germany... 2) Included in these preparations is the bringing about of those preconditions which make a landing in England possible; a) The English air force must have been beaten down to such an extent morally and in fact that it can no longer muster any power of attack worth mentioning against the German crossing. All preparations were to be made by mid-August. The plan, code named Unternehmen Seelöwe ("Operation Sealion"), was submitted by the OKW (Oberkommando der Wehrmacht or "High Command of the Armed Forces") and was scheduled to take place in mid-September 1940. Seelöwe called for landings on the south coast of Great Britain, backed by an airborne assault. Neither Hitler nor OKW believed it would be possible to carry out a successful amphibious assault on Britain until the RAF had been neutralised. Raeder believed that air superiority might make a successful landing possible although it would be a risky operation and required "absolute mastery over the Channel by our air forces". Conversely Großadmiral Karl Dönitz believed air superiority was "not enough". Dönitz stated, "we possessed neither control of the air or the sea; nor were we in any position to gain it".Some historians, such as Derek Robinson, have agreed with Dönitz. Robinson argues that the massive superiority of the Royal Navy over the Kriegsmarine would have made Sealion a disaster and the Luftwaffe could not have prevented decisive intervention by British cruisers and destroyers, even with air superiority. Fighters The Luftwaffe's Messerschmitt Bf 109E and Bf 110C squared off against the RAF's workhorse Hurricane Mk I and the less numerous Spitfire Mk I. The Bf 109E had a better climb rate and was 10 to 30 mph faster than the Hurricane, depending on altitude.In September 1940 the more powerful Mk IIa series 1 Hurricanes started entering service although only in small numbers.This version was capable of a maximum speed of 342 mph, some 25 to 30 mph faster than the Mk I.The performance of the Spitfire over Dunkirk came as a surprise to the Jagdwaffe, although the German pilots retained a strong belief that the 109 was the superior fighter. However, the Bf 109E had a much larger turning circle than either the Hurricane or the Spitfire.The two British fighters were equipped with eight Browning 303 machine guns, while most Bf 109Es had two machine guns and two wing cannons. The Bf 109E and the Spitfire were superior to each other in key areas; for instance, at some altitudes, the 109 could out-climb the British fighter. In general, though, as Alfred Price noted in The Spitfire Story: ...the differences between the Spitfire and the Me 109 in performance and handling were only marginal, and in a combat they were almost always surmounted by tactical considerations: which side had seen the other first, had the advantage of sun, altitude, numbers, pilot ability, tactical situation, tactical co-ordination, amount of fuel remaining, etc. The Bf 109 was also used as a fighter-bomber—the E-4/B and E-7 models could carry a 250 kg bomb underneath the fuselage. The Bf 109, unlike the Stuka, could fight on equal terms with RAF fighters after releasing its ordnance. At the start of the battle, the twin-engine Messerschmitt Bf 110 long range Zerstörer ("Destroyer") was also expected to engage in air-to-air combat while escorting the Luftwaffe bomber fleet. Although the 110 was faster than the Hurricane and almost as fast as the Spitfire, its lack of manoeuvrability and acceleration meant that it was a failure as a long-range escort fighter. On 13 and 15 August, 13 and 30 aircraft were lost, the equivalent of an entire Gruppe, and the type's worst losses during the campaign.This trend continued with a further eight and 15 lost on 16 and 17 August.Göring ordered the Bf 110 units to operate "where the range of the single-engined machines were not sufficient". The most successful role of the 110 during the battle was as a Schnellbomber (fast bomber). The 110 usually used a shallow dive to bomb the target and escaped at high speed.One unit, Erprobungsgruppe 210, proved that the Bf 110 could be used to good effect in attacking small or "pinpoint" targets. The RAF's Boulton Paul Defiant had some initial success over Dunkirk because of its resemblance to the Hurricane; Luftwaffe fighters attacking from the rear were surprised by its unusual gun turret. However, during the Battle of Britain, this single-engine two-seater proved to be hopelessly outclassed. For various reasons, the Defiant lacked any form of forward firing armament and the heavy turret meant that it could not out-run or out-manoeuvre either the Bf 109 or the Bf 110. By the end of August, after disastrous losses, the aircraft was withdrawn from daylight service. There has been some criticism of the decision to keep these aircraft (along with the Fairey Battle in RAF Bomber Command) operational instead of retiring and scrapping them, allowing their Merlin engines to be turned over to fighters and their pilots (about three thousand in all) to be retrained on Hurricanes, thereby freeing large numbers of high-time, combat-experienced Hurricane pilots for Spitfires. Fighter formations In the late 1930s, Fighter Command expected to face only bombers over Britain, not single-engine fighters. With this in mind, a series of "Fighting Area Tactics" were formulated and rigidly adhered to, involving a series of manoeuvres designed to concentrate a squadron's firepower to bring down bombers: with no apparent prospect of escorting fighters to worry about, RAF fighter pilots flew in tight, vee-shaped sections ("vics") of three. These restricted squadrons to tight 12 aircraft formations composed of four sections in another tight "V". With this formation, only the squadron leader at the front was free to watch for the enemy; the other pilots had to concentrate on keeping station.RAF fighter training also emphasised by-the-book attacks by sections breaking away in sequence. Fighter Command recognised the weaknesses of this rigid structure early in the battle, but it was felt too risky to change tactics during the battle, because replacement pilots – often with only minimal flying time – could not be readily retrained,and inexperienced RAF pilots needed firm leadership in the air only rigid formations could provide.German pilots dubbed the RAF formations Idiotenreihen ("rows of idiots") because they left squadrons vulnerable to attack. By contrast the Luftwaffe employed a loose section of two (nicknamed the Rotte), based on a leader (Rottenführer) followed at a distance of about 183 meters (200 yards)by his wingman (nicknamed the Rottenhund or Katschmareks), who also flew slightly higher and was trained to always stay with his leader. While the leader was free to search for enemy aircraft, and could cover his wingman's blind spots, his wingman could concentrate on searching the airspace in the leader's blind spots, behind and below. Attacking aircraft could be sandwiched between the two 109s.[This formation was developed based on principles formulated by First World War ace Oswald Boelcke in 1916. The Finnish Air Force, from 1934 on, adopted similar formations, called partio (patrol; two aircraft) and parvi (two patrols; four aircraft),for comparable reasons, though Luftwaffe pilots (led by Günther Lützow and Werner Mölders among others, during the Spanish Civil War) are generally given credit. In the Luftwaffe formations, the pair allowed the Rottenführer to concentrate on getting kills. This latter aspect, however, caused some grievances in the lower ranks because it was felt that the high scores of some Rottenführer came at the expense of the Katschmareks. During the Battle of Britain, a pilot who shot down 20 aircraft was automatically awarded the Ritterkreuz (Knight's Cross), to which was added the Oak Leaves, Swords and Diamonds for each additional 20 aircraft. Those pilots who appeared to have a constant desire for these awards were said to be suffering from Halsweh (a sore throat). Few wingmen in Luftwaffe fighter formations were able to shoot down opposing aircraft, while their formation leaders were scoring heavily. Two of these sections were usually teamed up into a Schwarm, where all the pilots could watch what was happening around them. Each Schwarm in a Staffel flew at staggered heights and with 183 meters (200 yards) of room between them, making the formation difficult to spot at longer ranges and allowing for a great deal of flexibility.By utilising a tight "cross-over" turn, a Schwarm could quickly change direction. The 110 fighters adopted the same Schwarm formation as the 109s, but were seldom able to use this to the same advantage. When attacked, Zerstörergruppen increasingly resorted to forming large "defensive circles". Each 110 guarded the tail of the aircraft ahead of it. Göring ordered that they be renamed "offensive circles" in a vain bid to improve rapidly declining morale.These conspicuous formations were often successful in attracting RAF fighters that were sometimes "bounced" by high-flying 109s. This led to the often repeated myth that the 110s were escorted by 109s. The 110's most successful method of attack was the "bounce" from above. Front line RAF pilots were acutely aware of the inherent deficiencies of their own tactics. A compromise was adopted whereby squadron formations used much looser formations with one or two "weavers" flying independently above and behind to provide increased observation and rear protection; these tended to be the least experienced men and were often the first to be shot down without the other pilots even noticing that they were under attack.During the battle, 74 Squadron under Squadron Leader Adolph "Sailor" Malan adopted a variation of the German formation called the "fours in line astern", which was a vast improvement on the old three aircraft "vic." Malan's formation was later generally used by Fighter Command. Bombers The Luftwaffe's four primary bombers were the Heinkel He 111, Dornier Do 17, and Junkers Ju 88 for level bombing, and the Junkers Ju 87 Stuka for diving attacks. The Heinkel He 111 was used in greater numbers than the others during the conflict and is better known, partly due to its distinctive wing shape. Each level bomber also had a few reconnaissance versions that were used during the battle. Although successful in previous Luftwaffe engagements, the Stuka suffered heavy losses in the Battle of Britain, particularly on 18 August, due to its slow speed and vulnerability to fighter interception after the dive bombing. As a result of the losses and limited payload and range, Stuka units were largely removed from operations over England and concentrated on shipping instead until they were re-deployed to the Eastern Front in 1941. They returned on occasion, such as on the 13 September attack on Tangmere airfield. The remaining three bomber types differed in their capabilities; the Heinkel 111 was the slowest, the Ju 88, once its mainly externally carried bomb load was dropped, was the fastest, and the Do 17 had the smallest bomb load.All three bomber types suffered heavy losses from British fighters, but the Ju 88 disproportionately so. Later in the conflict, when night bombing became more frequent, all three were used. However, due to its reduced bomb load, the lighter Do 17 was used less than the He 111 and Ju 88 for this purpose. On the British side, three bombers were mostly used on night operations against targets such as factories, invasion ports and railway centres; the Armstrong Whitworth Whitley, the Handley-Page Hampden and the Vickers Wellington were classified as heavy bombers by the RAF, although the Hampden was a medium bomber comparable to the He 111. The twin-engined Bristol Blenheim and the obsolescent single-engined Fairey Battle were both light bombers; the Blenheim was the most numerous of the aircraft equipping RAF Bomber Command and was used in attacks against shipping, ports, airfields and factories on the continent by day and by night, while the Battle was rarely used on operations. Pilots Before the war, the RAF's processes for selecting potential candidates were more concerned with social standing than actual aptitude.By summer 1940, there were about 9,000 pilots in the RAF for approximately 5,000 aircraft, most of which were bombers.However, the problem of pilot shortage was self-inflicted, due to inefficiencies in training and assignment. With aircraft production running at 300 each week, only 200 pilots were trained in the same period. In addition, more pilots were allocated to squadrons than there were aircraft. Another problem was that only about 30% of the 9,000 pilots were assigned to operational squadrons; 20% of the pilots were involved in conducting pilot training, and a further 20% were undergoing further instruction, like those offered in Canada to the Commonwealth trainees, although already qualified. The rest were assigned to staff positions, since RAF policy dictated that only pilots could make many staff and operational command decisions, even in engineering matters. At the height of fighting, and despite Churchill's insistence, only 30 pilots were released to the front line from administrative duties.For these reasons, the RAF had fewer experienced pilots at the start of the battle, and it was the lack of trained pilots in the fighting squadrons, rather than the lack of aircraft, that became the greatest concern for Air Chief Marshal Hugh Dowding, Commander of Fighter Command. Drawing from regular RAF forces and the Auxiliary Air Force and the Volunteer Reserve, the British could muster some 1,103 fighter pilots on 1 July. Replacement pilots, with little flight training and often no gunnery training, suffered high casualty rates. Due mostly to more efficient training, the Luftwaffe could muster a larger number (1,450) of more experienced fighter pilots.Drawing from a cadre of Spanish Civil War veterans, they had comprehensive courses in aerial gunnery and instructions in tactics suited for fighter-versus-fighter combat.Luftwaffe training manuals also discouraged heroism, stressing the utmost importance of attacking only when the odds were in the pilot's favour. Luftwaffe strategy The Luftwaffe was devised to provide tactical support for the army on the battlefield. During the blitzkrieg offensives against Poland, Denmark and Norway and France and the Low Countries, the Luftwaffe had co-operated fully with the Wehrmacht. For the Battle of Britain however, the Luftwaffe had to operate in a strategic role, something for which it was unsuited. Its main task was to ensure air supremacy over southeast England, to pave the way for an invasion fleet. The Luftwaffe regrouped after the Battle of France into three Luftflotten (Air Fleets) on Britain's southern and northern flanks. Luftflotte 2, commanded by Generalfeldmarschall Albert Kesselring, was responsible for the bombing of southeast England and the London area. Luftflotte 3, under Generalfeldmarschall Hugo Sperrle, targeted the West Country, Midlands, and northwest England. Luftflotte 5, led by Generaloberst Hans-Jürgen Stumpff from his headquarters in Norway, targeted the north of England and Scotland. As the battle progressed, command responsibility shifted, with Luftflotte 3 taking more responsibility for the nighttime Blitz attacks while the main daylight operations fell upon Luftflotte 2's shoulders. Initial Luftwaffe estimates were that it would take four days to defeat the RAF Fighter Command in southern England. This would be followed by a four-week offensive during which the bombers and long-range fighters would destroy all military installations throughout the country and wreck the British aircraft industry. The campaign was planned to begin with attacks on airfields near the coast, gradually moving inland to attack the ring of sector airfields defending London. Later reassessments gave the Luftwaffe five weeks, from 8 August to 15 September, to establish temporary air superiority over England.To achieve this goal, Fighter Command had to be destroyed, either on the ground or in the air, yet the Luftwaffe had to be able to preserve its own strength to be able to support the invasion; this meant that the Luftwaffe had to maintain a high "kill ratio" over the RAF fighters. The only alternative to the goal of air superiority was a terror bombing campaign aimed at the civilian population, but this was considered a last resort and it was expressly forbidden by Hitler. The Luftwaffe kept broadly to this scheme, but its commanders had differences of opinion on strategy. Sperrle wanted to eradicate the air defence infrastructure by bombing it. His counterpart, Kesselring, championed attacking London directly—either to bombard the British government into submission or to draw RAF fighters into a decisive battle. Göring did nothing to resolve this disagreement between his commanders, and only vague directives were set down during the initial stages of the battle, with Göring seemingly could not decide upon which strategy to pursue.He seemed at times obsessed with maintaining his own power base in the Luftwaffe and indulging his outdated beliefs on air fighting, which were later to lead to tactical and strategic errors. Tactics Messerschmitt Bf 109ELuftwaffe tactics were influenced by their fighters. The Bf 110 proved too vulnerable to the nimble single-engined RAF fighters. This meant the bulk of fighter escort duties fell on the Bf 109. Fighter tactics were then complicated by bomber crews who demanded closer protection. After the hard-fought battles of 15 and 18 August, Göring met with his unit leaders. During this conference, the need for the fighters to meet up on time with the bombers was stressed. It was also decided that one bomber Gruppe could only be properly protected by several Gruppen of 109s. In addition Göring stipulated that as many fighters as possible were to be left free for Freie Jagd (this fighter sweep would precede a raid to try to sweep defenders out of the raid's path). The Ju 87 units, which had suffered heavy casualties, were only to be used under favourable circumstances.In early September, due to increasing complaints from the bomber crews about RAF fighters seemingly able to get through the escort screen, Göring ordered an increase in close escort duties. This decision shackled many of the Bf 109s to the bombers and, although they were more successful at protecting the bomber forces, casualties amongst the fighters mounted primarily because they were forced to fly and manoeuvre at reduced speeds. The Luftwaffe consistently varied its tactics in its attempts to break through the RAF defences. It launched many free-roving fighter sweeps, known as Freie Jagd ("Free Hunts"), to draw up RAF fighters. RAF fighter controllers, however, were often able to detect these and position squadrons to avoid them, keeping to Dowding's plan to preserve fighter strength for the bomber formations. The Luftwaffe also tried using small formations of bombers as bait, covering them with large numbers of escorts. This was more successful, but escort duty tied the fighters to the bombers' slow speed and made them more vulnerable. By September, standard tactics for raids had become an amalgam of techniques. A Freie Jagd would precede the main attack formations. The bombers would fly in at altitudes between 16,000 feet (4,900 m) and 20,000 feet (6,100 m), closely escorted by fighters. Escorts were divided into two parts (usually Gruppen), some operating in close contact with the bombers, and others a few hundred yards away and a little above. If the formation was attacked from the starboard, the starboard section engaged the attackers, the top section moving to starboard and the port section to the top position. If the attack came from the port side the system was reversed. British fighters coming from the rear were engaged by the rear section and the two outside sections similarly moving to the rear. If the threat came from above, the top section went into action while the side sections gained height to be able to follow RAF fighters down as they broke away. If attacked, all sections flew in defensive circles. These tactics were skillfully evolved and carried out, and were extremely difficult to counter. Adolf Galland noted: We had the impression that, whatever we did, we were bound to be wrong. Fighter protection for bombers created many problems which had to be solved in action. Bomber pilots preferred close screening in which their formation was surrounded by pairs of fighters pursuing a zigzag course. Obviously, the visible presence of the protective fighters gave the bomber pilots a greater sense of security. However, this was a faulty conclusion, because a fighter can only carry out this purely defensive task by taking the initiative in the offensive. He must never wait until attacked because he then loses the chance of acting. We fighter pilots certainly preferred the free chase during the approach and over the target area. This gives the greatest relief and the best protection for the bomber force. The biggest disadvantage faced by Bf 109 pilots was that without the benefit of long-range drop tanks (which were introduced in limited numbers in the late stages of the battle), usually of 300 litre (79 US gallon) capacity, the 109s had an endurance of just over an hour and, for the 109E, a 600 km (360 mi) range. Once over Britain, a 109 pilot had to keep an eye on a red "low fuel" light on the instrument panel: once this was illuminated, he was forced to turn back and head for France. With the prospect of two long over-water flights, and knowing their range was substantially reduced when escorting bombers or during combat, the Jagdflieger coined the term Kanalkrankheit or "Channel sickness". Intelligence The Luftwaffe was ill-served by its lack of military intelligence about the British defences.The German intelligence services were fractured and plagued by rivalries; their performance was "amateurish".By 1940, there were few German agents operating in the UK and a handful of bungled attempts to insert spies into the country were foiled. As a result of intercepted radio transmissions, the Germans began to realise that the RAF fighters were being controlled from ground facilities; in July and August 1939, for example, the airship Graf Zeppelin, which was packed with equipment for listening in on RAF radio and RDF transmissions, flew around the coasts of Britain. Although the Luftwaffe correctly interpreted these new ground control procedures, they were incorrectly assessed as being rigid and ineffectual. A British radar system was well known to the Luftwaffe from intelligence gathered before the war, but the highly developed "Dowding system" linked with fighter control had been a well kept secret.Even when good information existed, such as a November 1939 Abwehr assessment of Fighter Command strengths and capabilities by Abteilung V, it was ignored if it did not match conventional preconceptions. On 16 July 1940, Abteilung V, commanded by Oberstleutnant "Beppo" Schmid, produced a report on the RAF and on Britain's defensive capabilities which was adopted by the frontline commanders as a basis for their operational plans. One of the most conspicuous failures of the report was the lack of information on the RAF's RDF network and control systems capabilities; it was assumed that the system was rigid and inflexible, with the RAF fighters being "tied" to their home bases.An optimistic and, as it turned out, erroneous conclusion reached was: D. Supply Situation... At present the British aircraft industry produces about 180 to 300 first line fighters and 140 first line bombers a month. In view of the present conditions relating to production (the appearance of raw material difficulties, the disruption or breakdown of production at factories owing to air attacks, the increased vulnerability to air attack owing to the fundamental reorganization of the aircraft industry now in progress), it is believed that for the time being output will decrease rather than increase.In the event of an intensification of air warfare it is expected that the present strength of the RAF will fall, and this decline will be aggravated by the continued decrease in production. Because of this statement, reinforced by another more detailed report, issued on 10 August, there was a mindset in the ranks of the Luftwaffe that the RAF would run out of frontline fighters.The Luftwaffe believed it was weakening Fighter Command at three times the actual attrition rate.Many times, the leadership believed Fighter Command's strength had collapsed, only to discover that the RAF were able to send up defensive formations at will. Throughout the battle, the Luftwaffe had to use numerous reconnaissance sorties to make up for the poor intelligence. Reconnaissance aircraft (at first mostly Dornier Do 17s, but increasingly Bf 110s) proved easy prey for British fighters, as it was seldom possible for them to be escorted by Bf 109s. Thus, the Luftwaffe operated "blind" for much of the battle, unsure of its enemy's true strengths, capabilities, and deployments. Many of the Fighter Command airfields were never attacked, while raids against supposed fighter airfields fell instead on bomber or coastal defence stations. The results of bombing and air fighting were consistently exaggerated, due to over-enthusiastic claims and the difficulty of confirmation over enemy territory. In the euphoric atmosphere of perceived victory, the Luftwaffe leadership became increasingly disconnected from reality. This lack of leadership and solid intelligence meant the Germans did not adopt consistent strategy, even when the RAF had its back to the wall. Moreover, there was never a systematic focus on one type of target (such as airbases, radar stations, or aircraft factories), so the already haphazard effort was further diluted. Air-sea rescue The Luftwaffe was much better prepared for the task of air-sea rescue than the RAF, with one unit, the Seenotdienst equipped with Heinkel He 59 floatplanes, specifically tasked with picking up downed aircrew from the North Sea, English Channel and the Dover Straits. In addition, Luftwaffe aircraft were equipped with life rafts and the aircrew were provided with sachets of a chemical called fluorescein which, on reacting with water, created a large, easy-to-see, bright green patch. In accordance with the Geneva Convention the He 59s were unarmed and painted white with civilian registration markings and red crosses. Nevertheless, RAF aircraft attacked these aircraft, as some were escorted by Bf 109s. After single He 59s were forced to land on the sea by RAF fighters, on 1 and 9 July respectively,a controversial order was issued to the RAF on 13 July; this stated that as of 20 July, Seenotdienst aircraft were to be shot down. One of the reasons given by Churchill was: We did not recognise this means of rescuing enemy pilots so they could come and bomb our civil population again... all German air ambulances were forced down or shot down by our fighters on definite orders approved by the War Cabinet. The Air Ministry issuing a communique to the German government on 14 July: It has come to the notice of His Majesty's Government in the United Kingdom that enemy aircraft in civilian markings and marked with the red cross have recently flown over British Ships at sea and near the British coast, and that they are being employed for purposes which His Majesty's Government cannot regard as being consistent with the privileges generally accorded to the Red Cross. His Majesty's Government desire to accord to ambulance aircraft reasonable facilities for the transportation of the sick and wounded, in accordance with Red Cross Convention, and aircraft engaged in the direct evacuation of sick and wounded will be respected, provided that they comply with the relevant provisions of the Geneva Convention. His Majesty's Government are unable, however, to grant immunity to such aircraft flying over areas in which operations are in progress on land or at sea, or approaching British or Allied territory, or territory in British occupation, or British or Allied ships. Ambulance aircraft which do not comply with the above will do so at their own risk and peril. The white He 59s were soon repainted in camouflage colours and armed with defensive machine guns. Although another four He 59s were shot down by RAF aircraft,the Seenotdienst continued to pick up downed Luftwaffe and Allied aircrew throughout the battle, earning praise from Adolf Galland for their gallantry. Royal Air Force strategy The keystone of the British defence was the complex infrastructure of detection, command, and control that ran the battle. This was the "Dowding System," after its chief architect, Air Chief Marshal Sir H.C.T. "Stuffy" Dowding, the leader of RAF Fighter Command. It has been pointed out by that much of the original air defence system, which Dowding inherited, had been set up from 1917 by Major General E B Ashmore. Dowding built upon and modernised many of the features which had been pioneered by Ashmore, including the use of two-way radio and the Royal Observer Corps (ROC).[However, the core of Dowding's system was implemented by Dowding himself: the use Radio Direction Finding (RDF, later called radar, for radio direction finding and ranging) was at his behest, and its use, supplemented by information by the ROC, was crucial to the RAF's ability to efficiently intercept incoming German aircraft.He also insisted on having the radar operators linked via telephone (whose wires were laid deep underground with concrete anti-bomb protection)to an operational centre: this was Fighter Command control at Bentley Priory.During the Battle several Coastal Command and Fleet Air Arm units came under Fighter Command control. Control systems Usually the first indications of incoming air raids were received by the Chain Home Radio Direction Finding (RDF) facilities which were located around the coastlines of the UK. In most circumstances, RDF could pick up formations of Luftwaffe aircraft as they organised over their own airfields. Once the raiding aircraft moved inland over England, the formations were also plotted by the Observer Corps. The information from RDF and the Observer Corps were sent through to the main operations room of Fighter Command Headquarters at Bentley Priory. The plots were assessed to determine whether they were "hostile" or "friendly". If hostile, the information was sent to the main "operations room", which was in a large underground bunker. Here the course information of each raid was plotted by WAAFs who received information by a telephone system. Additional intelligence was provided by the "Y" Service radio posts, which monitored enemy radio transmissions, and the "Ultra" decoding centre based at Bletchley Park. Colour coded counters representing each raid were placed on a large table, which had a map of the UK overlaid and squared off with a British Modified Grid. The colour of counter to use for a new sighting was determined by the time of the sighting, the proper colour being indicated by the minute hand of the sector clock. As the plots of the raiding aircraft moved, the counters were pushed across the map by magnetic "rakes". This system enabled the main "Fighter Controller" (usually of squadron leader rank) and Dowding to see quickly where each formation was heading and allowed an estimate to be made of possible targets. The age of the information was readily apparent from the colour of the counter. Because of the simplicity of the system, decisions could be made quickly and easily. Apart from the controller, most of the room and map information was operated by members of the WAAF. Before the war, there was still a great deal of doubt about the ability of women to stand up to battle conditions, with many airwomen employed on front-line RDF stations and aerodromes.Experience during the battle proved that such doubts were unfounded and the contribution of the WAAFs became essential to the RAF in its control and communications systems and in many other duties. This information was simultaneously sent to the headquarters of each Group (for example, RAF Uxbridge for 11 Group),where it was "filtered" through a filter room (that is, collated, cross-checked and simplified), before being sent through to another operations room, again housed in an underground bunker. Because Group had tactical control of the battle the operations room was different in layout from the one at Bentley Priory. The main map on the plotting table represented the Group command area and its associated airfields. Extensive radio and telephone equipment transmitted and received a constant flow of information from the various sector airfields as well as the Observer Corps, AA Command and the navy. The "Duty fighter controller" was (for example in 11 Group) Park's personal representative, whose job was to control how and when each raid would be dealt with. He ordered the squadrons airborne and positioned them as he thought best. Timing was of the essence, because "(e)ach minute of unnecessary delay waiting to make absolutely sure that the raid was coming in meant about 2,000 feet of vital altitude our fighters would not have when they met the enemy." (Wing Commander Lord Willoughby de Broke, Senior Fighter Controller, Uxbridge.) Each Group room had a "tote board" which showed each squadron available to that group. The tote board had a system of lights which enabled the controllers to see the squadron status: Released (not available); Available (airborne in 20 minutes); Readiness (airborne in 5 minutes); Standby (pilots in cockpit, airborne in 2 minutes); Airborne and moving into position; Enemy sighted; Ordered to land; Landed and refuelling/rearming. Next to the tote board, where it could be clearly seen, was a weather board which showed the state of the weather around each airfield. It was the responsibility of the WAAF plotters to continually update the tote and weather boards. A vital role was played by the telephone engineers of the GPO "who worked all hours repairing communications, installing completely new facilities in the emergency centres, and keeping the nervous system of Fighter Command functioning..." (Air Commodore Eric Roberts, Commander Middle Wallop Sector in 1940) Despite appearances, the Groups were not mutually supporting; Park, for instance, could only request - not demand - assistance from Brand (who usually co-operated), or from Leigh-Mallory (who often prevaricated). This was because Dowding had never issued standing orders to assist, nor had he created a method to co-ordinate it. There was a further problem in that the aircraft were not assigned equitably between Groups. While the most effective RAF fighter was the Spitfire, 70% of 11 Group aircraft were Hurricanes. "In total, less than a third of Britain's best fighters were operating in the key sector." Sectors The Group areas were subdivided into Sectors; each commanding officer was assigned between two and four squadrons. Sector Stations, comprising an aerodrome with a "Sector operations room", were the heart of this organisation, and they were also responsible for operating satellite aerodromes to which squadrons could be dispersed. The operations rooms duplicated those at the Group HQs, although they were on a smaller scale and most were still housed in brick, single-storey, tile-roofed structures above ground, where they were vulnerable to attack. By 1940, most were semi-protected by an earth bank or "blast wall" surrounding them which reached as high as the eaves. Fortunately for Fighter Command, Luftwaffe Intelligence was unaware of the importance of these rooms and most were left alone. The control rooms at Biggin Hill were destroyed by a raid on 31 August, but this was due to a chance bomb hit. Their vulnerability in time of war was appreciated and new airfields built during the expansion programme of the 1930s had new, bombproof Mk II, L-shaped structures. As a further precaution, emergency control rooms were set up in different locations away from the airfields, with small loss in efficiency; RAF Kenley, for example, could use an alternative room housed in a butcher's shop in nearby Caterham. The plotting table was laid out with a map of the sector and its airfields, and the tote and weather boards reflected this more localised information. When ordered by their Group HQ, the sector stations would "scramble" their squadrons into the air. Once airborne, the squadrons would be directed by radio-telephone (R/T) from their sector station. Squadrons could be ordered to patrol airfields or vital targets or be "vectored" to intercept incoming raids. As well as directing the fighter squadrons, Sector stations also controlled the anti-aircraft batteries in their area; an army officer sat beside each fighter controller and directed the gun crews when to open fire and, if RAF aircraft flew into the gun-zones, ordered the guns to cease fire. Limitations Though it was the most sophisticated air defence system in the world at that time, the Dowding System had many limitations, including, but not often stressed, its emphatic need for qualified ground maintenance personnel, many of whom had received their training under the Aircraft Apprentice scheme instituted by Hugh Trenchard. RDF (radar) was subject to significant errors and the Observer Corps had difficulties tracking raids at night and in bad weather. R/T (radio telephone) communications with airborne fighters were restricted because the standard radio set used by RAF fighters at the beginning of the battle was the TR9F HF set, which operated over two selectable frequencies in the band 4.3-6.6 Megahertz (MHz);the RAF soon realised that this equipment was limited in the range at which it could receive and transmit radio signals because of its limited power. In addition, the increase in the number of civil, military and foreign HF-band radio transmitters since the adoption of the TR9 meant that the signal often suffered from distortion and interference, making clear communication with the RAF fighters difficult. It was also restricted to a single frequency per squadron, making inter-squadron communication impossible.Finally, the system for tracking RAF fighters, known as HF/DF or "Huff-Duff", restricted sectors to a maximum of four squadrons in the air. The addition of IFF, "Pipsqueak", while a welcome help in identifying RAF aircraft, took up another radio channel. Starting in late September 1940 VHF T/R Type 1133 radios started replacing the TR9s. These had first been fitted to Spitfires of 54 and 66 Squadrons starting in October 1939, but production delays with the improved T/R 1143 set meant the bulk of Spitfires and Hurricanes were not fitted with this equipment until October 1940. The reception was much clearer over a longer range, and controllers and pilots had a wider range of communications channels to choose from. Effect of signals intelligence It is unclear how much the British intercepts of the Enigma cipher, used for high-security German radio communications, affected the battle. Ultra, the information obtained from Enigma intercepts, gave the highest echelons of the UK's command a view of German intentions. According to F. W. Winterbotham, who was the senior Air Staff representative in the Secret Intelligence Service,Ultra helped establish the strength and composition of the Luftwaffe's formations, the aims of the commanders and it provided early warning of some raids.In early August the decision was made that a small unit would be set up at Fighter Command headquarters (Stanmore) which would process the flow of information from Bletchley and provide Dowding only with the most essential Ultra material; thus the Air Ministry did not have to send a continual flow of information to Stanmore, preserving secrecy, and Dowding was not inundated with non-essential information. Keith Park and his controllers were also told about Ultra.In a further attempt to camouflage the existence of Ultra Dowding created a unit called 421 Flight. This unit (which later became 91 Squadron), was equipped with Hurricanes and Spitfires and sent out aircraft to search for and report Luftwaffe formations approaching England.In addition the radio listening service (known as Y Service), monitoring the patterns of Luftwaffe radio traffic, contributed considerably to the early warning of raids. Air-sea rescue One of the biggest oversights of the entire system was the lack of a proper air-sea rescue organisation. The RAF had started organising a system in 1940 with High Speed Launches (HSLs) based on flying boat bases and at a number of overseas locations, but it was still believed that the amount of cross-Channel traffic meant that there was no need for a rescue service to cover these areas. Downed pilots and aircrew, it was hoped, would be picked up by any boats or ships which happened to be passing by. Otherwise the local life boat would be alerted, assuming someone had seen the pilot going into the water. RAF aircrew were issued with a life jacket, nicknamed the "Mae West" but in 1940 it still required manual inflation, which was almost impossible for someone who was injured or in shock. The waters of the English Channel and Dover Straits are cold, even in the middle of summer, and clothing issued to RAF aircrew did little to insulate them against these freezing conditions. A conference in 1939 had placed air-sea rescue under Coastal Command. Because a number of pilots had been lost at sea during the "Channel Battle", on 22 August, control of RAF rescue launches was passed to the local naval authorities and 12 Lysanders were given to Fighter Command to help look for pilots at sea. In all some 200 pilots and aircrew were lost at sea during the battle. No proper air-sea rescue service was formed until 1941. Tactics The weight of the battle fell upon 11 Group. Keith Park's tactics were to dispatch individual squadrons to intercept raids. The intention was to subject attackers to continual attacks by relatively small numbers of aircraft and try to break up the tight formations of bombers. Once formations had fallen apart, stragglers could be picked off one by one. Where multiple squadrons reached a raid the procedure was for the slower Hurricanes to tackle the bombers while the more agile Spitfires held up the fighter escort. This ideal was not always achieved, however, and sometimes the Spitfires and Hurricanes reversed roles.Park also issued instructions to his units to engage in frontal attacks against the bombers, which were more vulnerable to such attacks. Again, in the environment of fast moving, three-dimensional air battles, few RAF fighter units were able to attack the bombers from head-on. During the battle, some commanders, notably Leigh-Mallory, proposed squadrons be formed into "Big Wings," consisting of at least three squadrons, to attack the enemy en masse, a method pioneered by Douglas Bader. Proponents of this tactic claimed interceptions in large numbers caused greater enemy losses while reducing their own casualties. Opponents pointed out the big wings would take too long to form up, and the strategy ran a greater risk of fighters being caught on the ground refuelling. The big wing idea also caused pilots to over-claim their kills, due to the confusion of a more intense battle zone. This led to the belief big wings were far more effective than they were. The issue caused intense friction between Park and Leigh-Mallory, as 12 Group were tasked with protecting 11 Group's airfields whilst Park's squadrons intercepted incoming raids. However, the delay in forming up Big Wings meant the formations often did not arrive at all or until after German bombers had hit 11 Group's airfields.Dowding, to highlight the problem of the Big Wing's performance, submitted a report compiled by Park to the Air Ministry on 15 November. In the report, he highlighted that during the period of 11 September – 31 October, the extensive use of the Big Wing had resulted in just 10 interceptions and one German aircraft destroyed, but his report was ignored.Postwar analysis agrees Dowding and Park's approach was best for 11 Group. Dowding's removal from his post in November 1940 has been blamed on this struggle between Park and Leigh-Mallory's daylight strategy. However, the intensive raids and destruction wrought during the Blitz also damaged Dowding and Park in particular, for the failure to produce an effective night-fighter defence system, something for which the influential Leigh-Mallory had long criticised them. Bomber and Coastal Command contributions Bomber Command and Coastal Command aircraft flew offensive sorties against targets in Germany and France during the battle. After the initial disasters of the war, with Vickers Wellington bombers shot down in large numbers attacking Wilhelmshaven and the slaughter of the Fairey Battle squadrons sent to France, it became clear that Bomber Command would have to operate mainly at night to achieve any results without incurring very high losses.From 15 May 1940, a night time bomber campaign was launched against the German oil industry, communications, and forests/crops, mainly in the Ruhr area. As the threat mounted, Bomber Command changed targeting priority on 3 June 1940 to attack the German aircraft industry. On 4 July, the Air Ministry gave Bomber Command orders to attack ports and shipping. By September, the buildup of invasion barges in the Channel ports had become a top priority target.On 7 September, the government issued a warning that the invasion could be expected within the next few days and that night, Bomber Command attacked the Channel ports and supply dumps. On 13 September, they carried out another large raid on the Channel ports, sinking 80 large barges in the port of Ostend.84 barges were sunk in Dunkirk after another raid on 17 September and by 19 September, almost 200 barges had been sunk.The loss of these barges may have contributed to Hitler's decision to postpone Operation Sealion indefinitely.The success of these raids was in part because the Germans had few Freya radar stations set up in France, so that air defences of the French harbours were not nearly as good as the air defences over Germany; Bomber Command had directed some 60% of its strength against the Channel ports. The Bristol Blenheim units also raided German-occupied airfields throughout July to December 1940, both during daylight hours and at night. Although most of these raids were unproductive, there were some successes; on 1 August, five out of 12 Blenheims sent to attack Haamstede and Evere (Brussels) were able to bomb, destroying or heavily damaging three Bf 109s of II./JG 27 and apparently killing a Staffelkapitän identified as a Hauptmann Albrecht von Ankum-Frank. Two other 109s were claimed by Blenheim gunners.[129][nb 19] Another successful raid on Haamstede was made by a single Blenheim on 7 August which destroyed one 109 of 4./JG 54, heavily damaged another and caused lighter damage to four more. There were some missions which produced an almost 100% casualty rate amongst the Blenheims; one such operation was mounted on 13 August 1940 against a Luftwaffe airfield near Aalborg in north-eastern Denmark by 12 aircraft of 82 Squadron. One Blenheim returned early (the pilot was later charged and due to appear before a court martial, but was killed on another operation), the other 11, which reached Denmark, were shot down, five by flak and six by Bf 109s. Of the 33 crewmen who took part in the attack, 20 were killed and 13 captured. As well as the bombing operations, Blenheim-equipped units had been formed to carry out long-range strategic reconnaissance missions over Germany and German-occupied territories. In this role, the Blenheims again proved to be too slow and vulnerable against Luftwaffe fighters, and they took constant casualties. Coastal Command directed its attention towards the protection of British shipping, and the destruction of enemy shipping. As invasion became more likely, it participated in the strikes on French harbours and airfields, laying mines, and mounting numerous reconnaissance missions over the enemy-held coast. In all, some 9,180 sorties were flown by bombers from July to October 1940. Although this was much less than the 80,000 sorties flown by fighters, bomber crews suffered about half the total number of casualties borne by their fighter colleagues. The bomber contribution was therefore much more dangerous on a loss-per-sortie comparison. It is a testament to the courage of the men in these bomber, reconnaissance and Coastal Command units that they continued to operate throughout these months with little respite and with little of the publicity accorded to Fighter Command. In his famous 20 August speech about "The Few", praising Fighter Command, Churchill also made a point to mention Bomber Command's contribution, adding that bombers were even then striking back at Germany; this part of the speech is often overlooked.The Battle of Britain Chapel in Westminster Abbey lists in a Roll of Honour 718 Bomber Command crew members, and 280 from Coastal Command who were killed between 10 July and 31 October .

1 June - 12 August 1940	German Luftwaffe forces concentrate efforts on maintaining control over the vital shipping lanes of the North Sea. At least 30,000 merchant ships are destroyed during this period.
16 July 1940	Hitler delivers Fuhrer Directive 17 as Operation Sea Lion - the land invasion of the British mainland to occur between September 19th and September 26th.
12 August 1940	The first attacks on RAF airfields and radar stations are conducted by German fighters and bombers. Germany intends on destroying RAF air supremacy before attempting its land invasion.
13 August 1940	At least 40 total Luftwaffe aircraft are destroyed by the RAF and ground-based flak teams. Southampton is heavily bombed by the German Luftwaffe. Andover is heavily bombed by the German Luftwaffe. Portland is heavily bombed by the German Luftwaffe. "Eagle Day" is enacted - a four day bombardment of key RAF airfields and radar installations. Poor weather initially delays the assault and any bombing thereafter produces mixed results.
15 August 1940	74 Luftwaffe aircraft launched from bases in Denmark and Norway are lost on what will be remembered as "Black Thursday".
17 August 1940	The RAF is forced to poach the ranks of Bomber Command in an effort to fill its dwindling supply of capable fighter pilots.
19 - 24 August 1940	Underestimating overall RAF fighter strength, Luftwaffe commander Hermann Goering changes offensive tactics and orders his fighters to tempt RAF fighters to duke it out in the skies as opposed to bombing them while still on the ground. Poor weather and overcast skies limit any major German bombing efforts over Britain.
24 - 31 August 1940	Luftwaffe bombing resumes. During this period, RAF airfields are hammered with the loss of 200 fighters. However, losses for the Luftwaffe number some 330 aircraft.
3 September 1940	Due to consistent Luftwaffe losses and inconclusive results across the entire campaign, Hitler postpones Operation Sea Lion to September 21st.
7 September 1940	348 bombers and 617 fighters of the German Luftwaffe descend on the British capital city of London in a massive bombing raid. In an effort to break the resolve of the British people, Hitler orders the bombing of London over the bombing of strategic RAF airfields and installations.
15 September 1940	Two massive bombing raids are conducted against Britain. The German Luftwaffe sees some 300 total RAF fighters airborne, showcasing Goering's gross estimate of total RAF air power. 80 German aircraft are lost in total. This day would go on to become "Battle of Britain Day".
16 September 1940	The German Luftwaffe redirects it sbombing campaign to now cover night-bombing of British cities.
17 September 1940	With the unexpected results of his campaign against Britain, Hitler officially postpones Operation Sea Lion indefinitely.