The Battle of Britain (7 page)

Nazi Germany's depredations in Europe and Fascist Italy's aspirations in Africa were a warning of imminent war that would involve Britain. In 1934 the RAF Expansion Scheme was announced. The Service now numbered 52 squadrons. These would be increased to 75. In 1935, when Italy went to war with Abyssinia, Britain moved three flying boat, four fighter and five bomber squadrons from their home bases to Middle East airfields from which they could protect Egypt, East Africa and Sudan. In 1936, with Germany and Italy even more aggressively on the rampage and threatening to provoke a conflict that would engulf the whole of Europe and spill over into the rest of the world, the Air Ministry took steps to increase the strength of regular squadrons to 136. In addition, it introduced a new stand-by pool, the RAF Volunteer Reserve, which aimed to train 800 pilots a year.

In May 1936, the RAF was restructured into four Commands: Fighter, Bomber, Coastal and Training. Geographical Commands, embracing the whole gamut of air operations, were retained overseas.

Fighter Command, with Air Chief Marshal Sir Hugh Dowding as Commander-in-Chief, had its Headquarters in Stanmore, a North London suburb. His immediately previous appointment had been on the Air Council as Member for Research and Development, so he was well acquainted with radar, an indispensable asset in his new post. Dowding had, as a captain, commanded No. 9 Squadron – formerly the Wireless Squadron – in 1915, on the Western Front. In 1916, as a major, he commanded No. 16, a scout – as fighters were called – squadron. Later that year, as a lieutenant-colonel, he took over 9th Wing. After the war he was successively Director of Training at the Air Ministry, and Air Officer Commanding-in-Chief, Transjordan and Palestine, before rising to the Air Council.

The Commands were sub-divided into Groups. In Fighter Command, these were on a geographical basis, further divided into Sectors, each named after its main airfield.

By the time the Battle of Britain was fought, Winston Churchill was Prime Minister of the Coalition Government. Sir Archibald Sinclair, leader of the Liberals, who had been Second-in-Command of Churchill's battalion of the Royal Scots Fusiliers in World War I, was Secretary of State for Air. Air Chief Marshal Sir Cyril Newall, who, as a lieutenant-colonel, had commanded 9th Wing of the Royal Flying Corps, was Chief of Air Staff. During his three years and two months in the post, ending on 24 October 1940, he presided over the Service during the period of its most vigorous peacetime expansion. Marshal of the RAF Sir John Slessor described him as the ‘prime architect of the wartime Air Force'.

Dowding was the only one of the Command C-in-Cs appointed in 1936 who was still in office. His Groups were: No. 10, which began forming in January 1940 and was operational by the end of July, Headquarters at Box, Wiltshire; No. 11, Commanded by Air Vice Marshal (AVM) Keith Park, HQ Uxbridge, a London suburb; No. 12, Commanded by AVM Trafford Leigh-Mallory, HQ Watnall, Notts; No. 13, Commanded by AVM Richard E. Saul, HQ Newcastle-on-Tyne.

Bomber Command, under Air Chief Marshal (ACM) Sir Charles Portal, with Headquarters near High Wycombe, Bucks, was divided into Groups according to the type of aicraft they flew. The operational
Groups were: No. 1, equipped with Battles, Headquarters at Hucknall, Notts; No. 2, Blenheims, HQ Huntingdon; No. 3, Wellingtons, HQ Exning, near Newmarket; No. 4, Whitleys, HQ York; No. 5, Hampdens, HQ Grantham, Lincolnshire. The Operational Training Groups were No. 5, HQ Abingdon, and No. 7, HQ Brampton, Huntingdon. For convenience, the stations in each Group were situated in as close proximity as possible. Portal had joined No. 8 Squadron as an observer in 1915 before converting to pilot. From C-in-C Bomber Command he went to Air Ministry as Chief of Air Staff until the Armistice. A wise and competent commander, he exercised much influence over Churchill.

Coastal Command was under ACM Sir Frederick Bowhill, who had joined the Navy in 1904, obtained his pilot's licence in 1913 and entered the Royal Naval Air Service. With his understanding of naval needs, he was ideally fitted for his new post. His Command, which operated closely with the Navy, consisted of No. 15 Group, HQ Plymouth; No. 16, HQ Chatham; No. 17, HQ Gosport; No. 18, Pitreavie Castle, Scotland. None of these was related to any particular type of aircraft. Only No. 18 Group had any geographical connotation: its squadrons were all based in the north, mostly in Scotland and the Shetlands, with one in Iceland and two in Yorkshire.

Training Command had been split, in May 1940, into Technical Training and Flying Training Commands.

While Britain designed and built a wide variety of fighters and bombers in the two decades between the world wars, armament received scant attention. Most aircraft carried the rifle-calibre (.303 inch) Vickers gun of 1914–1918. The other RAF weapon, dating from 1916, was the American 0.3 inch Browning adapted for rimmed .303 ammunition. Fighters usually had two Vickers machine guns. The Gladiator, which entered squadron service in February 1937 and was the RAF's last biplane fighter, was the first to be armed with a battery of four machine guns: they were Brownings. Its immediate successor, the Mk I Hurricane, entered service in December 1937 with eight Brownings, as did the Mk I Spitfire when delivered to its first squadron in June 1938.

These measures were not accompanied by an equally rational training programme for fighter pilots. The individual combat techniques developed in World War I were discarded. Combat practice was reduced to six set attacks made in section, flight or squadron strength. Air-to-air firing
exercises were carried out on a drogue towed behind a comparatively slow aeroplane flying straight and level.

At the outbreak of World War II the RAF was highly efficient technically in both flying and maintaining its aircraft. It was experienced in the swift movement of squadrons from one country or continent to another. Among those who had served in World War I there reposed a substantial fund of expertise in full-scale war. In the Spitfire it had the world's best fighter and in the Hurricane another that was in many other respects better than the enemy's. But its numbers were comparatively small and its fighter combat training had been dangerously inflexible.

Numerical weakness was compensated for by possession of a unique adjunct to the country's defence: a chain of radar stations that gave early warning of air raids. The word ‘radar', standing for ‘radio direction and ranging', was coined by the Americans and adopted by the RAF in 1943. Originally, it was called ‘RDF', meaning ‘range and direction finding', which was also good security; the process was thought to be concerned solely with radio direction finding as an aircraft navigation aid, which attracted little curiosity.

Development was carried out during the 1930s and exceeded the expectation of the Air Defence Sub-Committee of the Committee for Imperial Defence. On September 16, 1935, these bodies agreed that a chain of radio detection stations should be established between the Tyne and Southampton, to the number of about 20. These were to constitute ‘Chain Home', referred to as ‘CH'.

The expected ranges at which these would detect aircraft were:

83 miles at 13,000ft (132km at 3,939m).

50 miles at 5,000ft (80km at 1,515m).

35 miles at 2,000ft (56km at 606m).

25 miles at 1,000ft (40km at 303m).

The original scheme envisaged a transmitting station every 20 miles (32km), alternate ones to have a receiver also. Each mast was to be not less than 200ft (60.6m) high, on land not less than 50ft (15m) above sea level and not more than two miles (3.2km) from the coast.

Range measurement by a transmitter-receiver station would fix an aircraft as lying in a certain circle. Measuring the time interval between the pulse transmitted by a neighbouring station would put the aircraft in a certain ellipse. Thus a transmitter-receiver with its two flanking transmitters could get a fix. Height finding was not to be introduced at first,
although the height of an aircraft at 7,000ft (2,121m) altitude and 15 miles (24km) range had been measured to within one degree's error in elevation (l,200ft/363m) by comparing signals received by two vertical aerials. In February 1936 the main experimental work was moved to Bawdsey, south of Orfordness, where a CH station was built. There, on March 13, a Hawker Hart was seen at a range of 75 miles (120km) at a height of 15,000ft (4,545m).

Trials in 1937 showed that most aircraft appearing in the observed area were reported with good accuracy up to 80 miles (128km); bearing was less reliable than range; height was good above 8,000ft (2,425m), unreliable below 5,000ft (1,515m). Estimates of the size of formations were not reliable. By the time the annual Home Defence Exercise was held in the summer of 1939, C-in-C Fighter Command Air Chief Marshal Sir Hugh Dowding reported: ‘The system worked extremely well, and although doubtless capable of improvements as a result of experience, may now be said to have settled down to an acceptable standard.' At Easter 1939, with the outbreak of war expected at any moment, the radar chain had begun continuous watch-keeping. The Germans were curious about the tall towers that had sprung up on the English coast. In May General Wolfgang Martini, Chief of Luftwaffe Signals, flew up the east coast in the airship
Graf Zeppelin
, which radar picked up and, by the size and slow speed of the response on the cathode ray tube, identified. In August the airship, without Martini aboard, made a second sortie that radar did not detect, but which was seen by people in Scotland and intercepted outside the three-mile (5km) limit by a section of Auxiliary Air Force fighters. Both espionage ventures were abortive, as the Germans' receivers picked up only a miscellany of confused noises that betrayed nothing about the existence of radar. Generalleutnant Adolf Galland has since revealed that right up to the Battle of Britain the Luftwaffe thought that the main purpose of the towers was the detection of shipping.

Chain Home operated on a wavelength of 10 to 13.5 metres, on frequencies of 22 to 30MHz, with 200kW peak power output. Its range was 120 miles (192km) and it could read height. The aerials were stationary, the transmitter was on a 350ft (106m) steel tower and the receiver on a 240ft (73m) wooden one. The coverage was described as ‘floodlight', i.e., it was diffused in a wide arc or complete circle, which both inhibited the obtaining of accuracy in azimuth and allowed low-flying aircraft to go undetected. A shorter wavelength was needed to pick
up at low altitude, and a rotating aerial to enable a narrow ‘searchlight' beam to sweep from side to side or be pointed in any required direction.

Such equipment was devised and formed the Chain Home Low, or CHL. Its wavelength was 1.5m, frequency 200MHz, and power output 150kW. Range was 50 miles (80km) and it could not read height. The aerial, adapted from 200MHZ gun-laying radar that had also been designed at Bawdsey, was a gantry 20ft (6m) high, mounted on a 185ft (56m) tower.

The first CHL station began operating in November 1939. Mobile units were also being built. The vehicles on and in which they were installed became known as a ‘convoy'. The wavelength was 5.4 to 10m, frequency 30-56MHz, power output 40kW, range 90 miles (144km) and it indicated target height. The combined CH and CHL system gave the RAF an excellent probability of detecting virtually any intruders.

At the time of the 1936 reorganisation, the main question for Fighter Command was how to make the best use of radar. A control and reporting system (in RAF parlance ‘C & R') had to be devised, to report the presence of enemy aircraft and control the movements of the fighters sent up to intercept them. Overall tactical control would be vested in Headquarters Fighter Command. Tactical control within each Group area would be delegated to Group Headquarters. Once fighters were airborne they would be controlled directly by their Sector. This meant that each Group and Sector, as well as HQ Fighter Command, had to have an Operations Room, in which the air activity within its area of responsibility could be shown. The general situation map (commonly referred to as the plotting table) in a Sector Ops Room needed to show the whole sector area and a large part of the adjacent sector or sectors. In a Group Ops Room, the whole Group area and part of the adjacent Group or Groups had to be displayed. In the Fighter Command Ops Room, a picture of the whole of the British Isles was necessary.

In addition to the CH stations, another source of information had to be integrated: the Observer Corps. This organisation originated in 1914 on the outbreak of World War I. The Royal Naval Air Service being responsible for home defence, the Police were instructed to report to the Admiralty by telephone when enemy aircraft were seen or heard. In 1916, the Army, of which the Royal Flying Corps was an arm, took over from the Admiralty. Cordons of civilian observers were now positioned at a radius of 30 miles (48km) around vulnerable areas, to inform the War
Office when they saw or heard enemy aircraft and, if possible, to give an estimate of course and height. In 1921 the Observer Corps was restructured into observation posts that reported to observation centres reporting in turn to Fighting Area HQ, which was responsible for the defence of Great Britain.

By the time the RAF was restructured in 1936, the Observer Corps had grown in numbers. It took over from radar the tracking by sound and sight, and reporting, of aircraft when they crossed inland over the coast. The Observer Corps was a body of mostly part-time civilian members. At the end of the war the accuracy of their estimations was assessed most commendably. Height: visual, average error 10 per cent up to 20,000ft (6,060m); sound, 20 per cent. Strength: visual, exact; sound, good.

With three systems (Chain Home, Chain Home Low and the Observer Corps) reporting aircraft movements, a means of resolving disparities and duplication had to be found. Filtering was the name given to this process. At Bawdsey, an experimental filter room was set up in July 1937, to sort out the plots passed by the three CH stations then operating – Bawdsey itself, Dover and Canewdon (Essex) – and telling the filtered plots through to the Ops Room at Fighter Command during the annual exercise in August. On November 8, 1938, this was closed and the Filter Room opened at HQ Fighter Command.