Engineering Hitler's Downfall. Gwilym Roberts

      Radar

      1935 Radio Research Station (RRS) scientists detect radio waves reflected from an aircraft 25 km distant. Government authorises further investigations.

      1936 RRS moves to country house near Felixstowe, Essex.

      1939 Chain of radar transmitting and receiving towers around the coast from the Solent to the Tay Estuary operational.

      Dowding system for interpreting information received and controlling aircraft movements also operational.

      1940 Chain extended to cover southwestern and western coastlines.

      Battle of Britain (BoB)

      1933 Air Ministry issues specification for new fighter aircraft.

      Designing Supermarine Spitfire and Hawker Hurricane fighters gets underway.

      Rolls-Royce conduct first test run of Merlin aero-engine.

      1937–38 First deliveries of Hurricanes and Spitfires to RAF.

      1940 Dowding commander in chief of Fighter Command and Park in charge of No. 11 Group covering South East England.

      10 Jul BoB commences with Luftwaffe sweeping over SE England but with RAF conserving resources.

      1 Aug Hitler orders Luftwaffe ‘to destroy the British air force’.

      8 Aug Luftwaffe begins attacks on RAF bases. RAF engages enemy.

      15 Aug Main Luftwaffe attack repulsed by RAF.

      Operation Sealion for invasion of UK postponed.

      24 Aug Start of daytime raids on London

      31 Oct BoB ends.

      Nov, Dec Dowding succeeded by Sholto Douglas and Park by Leigh-Mallory.

      THE BLITZ

      7 Sep Day and night raids begin on London and South East England and continue for the next 57 days.

      1 Nov Luftwaffe initiates concentrated night raids on London, ports and industrial targets (the Blitz).

      14 Nov Major raid on Coventry.

      1941 Night fighters fitted with AI radar.

      1–7 May Major raids on Liverpool and Merseyside.

      May Blitz ends as Luftwaffe units withdrawn in readiness for invasion of Russia.

       Chapter 4

      RADAR, BATTLES IN THE AIR, AND THE BLITZ

      Victories followed by survival

      Winston Churchill memorably eulogised the brave pilots who fought the Battle of Britain, and so saved the nation, in those crucial make-or-break months from July to October 1940: ‘Never in the field of human conflict was so much owed by so many to so few.’

      The Prime Minister well knew, however, that it was an invisible but immensely powerful engineering development, which was no less significant than those celebrated dog-fight heroics, that had made the epic victory possible.

      ‘The RAF’s Hurricanes and Spitfires were handicapped by clumsy tactical doctrine and .303 machine-gun armament with inadequate destructive power,’ Max Hastings wrote in All Hell Let Loose, ‘but squadrons were controlled by the most sophisticated radar, ground-observer and voice-radio network in the world, created by an inspired group of civil servants, scientists and airmen.’

      With radar, he added, ‘the RAF had developed a remarkable system of defence, while their opponents had no credible system of attack.’

      That alleged German weakness would not have been apparent to most Britons in the days and months after the Dunkirk evacuation. By mid-1940 the British and French armies had been defeated in Norway and France, and Norway, Denmark, the Low Countries and the northern and western coastal areas of France had been occupied. Therefore, Germany was able to base her aircraft, U-boats, and surface vessels along the whole continental coastline from northern Norway to the Franco-Spanish border.

      Britain had thus became vulnerable to short-range aerial attack and possible invasion while the German Navy had easy access to the North Atlantic and could more easily attack the merchant vessels supplying Britain with her essential imports of food, fuel and armaments.

      The country was in the gravest peril, though the population was resolutely behind the Government and faced the prospect with equanimity. Their attitude was well summarised by the reputed remarks of a West End club porter who said, ‘Well, sir, we’ve made the final and, what’s more, we are playing at home!’

      Proving Baldwin Wrong

      During the inter-war years the conventional wisdom, forcibly expressed by the then-Prime Minister, Stanley Baldwin, had been that there was no defence against aerial attack other than having a greater force than the enemy.

      ‘It is well also for the man in the street to realise,’ he told Parliament in 1932, ‘that there is no power on earth that can prevent him from being bombed. Whatever people may tell him, the bomber will always get through. The only defence is in offence, which means that you have to kill more women and children more quickly than the enemy if you want to save yourselves.’

      Enter the engineers!

      While the RAF concentrated most of its research and development efforts on Bomber Command, to the detriment of aerial defence and Fighter Command (and, to an even greater extent, maritime warfare and Coastal Command), brains were already at work on the kind of defensive shield Baldwin had been unable to imagine.

      It was thought possible, for example, that the noise made by aircraft might be used to detect their direction and range, and experimental acoustic mirrors were erected around the coast, some of which are still standing. Measuring up to 70 metres wide and 5 metres high, they were made of concrete to spherical, not parabolic, concave shapes and had a microphone near the focal points which could be moved so as to determine the aircraft’s direction. While partially successful, they became less effective with increasing aircraft speed and were abandoned when electronic systems were developed.

      Following discussions between Sir Henry Tizard, the chairman of the Aeronautical Research Committee, and Robert Watson-Watt, the superintendent of the radio research station then based at Slough, Berkshire, Watson-Watt investigated the feasibility of developing and using damaging radiation – commonly known as ‘death rays’ – as a defence. He concluded that they would not damage the crew or equipment inside a metal aircraft, which would in effect act as a Faraday cage (a mesh of conductive material around a person or object which shields the contents from external electromagnetic fields).

      However, his assistant, Arnold (Skip) Wilkins, suggested that it might be possible to detect an aircraft by bouncing radio waves off it. Following experiments using radio waves generated by the BBC shortwave transmitter at Daventry, in February 1935 they were able to detect an RAF bomber at a distance of 12 km. This was the first time that this had been achieved in Britain and the event is now commemorated by a plaque at Stowe Nine Churches, Northamptonshire.

      Acoustic mirrors, Denge, Kent. © Paul Russon

      Commemorative Plaque, Stowe Nine Churches, Northamptonshire. Peter Mallows

      Wilkins, Arnold (‘Skip’) OBE (1907–1985)

      Educated at the universities of Manchester