Watson-Watt pioneered practical radar technology with the help of a brilliant team of engineers and physicists and support by a few men in the Royal Air Force and the British Air Ministry who could see the value of his work. They provided hope in 1935 that at least some bombers could be prevented from penetrating the aerial defences of Britain. The original name in use at the time was R.D.F which Watson-Watt thought German Intelligence might misinterpret as meaning “Radio Direction Finding”. Radar was originally coined in the USA in 1944 and later Watson-Watt suggested that this term should be accepted for general use.

In the early thirties, the general public were fearful of aerial attacks upon British cities using poison gas as well as high explosive. There appeared to be no defence against aerial attack on the major cities. A contemporary film based upon H.G. Wells book “Shape of Things to Come” gave graphic details of the effect of such attacks on city dwellers and greatly increased the fears.

As a result, the general public became alarmed at what they saw as a defenceless Britain, and this general concern forced the Air Ministry to form a committee headed by Professor Tizard to study all ideas which could provide a more effective defence system. Early in 1935, R. Watson-Watt was asked by H.E Wimperis, Director of Research at the Air Ministry and member of this committee, to give his views on the use of' “death rays” against bombers. Watson-Watt thought little of “death rays” but suggested it might be possible to detect the approach of bombers using radio. Simple tests suggested this indeed could be possible. The proposed system would avoid the necessity for fighters to maintain standing patrols over coastal Britain thus reducing wear upon the precious fighter aircraft with their pilots and ground crew.

After a simple test, it was seen that his ideas had merit and should be followed up. As a result, Air Marshall Hugh Dowding, the Air Staff member for Research and Development persuaded the Air Ministry and the British Treasury to invest an initial £150,000 in the ideas put forward by Watson-Watt. In July 1936 he became Air Officer Commanding Fighter Command and based upon the early work with Watson-Watt, re-organised the fighter air defences before the outbreak of war to incorporate fighter control by radar.

As the research carried by Watson-Watt’s team proceeded at Bawdsey Manor, Suffolk other potential applications were discovered and these were set aside in his “ice box” awaiting both future demand and resources to develop them. Diluting resources with further projects would only have served to delay progress on the main project.

Bomber Command had planned that on the outbreak of War the German Naval facilities at Wilhelmshaven and the warships moored there would be bombed to limit interference of surface and submarine raiders on the ships bringing vital supplies to Britain. The German fighters quickly proved that Bomber Command aircraft were defensively inadequate against German fighters and it was also not realised for some time that embryo German radar was used to warn of the approach of the British Bombers.

Bomber Command aircraft were hurriedly switched to bombing by night when it was thought darkness would provide more protection. Bomber Command had commenced operations on the basis of inadequate pre-war training in navigation by night and little research into new navigational devices required. With the towns and villages of Britain beneath them fully illuminated beneath them adequate training for operations by night was not possible.

The pilot had his blind flying panel and the observer/navigator, his Mercator charts and hand computer to work out courses and tracks. If a clear sky was visible above him he could use his aircraft sextant. Close to base he could seek a radio direction bearing but this would increase his vulnerability to detection and attack. These direction finding D/F bearings had to be computed separately for each aircraft and the system was as a result, often overloaded. Dead reckoning navigation (D.R.) was based on a triangle of forces whereby if the compass course is plotted together with the wind speed and direction the path of the aircraft can be calculated.

Accurate navigation by D.R. was dependent upon a true wind direction and speed for the height and area he was flying in. On some missions considerable evasive action would take place which would further complicate navigation. At the end of a two hour flight he could easily be a hundred miles off track. All lights in the towns and villages of Europe were extinguished and only in moonlight were rivers and coastal areas visible. The ability of bomber air crews to locate accurately targets in inland Europe using the technologies of the time was almost impossible.

These problems came to a head when in August 1941 Professor F.A. Lindemann examined flash photographs taken to coincide with release of bombs from a bomber. Too often he could see that they were exploding harmlessly in fields below. The result was that D.M. Butt, a member of Lindeman's secretariat in the Cabinet Office was instructed to prepare a detailed report which appeared in August 1941. This showed amongst other things, that only 10% of bomber aircraft had penetrated to within 10 miles of the target.

Bomber Command were critical of the report, and claimed that the picture it painted was inaccurate and too gloomy. Lindemann recognised that the weakness lay in poor navigation techniques and stressed to Churchill the need for change since it represented a major waste of British aircrews and industrial resources. Churchill demanded immediate action to improve standards of navigation.

Watson-Watt, had earlier been made aware that the poor standards of navigation were the major cause of Bomber Command being ineffective. He and his team had earlier recalled that R.J. Dippy, one of his research workers, had put forward in 1937 a scheme to form a grid of pulsed radio signals close to a bomber base, which would enable aircraft to locate and land in conditions of bad visibility.

In 1937, the scheme had been placed in the “ice box” for future development and had almost been forgotten. Dippy raised again the proposal of 1937 adding that his system could be extended to provide accurate position fixing over a wide area of Europe. This was not strictly a radar system, but it contained elements, which resembled it. Churchill with the Butt report before him, took action to ensure that a greater priority was placed on the development of this work.

The solution was to lay over Europe an invisible grid of GEE position lines which extended approximately 250 miles across Europe. This included the Low Countries and the vital Ruhr area of Germany. Transmitting accurately timed formed the grid and synchronised radio pulses from GEE stations, erected at Daventry, Ventnor, and Stenigot Hill.

These signals were received on special radio sets in the aircraft, which for the first time incorporated cathode ray tubes.

The fact that these sets received signals rather than transmitting them avoided the betrayal of the aircraft’s position to the Germans. There would be no limit to the number of aircraft using the system at any one time. The system was accurate in time and space and would allow for the marshalling of large bomber forces.

The GEE set enabled the differences between the times of arrival of the pulses from the neighbouring Gee stations to be measured and displayed to an observer. Should the GEE set record that the pulses from these two stations arrived simultaneously then the aircraft must be equidistant from the two stations and a straight line known as a position line be drawn on a map such that every point on it was a possible position for the aircraft. If the time differences could be drawn using one of the pair plus the third one another set of position lines could be drawn and the two position lines should intersect showing aircraft position at a given time.

The probable error of the system was calculated to be as little as 165 yards in the vicinity of the airfield, whilst on targets at the extreme edge of the grid this might increase to as much as one or two miles.

The Germans had devised before the war a beam system named Knickebein, and later X-Gerät which were navigational and bombing aids in finding and bombing targets. Once located, British scientists easily jammed them. The Germans having this system, thought it unnecessary to train their bomber crews in navigation.

The first conference on GEE was held at the Air Ministry on the 16th October 1940. This was followed by Air Marshall Pierce, the then A.O.C. Bomber Command, writing to the Ministry, recommending the provision of GEE as part of the standard equipment of his bombers.

As a result, a number of prototype sets were built in the spring of 1941 to enable them to be installed in 115 Squadron of 3 Command. Concern that these sets should be destroyed in the event of capture by the Germans lead to the requirement that detonators be fitted to these sets to destroy them in the event of aircraft being shot down. Later, it appears this instruction was overlooked, and development was considerably delayed pending their development.

In October 1940 a Signals officer and a Navigation officer from Bomber Command visited the dedicated research establishment at Worth Matravers. By June 1941, the first three navigators from the squadron were selected and trained and they in turn instructed other members of their flight. In August, the first flights were made entirely on Gee over the North Sea without any use being made of W/T.

The submission of the Butt Report led to even greater urgency being placed on the introduction of GEE. A R.D.F. (GEE) Chain Executive Committee was set up under the Chairmanship of Sir Robert Renwick in October 1941 to ensure the system entered service efficiently and as quickly as possible.

The first three special high powered radio stations were designed, built, and tested along with associated equipment.

The use of GEE enabled the navigator to calculate easily the wind direction and speed, en route and over the target. This facility aided assisted navigation, and if the bomb aimer was using the MkXlV bombsight, greatly improved the accuracy of the bombing. The navigator was able to obtain many more accurate fixes and was less dependent upon loop bearings and map reading by others.

The first operational trial of the new GEE took place on the night of 11-12th August 1941 when aircraft of 115 Squadron attacked Mönchengladbach railway sidings. The force was guided to the cloud obscured target by three GEE equipped Wellingtons, one of which was shot down. These special Wellingtons were used with the permission of Bomber Command, but without authorisation of the Air Staff. It was thus feared that an examination of the wreckage by the Germans would disclose the existence of GEE; a system, that was not scheduled to come into full use before 1942.

Next night, the two GEE-equipped Wellingtons, guiding 76 other Wellingtons, successfully found and bombed Hanover. Four Wellingtons, including one of the GEE-equipped aircraft, failed to return. Fortunately, the secret equipment was destroyed either by accident or design and the technical details did not fall into German hands.

The loss of these special aircraft, was of considerable concern to the Chief of Air Staff (C.A.S) who then decided to suspend all further operational, testing and training of the GEE system.

Tizard at the express request of Portal called a meeting to see what could be done to preserve the secrets of GEE. Tizard in turn consulted Dr R.V. Jones who was the leading scientist attached to MI6. The first step was to have the use of the term GEE abolished except for the system as a whole, and then to change all type numbers to T.R.1335 which might mislead German intelligence into believing that they were a group of standard telecommunication receivers. Finally the GEE stations were hurriedly disguised to resemble ordinary radar stations complete with mock masts etc. The GEE stations were allowed to operate but the element of emitting precise synchronisation of their pulses was deleted. The deception worked and the secret of GEE was preserved.

The question of preserving the secrecy of GEE was the subject of much top level discussion in 1941. To operate the GEE system it was necessary that lattice charts would have to taken into the air on operations. Prof F.A. Lindemann now Lord Cherwell said at one meeting that if the Germans captured an intact GEE receiver then it would take only a month for them to work out its secret function but a captured chart would take them less than a day. However Bomber Harris (later known as Sir Arthur) felt the political situation justified the use of GEE as soon as possible. No. 1418 Flight, the development unit for GEE did try to develop a method of using GEE without the use of charts but found its value was considerably reduced.

A Short History of

"GEE" Air Navigation


Copyright: Henry Black, 2001


Update: January 2008


Note: I am sadden to advise that Mr. Black has passed away. His articles are left in tribute to his historical research. May he rest in peace

On the 26th August an Air Ministry decision was taken to fit GEE onto all Wellington Mk lll�s and all four engine bombers on the production line. Dynatron and Cossor manufacturing companies undertook production of GEE sets.

The date selected to commence operations using GEE was 1st January 1942 but this was later moved to 1st February due to delays in installing the systems into the bombers. As it was, operations commenced with only ten squadrons ready for operations.

Days before the operational debut of GEE a flare dropping trial exposed inaccuracies in the system imposed by the operating systems which in turn illuminated problems of inadequate telecommunications poor supervision and inadequate numbers of operators. As crews were losing confidence in the system the C in C suspended all GEE flying using it. Within 48 hours, the Air Ministry re-organised the ground stations and provided the additional telephonic links required.

The first large scale attempt to use the GEE navigational system took place on the night of March 8-9th March 1942 when over 200 aircraft, consisting of Wellingtons, Hampden’s, Stirling’s and Manchester’s attacked, Essen was one of the main centres of armament design and production. Industrial haze over the target led to the raid not being a success although the use of GEE enabled 33% of the bombers to reach the general area. Krupps, the principal target escaped bombing, but bombs did hit the southern areas of the city.

The first completely successful raid GEE-led took place on the 13/14th March 1942, when Cologne was bombed. The leading crews successfully illuminated the target with flares and incendiaries and the bombing was generally accurate. Bomber Command reckoned this attack was 5 times more effective than the earlier Cologne raid.

However, the early use of GEE proved to be disappointing due to the clever use by the Germans of decoy fires and the initial inexperience of the British aircrews. Watson-Watt in his book declared that both Guy Gibson and Cheshire were surprisingly “tepid” in their enthusiasm over the introduction of GEE.

The increasing use of GEE inevitably led to a GEE set falling into German hands. It was not surprising to the British but within five months of its operational début the Germans started to jam transmissions. This first took place during a raid on Essen on 4/5th August 1942. Due to severe icing conditions only 18 out of 38 aircraft were able to drop bombs in the Essen area. Four days later on the 9/10th August during a raid on Osnabrück, the jamming became more effective although the bombing was still held to be a success.

However, the British scientists soon came up with an anti-jamming device, which eradicated the problem.

It went on to be a successful navigational aid throughout the war years. With the increasing use of GEE, the role of raid leaders prior to the formation of Pathfinders became easier, but no less hazardous. Supported by GEE, the raid leaders, normally experienced crews from within the squadrons, flew ahead to illuminate and mark the targets for their colleagues using 4.5” Parachute Flares.

The success of GEE led to a change in policy in that sixty German cities within GEE range were selected for mass bombing using 1,600-1,800 tons of bombs per city.

GEE was the most widely installed radar or radar-like airborne equipment with the possible exception of I.F.F. (Identification, Friend or Foe.)

The first GEE chain provided cover over the Holland, Belgium, the German Ruhr and over South West France. Other chains were provided mainly for the sea reconnaissance and strike aircraft of Coastal Command operating over the South-Western, and Western coasts of Britain.

The system eventually was also employed starting in 1943 by the USAAF 8th, 9th, 12th and 13th Air Forces.

The Royal Navy started to install the system in their light surface craft, which would enable them to operate in any weather. The laying and sweeping of mines also became a GEE operation. It was also used extensively in the invasion of Europe. GEE was as also used in photo-reconnaissance Mosquitoes.

In the closing years it was supplemented by “G-H” a super GEE, which was a highly accurate blind-bombing system. From 1942 until the end of the war; it signalled the development and use of a wide range of radar equipment such as H2S and OBOE, which increased enormously the effectiveness of Allied Air Forces in the destruction of the German War Machine.