page_title: Dowding system
section_title: Effects on the battle
hierarchical_section_title: Dowding system / Effects on the battle
caption_attribution_description: Deutsch: FuMG 41 "Freya LZ", verbunkert, Stützpunkt Lama Aufgenommen in Thyborön / Westjütland / Dänemark
context_page_description: The Dowding system was the world's first wide-area ground-controlled interception network, controlling the airspace across the United Kingdom from northern Scotland to the southern coast of England. It used a widespread dedicated land-line telephone network to rapidly collect information from Chain Home radar stations and the Royal Observer Corps in order to build a single image of the entire UK airspace and then direct defensive interceptor aircraft and anti-aircraft artillery against enemy targets. The system was built by the Royal Air Force just before the start of World War II, and proved decisive in the Battle of Britain.
  The Dowding system was developed after tests demonstrated problems relaying information to the fighters before it was out of date. Air Chief Marshal Hugh Dowding, commander of RAF Fighter Command, solved the problem through the use of hierarchical reporting chains. Information was sent to Fighter Command Headquarters central filter room at Bentley Priory and used to prepare a map of the battle. Details of the map were then relayed to the Group and Sector headquarters, where operators re-created the map at a scale covering their area of operations.
context_section_description: The effect of this system was profound, and remains a widely used example of the concept of force multiplication.
  Before the introduction of radar the task of interception appeared to be increasingly difficult, if not impossible. As bomber speeds and altitudes grew, the time available to arrange an interception was dropping. Although fighter performance was also increasing, certain aspects like getting the pilot into the aircraft and taking off introduced fixed delays that did not improve. With the only detection means being the observers and acoustic location with ranges on the order of 20 mi (32 km) under the very best conditions, the bombers would be over their targets before the spotters could call in the raid and the fighters could climb to their altitude.
  Given this lopsided balance of power, fighter operations prior to the introduction of radar were generally in the form of standing patrols or "sweeps", with the fighters being sent up to fly along a pre-arranged path or area in the hopes of encountering the enemy. During World War I interception missions, the vast majority of patrols returned home without ever having seen the enemy. The same was true for all forces during the Battle of France, where 30% interception rates were considered typical, and 50% excellent.
  In the case of an attack by a high-speed force, the attackers could pick the time and place of the attack. They would encounter only the aircraft already in the air along that route, so they could outnumber the defenders in any given area. To ensure there were a reasonable number of fighters along any approach route, huge numbers of aircraft would need to be in the air at all times covering all the routes. Since a fighter spends most of its time on the ground being maintained and refuelled, some multiple of the airborne numbers would be needed, along with a similarly huge number of pilots, as each pilot could only be expected to fly so long per day. Such a system was essentially impossible, and was one of the reasons it was widely believed that "the bomber will always get through".
  A startling illustration of this scenario was provided by the RAF itself. In the summer of 1934, a series of large-scale exercises with up to 350 aircraft were carried out. About half the number were bombers attempting to approach London, and the other half fighters trying to stop them. The initial results were so dismal that the commanders attempted to improve the results, eventually giving the fighter controllers complete details of the bomber's locations prior to the mission. Even then, 70% of the bombers reached London without having even seen a fighter. The result was, as one RAF commander put it, that "a feeling of defencelessness and dismay, or at all events of uneasiness, has seized the public."
  The unified view of the battlespace provided by the Dowding system turned the tables in favour of the defence. By rapidly sending accurate, timely information to the fighters, their ability to find and attack the enemy was dramatically increased, and the time required to do so decreased. The fighters took off, flew directly to their targets, engaged, and returned directly to their bases. In early operations interception rates of 75% were routine, and this number continued to improve as the operators became more familiar with their tasks. By the end of the Battle of Britain, rates of interception over 90% were becoming common, and several raids were met with 100% interception rates. In numerical terms, it was as if Fighter Command had over twice as many fighters, giving them effective parity with the Luftwaffe.
  While CH was being installed in the UK, the Germans were working on their own radar systems and had deployed an excellent early-warning system known as Freya. The complexity of relaying the information from the radars to the fighters had not been addressed and was apparently never seriously considered at the time. During the Battle of the Heligoland Bight in 1939, over 100 German aircraft were scrambled to meet a small force of RAF bombers, but less than half of these fo
caption: The German Freya early warning radar was a match for British units. Early detection alone was not enough, however; the information needed to be relayed to the pilots.
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