British development of radar
The ability of radio to be used to detect reflections of transmitted electromagnetic radiation or radio waves was first demonstrated in 1904. It was developed to enable ships to maneuver more safely in ports in poor weather and at night.
During World War I, as aviation was starting to emerge, British engineer Robert Watson-Watt started work at the British Meteorological Office on efforts to detect thunderstorms by radio using the electrical discharge given off by lightning. This work led to the discovery that aircraft could be detected from the electromagnetic radiation (radio waves) reflecting from the metal parts of aircraft. In 1933, the British Air ministry determined that an improved means to detect approaching bombers was needed. Existing methods using simple visual observers or acoustic detection were not sufficient. The rapid rearmament of Germany, especially the development of German air forces, made this effort a priority.
Watson-Watt became superintendent of the Radio Department of the British National Physical Laboratory. In 1935, he proposed using radio detection methods to provide the needed new aircraft detection system. Within weeks of his proposal, he demonstrated the basic concept. After his radio detection proposal was selected over competing approaches, Watson-Watt was placed in charge of the engineering development of the system. The initial three coastal stations became operational in 1937, followed by 19 more by the time of the start of the “Battle of Britain” in 1940.
The rapid deployment of radar is given great credit for the Royal Air Force’s success during the Battle of Britain. Without the radar system and lacking sufficient fighters to mount an effective airborne warning, the antiquated methods of ground observers and acoustic detection of approaching bombers would not have provided sufficient warning time. Using the coastal radar early warning system, sufficient warning time was provided to enable fighter forces to scramble and achieve the necessary position and altitude to intercept incoming bombers. The Royal Air Force was, thus, able to make best use of its limited fighters and pilots to maintain a sufficiently effective air defense and deny Germany the air superiority over the English Channel and the British coast it needed to undertake its invasion of England.