During World War I, Watson Watt volunteered for the war effort, working as a meteorologist at the Royal Aircraft Factory, Farnborough, and applying his knowledge of radio to locate thunderstorms that posed hazards to airmen. In 1916, he proposed the use of cathode ray oscilloscopes to record and display such information, a project that led to his development of cathode ray direction finders in the mid-1920s, by which date Watson Watt was superintendent of the Radio Research Station at Slough, part of the National Physical Laboratory.
In 1933, Watson Watt took over a new radio department in Teddington, where he elucidated the theoretical basis for radar, conducting early experiments in using radio waves to locate aircraft. By 1938, he was director of communications development in the Air Ministry, and in 1940, he was appointed scientific adviser on telecommunications to the Ministry of Aircraft Production.
Watson Watt's assorted inventions proved their worth in the Battle of Britain, which might have been lost without them, and made major contributions to the ultimate Allied victory. In 1938, Chain Home, a pioneering early-warning system of fixed radar stations, was installed along Britain's east coast, where incoming German aircraft might be expected, and the system was later refined to detect low-flying airplanes. Watson Watt also developed airborne interception radar for installation in aircraft, to allow them to locate other airplanes and also seaborne vessels; these proved invaluable in the Battle of the Atlantic. And he developed identification, friend or foe (IFF) devices that could distinguish between friendly and hostile aircraft and could be installed on antiaircraft artillery, as well as radio navigation for bomber airplanes, which greatly facilitated the massive Allied bombing raids on Germany and Japan. Britain shared these technological innovations with the United States, and they represented the most significant instance of reverse Lend-Lease, save perhaps for ultra intercepts.
Knighted in 1942, Watson-Watt received a substantial financial award from the British government after the war for his work on radar, as well as numerous other professional honors and prestigious appointments. He established a consulting firm and lived in Canada for some years before returning to Britain. He died in Inverness, Scotland, on 5 December 1973.
Clark, Ronald W. The Rise of the Boffins. London: Phoenix House, 1962.; Guerlac, Henry E. Radar in World War II. 2 vols. New York: American Institute of Physics, 1987.; Jones, R. V. The Wizard War: British Scientific Intelligence, 1939–1945. New York: Coward, McCann and Geoghegan, 1978.; Watson-Watt, Robert. Three Steps to Victory: A Personal Account by Radar's Greatest Pioneer. London: Odhams, 1957.; Watson-Watt, Robert. The Pulse of Radar: The Autobiography of Sir Robert Watson-Watt. New York: Dial, 1959.