In 1915 he joined the Royal Flying Corps and by 1937 he was an air vice-marshal and Director of Organization at the Air Ministry. In 1940 he was placed in charge of Bomber Command. The aircraft available had technical deficiencies, especially in navigation, but by carrying the bombing offensive into Germany, they disrupted munitions factories, power plants, and railway junctions. While introducing technical improvements, he pressed for a policy of “area bombing” to replace that of specific targets. After the war he became Controller of Atomic Energy in Britain (1945–51).