On his return to Britain he learnt to fly. After obtaining his pilot's license in December 1913, he joined the Royal Flying Corps. He was sent to France and in 1915 was promoted to commander of 16 Squadron.

After the Battle of the Somme, Dowding clashed with General Hugh Trenchard, the commander of the RFC, over the need to rest pilots exhausted by non-stop duty. As a result Dowding was sent back to Britain and although promoted to the rank of brigadier general, saw no more active service during the First World War.

Dowding now joined the recently created Royal Air Force and in 1929 was promoted to vice marshal and the following year joined the Air Council.

In 1933 Dowding was promoted to air marshal and was knighted the following year. As a member of the Air Council for Supply and Research, he concentrated on research and development and helped prepare the RAF for war. This included a design competition that led to the production of the Hawker Hurricane and the Supermarine Spitfire. He was also responsible for encouraging the development of radar that became operational in 1937.

Dowding took command of Fighter Command where he argued that the Air Ministry should concentrate on development of aircraft for the defence of Britain rather than producing a fleet of bombers. Aware that the RAF would struggle against the Luftwaffe, Dowding advised Neville Chamberlain to appease Adolf Hitler in an attempt to gain time to prepare the country for war.

In 1940 Dowding worked closely with Air Vice Marshal Keith Park, the commander of No. 11 Fighter Group, in covering the evacuation at Dunkirk. Although Dowding only had 200 planes at his disposal he managed to gain air superiority over the Luftwaffe. However, he was unwilling to sacrifice his pilots in what he considered to be a futile attempt to help Allied troops during the Western Offensive.

During the Battle of Britain Dowding was criticized by Air Vice Marshal William Sholto Douglas, assistant chief of air staff, and Air Vice Marshal Trafford Leigh-Mallory, for not being aggressive enough. Douglas took the view that RAF fighters should be sent out to meet the German planes before they reached Britain. Dowding rejected this strategy as being too dangerous and argued it would increase the number of pilots being killed.

Dowding was credited with winning the Battle of Britain and was awarded the Knight Grand Cross. His old adversary, Hugh Trenchard, also told him that he had been guilty of gravely underestimating him for 26 years.

However, Air Chief Marshal Charles Portal, the new chief of the air staff, had agreed with William Sholto Douglas in the dispute over tactics and in November 1941, and Dowding was encouraged to retire from his post. Douglas had the added satisfaction of taking over from Dowding as head of Fighter Command.

Dowding was now sent on special duty in the United States for the Ministry of Aircraft Production before retiring from the Royal Air Force in July, 1942. The following year he was honoured with a baronetcy.

In his retirement he published Many Mansions (1943), Lynchgate (1945), Twelve Legions of Angels (1946), God's Magic (1946) and The Dark Star (1951). Hugh Dowding died on 15th February, 1970.