Cobham entered the Royal Flying Corps in 1917 and in 1921 joined Geoffrey de Havilland's new aircraft company, for which he undertook a succession of long-distance flights: 5,000 miles (8,000 km) around Europe; 8,000 miles (12,800 km) across Europe and North Africa; 12,000 miles (19,300 km) through Europe to Palestine, Egypt, along the North African coast, and back through Spain; to the Cape of Good Hope and back; to Australia and back. From 1926, the year in which he was knighted, he operated his own firm. For Imperial Airways he flew 23,000 miles (37,000 km) around Africa in 1927, and in 1931 he made a survey flight up the Nile River and across the Belgian Congo (now Congo 【Kinshasa】) for the Air Ministry. During the next four years his flying circus team of pilots toured Britain and gave many their first thrills of aerial display. He worked out a system for refueling aircraft from aerial tankers that was first used off Ireland in 1939. He wrote a number of books about his activities, including My Flight to the Cape and Back (1926) and Twenty Thousand Miles in a Flying Boat (1930). His memoirs, A Time to Fly, were edited by C. Derrick and published in 1978.