First World War
The DH.9A entered service in July 1918 with No. 110 Squadron RAF, moving to France on 31 August 1918 to serve with the RAF's Independent Air Force on strategic bombing missions. Its first mission was against a German airfield on 14 September 1918. A further three squadrons commenced operations over the Western Front before the Armistice, with 99 Squadron (also serving with the Independent Air Force) replacing DH.9s, while 18 Squadron and 216 Squadron replaced DH.4s. Despite the superior performance of the DH.9A over the DH.9, the DH.9A squadrons suffered high losses during their long range bombing missions over Germany. Other squadrons flew coastal patrols from Great Yarmouth before the end of the year.
The United States Marine Corps also adopted the DH.9A, its Northern Bombing Group receiving at least 53, operations starting in September 1918.
Interwar RAF service
While the squadrons in service at the end of the First World War quickly disbanded or re-equipped in the postwar dis-armament, the DH.9A continued in service as the RAF's standard light bomber, with a total of 24 squadrons being equipped between 1920 and 1931, both at home and abroad.
The first post war operations were in southern Russia in 1919, in support of the "White Army" against the Bolsheviks in the Russian Civil War. In September 1919, the RAF personnel were ordered to return home, leaving their aircraft behind. A squadron of DH.9As was deployed to Turkey in response to the Chanak Crisis in 1922, but did not engage in combat.
The DH.9A was one of the key weapons used by Britain to manage the territories that were in its control following the collapse of the Ottoman Empire at the end of the Great War. Five squadrons of DH.9As served in the Middle East, carrying out occasional bombing raids against rebelling tribesmen and villages. A larger radiator was fitted to cope with the high temperatures, while additional water containers and spares (including spare wheels lashed to the fuselage) were carried in case the aircraft were forced down in the desert, the DH.9A's struggling under ever heavier loads. Despite this it served successfully, with the Liberty engine being picked out for particular praise for its reliability ("as good as any Rolls Royce") in such harsh conditions. Some DH.9A aircraft were also transported to India to supplement the British Indian Army.
At home, the DH.9A continued on in regular RAF service until 1930, also forming the initial equipment of the Royal Auxiliary Air Force (RAuxAF).
The R-1 was heavily used by the Soviet Air Forces through the 1920s as its standard light bomber and reconnaissance aircraft. The Soviets deployed R-1s in support of the Chinese Kuomintang forces in the Northern Expedition against warlords in 1926–27 and against Chinese forces in clashes over control of the Chinese Eastern Railway in Manchuria in 1929. R-1s were also used in support of operations against Basmachi Rebels in central Asia.