Designed as the logical replacement for the DH-4, The DH-9 never completely lived up to its anticipated billing.

The DH-9's airframe was simpler, quicker to build, and apparently would have improved performance over the DH-4. However, never ending engine problems plagued this aircraft until the wars end.

Even the designer, Jeoffrey De Havilland, writing to the Air Board warned that the performance of the DH-9 would be inferior to that of the DH-4. The biggest issue was the aircraft's lack of power to carry a bomb load at more than 15000' altitude. None of the engines chosen that would fit the airframe were reliable and/or predictable enough to provide the needed horsepower. Regrettably the Air Board locked in production on the DH-9 notwithstanding.

Incredibly, announcing that operational choices were: The Siddeley Puma powered DH-9 or nothing! Nevertheless there were pilots who preferred the DH-9 over the DH-4. When obliged to fight the DH-9 gave a good account of itself. The back to back position of pilot and gunner ensured maximum cooperation. After dropping its bomb load it was possible to tight turn a D-VII into a power stall and beat the Hun at his own game.  One rear gunner from No. 49 Sqd., E. Simpson, accounted for four attacking German aircraft on one mission.

Production commenced in Jan. 1918 and by war's end over 4000 DH-9 aircraft were completed. Twenty six RAF bomb squadrons were assigned DH-9s serving on the Western Front, in the Middle East,Macedonia, and Russia.