Single-engined bomber of the RFC and then RAF. Designed to replace the Airco DH 4 and entered service late 1917 and on ops from March 1918.
However, since its AS Puma engine was notoriously unreliable it proved to be inferior to the DH 4, but since it was in full production before flight testing revealed its shortcomings the RFC / RAF were stuck with it.
Only when the a/c was redesigned around the American Liberty engine and became the DH 9A was it worth having.