[2] Having served as a cadet in the Officers' Training Corps, Firth was commissioned as a temporary second lieutenant on 29 August 1914.
45 Squadron RFC as a Sopwith 1 1/2 Strutter pilot, he scored his first win on 12 July 1917; he helped drive down a German Albatros D.III fighter out of control east of Messines.
[9][7] On the second day of the new year, Firth shared in the destruction of an enemy reconnaissance plane east of Conegliano and became a double ace.
[15] On 29 April 1919, he married Ruth Ellen [Eleanor], the daughter of Canon John Henry Hodgson, rector of Dogmersfield, Hants, at Winchester Cathedral.
[3] At the time of Firth's death on 23 August 1931, he was in business as a steel manufacturer and residing at Spital House, Blyth, Worksop, Nottingham.