Okay - I see from a previous message you posted that Frederick Charles Boehmer was a Captain, this makes things a little easier and I was able to see from the 1885 Army List that he was commissioned in 1883.
Before that he was a Colour Sergeant in the 51st Foot (South Yorkshire) and did indeed serve in the Afghan war with that regiment - as Colour Sergeant 2494, and was awarded the Afghan war medal with clasp for Ali Masjid (ref. medal roll).
He became a Lieutenant in the Bedfordshire Regiment in Oct 1883 and in Jan 1887 he was seconded for service as Adjutant of the Madras Railway Volunteers; he was seconded for service as Adjutant in the East Indian Railway Volunteer Rifle Corps in Mar 1889 (ref. London Gazette).
The 1890 Army List shows that he became Captain in Mar 1889 and that he was at that time serving with the East Surreys. It also notes he served in the Jowaki campaign (India medal with Jowaki clasp) and the Afghan war (Afghan medal with Ali Musjid clasp), both with the 51st.
He was placed on temporary half-pay due to ill health in May 1896, and placed on retired pay Nov 1896 (ref. London Gazette).
The London Gazette of 7 Jan 1910 seems to indicate that he died 22 Oct 1909.
Hope that is of interest.
Best wishes -
Garen
P.S. Looking further ... it seems he was Agatha Christie's uncle?