I don't know if this counts as army, navy or airforce. In 1917 the no 1 squadron Australian Flying Corps took the fuselage of a Martinsyde 101 'Elephant' long range fighter/bomber and mounted it on some fort of raft or float (a bit like those things used in the Florida Everglades I suspect) and used it to intercept dhows attempting to run supplies to the Turkish army at night through the shallows at the top of the Red Sea . Does anyone in this forum have more information? How was it armed? Did it carry a search light? etc etc.
Thanks - as usual with these things this answers many questions only to pose some new ones. The book on No 1 Sqnd AFC actually said Red but this must be a typo/missprint or the like. The fuselage in your photo is definitely an Elephant but the floats look as if they've come off a Sopwith Baby - one wonders how the Australians came by these. I still wonder how they armed the thing - the Elephant normally caaried one or two Lewises - one over the top wiing and one on for rearward defence on a swivel behind the pilot (which he had to be a contortionist to use). Neither appear to be fitted - there was no interrupter gear. I'm sure they couldn't have relied on the fear factor alone.
Searching on 'Martinsyde' turned up the same picture as the one in the article and mention of another, but nothing else. The article text mentions that the pilot fired to the rear which must have been fun trying to control something unstable!