The COW 37 mm gun was a British automatic cannon that was developed during First World War as a large-calibre aircraft weapon.
The tests did not yield satisfactory results and the weapon did not enter general service except on a few flying boats.
Coventry Ordnance Works had been set up in 1905 by a consortium of British shipbuilding firms (John Brown, Cammell Laird and Fairfield) to compete with the duopoly of Vickers and Armstrong-Whitworth in producing naval guns.
The gun was ready to produce only as the First World War came to an end and was only in service briefly, having been fitted to a pair of Airco DH4s.
[4] After the war it was used in a number of different aircraft, mostly flying boats such as the Blackburn Perth, where it was seen as being effective against small vessels.