Stokes mortar

Trench mortar of World War I invented by Sir Wilfrid Stokes 1915; it is the prototype of every mortar designed since.

It consisted of a smooth-bore steel barrel with a closed end, resting upon a baseplate and held up at about 45° by a bipod. A screw mechanism allowed the barrel to be adjusted for angles of elevation. It fired a simple cylindrical bomb with a perforated tube at the rear end into which a shotgun cartridge filled with powder was fitted. The bomb was dropped down the barrel to strike a firing pin fixed at the base; this ignited the shotgun cartridge and the explosion of the powder ejected the bomb. The first bombs weighed about 9 kg/20 lb and had a range of about 900 km/1,000 yds; later bombs were lighter and had a greater range.