The three inch Stokes Mortar was invented by Sir Wilfred Scott-Stokes of Ransome & Rapier of Ipswich, England in 1914 and came into regular front line service in early 1916. His design of both weapon and ammunition was ease to manufacture and to use in the field, maximum rate of fire is quoted as 30 rounds per minute but a rate of 6 to 10 rounds was more practical in battle.
The weapon has a 51 inch smooth bore barrel, 3 inches in diameter, mounted on a flat base plate with a bipod which was adjusted for range. The barrel, baseplate and bipod were separate units, allowing the weapon to be easily disassembled, moved and reassembled in the field. This was vital as
firing the weapon revealed it's location and rapidly drew etaliation from the enemy. For this reason the Trench Mortar Team's were unpopular with the infantry as the team would assemble, aim and fire the Stokes Mortar, disassemble it and move possition, leaving the infantry in that area vulnerable to return fire from the enemy.
The mortar round or shell was a tube filled with 11lbs of high-explosive, fitted with an impact fuse at each end. The round was fired by means of a shotgun type cartridge which struck a fixed firing pin at the base of the barrel and ignighted propellant rings attached to the shell. Maximum range was about half a mile, range being determined by the elevation of the barrel and the amount of propellant used. The shell would explode on impact with the ground, sending shrapnell in all directions.