Personnel of the Saskatoon Light Infantry firing mortar in the vicinity of Ortona, Italy, 5 January 1944. From left to right, Privates Bill Park, Andy Jannock, Joe Armstrong, and Corporal Alex Buchanan. Photo by Alexander M. Stirton. Department of National Defence / National Archives of Canada, PA-116845.

During the Second World War, mortars were used by infantry for immediate support. Smooth-bore weapons which projected "bombs" over short distances at high trajectories (greater than 45 degrees), mortars basically consisted of an inclined barrel mounted on a baseplate which channelled the recoil shock into the ground, supported by a bi-pod or tri-pod. Mortar bombs usually had fins to stabilize their flight, and had the propellant charge fixed to the tail end. To fire, the bomb was simply dropped into the barrel, the propellant charge being ignited upon contact with a firing pin at the base.

The British and Canadian armies used three types of mortars: