The 3" mortar was the standard medium mortar of British forces during World war 2. When first issued the ammunition was short ranged compared to similar weapons, improved propellant charges became available in 1943 which gave a substantial increase to range. The 3" mortar remained in service with British forces into the 1960's.

In 1940, 12 of these mortars went overseas with the artillery of the 6th Division 2nd AIF. 2/10th and 2/15th Field Artillery Regiments with the 8th Division were initially partially issued 3 inch mortars 2/15th conducted all its training in Malaya with them. Once sufficient guns became available the mortars were withdrawn from service with the artillery but were used extensively by the infantry in New Guinea and the Islands.