The 18-pounder was introduced to the Irish National Army in 1922 on the foundation of the state. It was first used by National Army Gunners to bombard the Four Courts in Dublin from 28 June 1922, as part of the Battle of Dublin. The departing British Forces were criticised for the lack of training that they had imparted to the gunners of the infant Irish artillery corps, and for providing shells intended to destroy barbed wire rather than the normal HE shells. The marks of the shell fire can still be seen on the walls of the Four Courts. The 18-pounder played an important role throughout the Irish Civil War, being instrumental in the fighting in Munster alongside the Rolls-Royce Armoured Car. The nine 18-pounder guns were used in the infantry support role until grouped together to form an artillery corps in March 1923.