"During the 1914-1918 War, The Royal Dublin Fusiliers recruited nine extra battalions,some of which were held in reserve in Britain against the threat of an invasion should The Allies be defeated by the Axis Powers on the mainland of Europe. The 3rd. Reserve Battalion, 4th. Extra Reserve Battalion and 5th. Extra Reserve Battalion were formed from the old 3rd., 4th, and 5th. Militia Battalions respectively."
3rd Bn: Formerly the Kildare Militia Rifles. Staff HQ at Nass.
4th Bn: Formerly the Royal Dublin City Militia (Queen's Own Royal Regiment). Staff HQ at Dublin.
5th Bn: Formerly the Dublin County light Infantry Militia. Staff HQ at Dublin.