The Irish Republican Army (IRA) was a mass movement of young men, who willingly faced death, imprisonment or exile to achieve Irish independence. Though poorly armed and possessing few resources, the IRA dislocated Crown governance across much of Ireland and fought powerful Crown forces to a standstill from early 1920 to mid-1921.
The IRA built a sophisticated guerrilla army, based on a parish-by-parish organisation. A town, rural area, or urban neighbourhood/community formed a company; a number of companies comprised a battalion (usually a district, parliamentary constituency, or barony); a number of battalions formed a brigade (typically a large part of a county). Late in the War of Independence and during the Truce period, brigades were organised into divisions.
Overall, the IRA fielded a total 65 brigades and 297 battalions, with a paper strength of 115,550 Volunteers. Many Volunteers were nominal and not all units functioned adequately by the Truce of 1921. Yet, the IRA’s insurgency continued to grow despite severe pressure from the Crown forces. Read more about the IRA offensive against Royal Irish Constabulary in 1920 in this article by Dr John Borgonovo.
There are 2,184 IRA Companies listed in the IRA Nominal Roll files - an important series in the Military Service Pensions Collection available on the Military Archives website. These Nominal Rolls files were collected in the mid-1930s to assist in the awarding of pensions to people who were active during the War of Independence and the Civil War.