Mapping IRA Companies, July 1921-July 1922

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.

For the purpose of the Military Service Pensions Acts, two Critical Dates were defined:

  • First Critical Date: 11th July 1921
  • Second Critical Date: 11 July 1922

The First Critical date marks the end of the War of Independence. The Second Critical Date marks the start of the Civil War when the IRA occupying the Four Courts in Dublin surrendered to the National Army.The IRA Nominal Roll files list the number of people who were active in IRA Companies on the First Critical Date and on the Second Critical Date.

Now, for the first time, UCC in collaboration with the Military Archives, bring you an interactive story map providing details of each IRA Company between the end of the War of Independence and the beginning of the Civil War


The interactive map was designed and produced by Charlie Roche (MobileGIS, associated cartographer/researcher for University College Cork’s Atlas of the Irish Revolution) based on an original map created by Mike Murphy, editor of the Atlas of the Irish Revolution. Steve Smyth software engineer with MobileGiS provided key technical support.

 Click here to view the map in full screen.


Public Webinar: Mapping IRA Companies, 1921-22

Watch a webinar about the background and construction of the interactive IRA Companies Map here

Find Out More

The Irish Revolution Project

Scoil na Staire /Tíreolaíocht

University College Cork, Cork,