Active service unit

An active service unit (ASU; Irish: aonad seirbhíse cogúla)[1][2] was a Provisional Irish Republican Army (IRA) cell of four to ten members, tasked with carrying out armed attacks.[3] In 2002, the IRA had about 1,000 active members of which about 300 were in active service units.[4]

Active service unit at a 1981 hunger strikes commemoration in Galbally, County Tyrone, 2009, as part of a re-enactment. The weapons are a Beretta AR70, a MAC-10 machine pistol (with sound suppressor) and an AK-47 assault rifle.
Wall plaque in Great Denmark Street, Dublin where the 1919 IRA Active Service Unit of the Dublin Brigade was founded. Every Brigade had[citation needed] an Active Service Unit; these were[citation needed] also called "Flying Columns."

The name “Active Service Unit” dates from the War of Independence as the official army name of the “Flying Columns” to distinguish between Volunteers who acted as support troops versus those “on the run” and actively involved in military attacks.

In 1977, the IRA moved away from the larger conventional military organisational principle owing to its perceived security vulnerability. In place of the battalion structures, a system of two parallel types of unit within an IRA Brigade was introduced. Firstly, the old "company" structures were used to supply auxiliary members for support activities such as intelligence-gathering, acting as lookouts or moving weapons.[5]

The bulk of attacks from 1977 onwards were the responsibility of a second type of unit, the ASU. To improve security and operational capacity these ASUs were smaller, tight-knit cells, usually consisting of five to eight members, for carrying out armed attacks. The ASU's weapons were controlled by a quartermaster under the direct control of the IRA leadership.[6] By the late 1980s and early 1990s, it was estimated that the IRA had roughly 300 members in ASUs and approximately 450 serving in supporting roles.[7]

The exception to this reorganisation was the South Armagh Brigade which retained its traditional hierarchy and battalion structure and used relatively large numbers of volunteers in its actions.[8] Some operations, like the attack on Cloghogue checkpoint or the South Armagh sniper squads, involved as many as 20 volunteers, most of them in supporting roles.[9]

The smaller Republican paramilitary organisation the INLA also used the term "active service unit,[10] as did the Loyalist paramilitary groups the Ulster Volunteer Force[11] and Ulster Defence Association.[citation needed]

See alsoEdit


  1. ^ "Achtanna Den Oireachtas a Ritheadh Sa Bhlia[i]n ...: 1937". Stationery Office. 8 March 1937 – via Google Books.
  2. ^ "Ní Neart go cur le Chéile | An Phoblacht".
  3. ^ Leahy, Thomas (2020). The Intelligence War against the IRA. Cambridge University Press. p. 89. ISBN 978-1108487504.
  4. ^ Moloney, Ed (2002). A Secret History of the IRA. Penguin Books. pp. xiv. ISBN 0-14-101041-X.
  5. ^ O'Hearn, page 19
  6. ^ Bowyer Bell Page 437
  7. ^ O'Brien, p.161
  8. ^ Moloney, p.377
  9. ^ Harnden, Toby (2000). Bandit Country:The IRA and South Armagh. Coronet books. pp. 404. ISBN 0-340-71737-8.
  10. ^ "Archived copy" (PDF). Archived from the original on 26 February 2019. Retrieved 16 August 2020.{{cite web}}: CS1 maint: archived copy as title (link) CS1 maint: bot: original URL status unknown (link)
  11. ^ "Statement by the Ulster Volunteer Force (UVF), (3 May 2007)". CAIN. Retrieved 11 August 2020.