Irish Republican Army (1922–69)

Irish Republican Army (Óglaigh na hÉireann)
Participant in Irish Civil War and the Troubles
Active	March 1922–December 1969
Leaders	IRA Army Council
Area of operations	Ireland United Kingdom
Strength	14,500 (at maximum) 1,000 (at minimum)
Originated as	Irish Republican Army
Became	Provisional IRA, Official IRA
Opponents	United Kingdom, Irish Free State
Battles and wars	Irish Civil War (1922–1923) IRA Sabotage Campaign (1939–1940) IRA Northern Campaign (1940–1942) IRA Border Campaign (1956–1962) the Troubles (1966–1969)

The original Irish Republican Army (IRA) fought a guerrilla war against British rule in Ireland in the Irish War of Independence between 1919 and 1921. Following the signing of the Anglo-Irish Treaty on 6 December 1921, the IRA in the 26 counties that were to become the Irish Free State split between supporters and opponents of the Treaty. The anti-Treatyites, sometimes referred to by Free State forces as Irregulars, continued to use the name Irish Republican Army (IRA) or in Irish Óglaigh na hÉireann, as did the organisation in Northern Ireland which originally supported the pro-Treaty side (if not the Treaty).Óglaigh na hÉireann was also adopted as the name of the pro-Treaty National Army, and remains the official legal title of the Irish Defence Forces. This article deals with the anti-Treaty IRA that fought the Irish Civil War and with its successors up to 1969, when the IRA split again.

The signing of the Anglo-Irish Treaty by the Irish delegation in London caused an angry reaction among the less compromising elements in Sinn Féin and among a majority of the IRA. Dáil Éireann ratified the Treaty by 64 votes to 57 after a lengthy and acrimonious debate, following which President Éamon de Valera resigned. Sinn Féin split between pro-Treaty and anti-Treaty factions, and the Army followed suit. The majority of headquarters staff, many of whom were close to Michael Collins, supported the Treaty, but opinion among IRA volunteers was divided. By and large, IRA units in Munster and most of Connacht were opposed to the Treaty, while those in favour predominated in the Midlands, Leinster and Ulster. The pro-Treaty volunteers formed the nucleus of the new National Army.

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