The Irish Republican Army (IRA; Irish: Óglaigh na hÉireann, lit. 'warriors of Ireland') of 1922–1969 was a sub-group of the original pre-1922 Irish Republican Army, characterised as the Anti-Treaty IRA for its opposition to the Anglo-Irish Treaty. It existed in various forms until 1969, when the IRA split again into the Provisional IRA and Official IRA.
The original Irish Republican Army fought a guerrilla war against British rule in Ireland in the Irish War of Independence between 1919 and 1921. The Anglo-Irish Treaty signed on 6 December 1921 ended this war by granting most of the island a great degree of independence, but with six counties in the north staying within the United Kingdom as the new jurisdiction of Northern Ireland.