No, it didn't cease to exist in 1921, the Military Service Pensions Act 1934 passed by the Dáil recognises military service in the Irish Republican Army which it describes as Óglaigh na hÉireann (Irish Republican Army) to differenciate it from Óglaigh na hÉireann, which was being used by the Irish Defence Forces. This would mean that the Irish State recognised the existance of the Irish Republican Army for at least two years after 1921. Most impartial observers recognise that the Irish Republican Army as an organisation, by which I mean as a body which continued on, continued to exist until the split between the Official and Provisional IRA. It may be fashionable now in Ireland to deny this but those who fought the Civil War on both sides had little doubt about the fact that the organisation which fought against the treaty did not disapear but continued on. The purpose of the Military Pensions Act was bring as many of the members of the IRA into non-violent Freestate political life as possible. Mark Jones