"He fought with the Old IRA"
3rd Tipperary Brigade IRA 1921
Public Domain3rd Tipperary Brigade IRA 1921

Referred to as the "Old" IRA (Irish Republican Army) to distinguish the original group from others which have since claimed to be members of the IRA.  They were formed in 1919 to fight for an Irish socialist republic, to include Ulster.


Further Reading:

Northern Divisions: The Old IRA and the Belfast Pogroms (1920-22) by Jim McDermott