Fianna Fail and Fine Gael emerged following a split in nationalist opinion over the 1921 Anglo-Irish Treaty.

BBC: The Dail

Collins negotiated and signed the Anglo-Irish treaty in 1921, allowing six counties in the North to remain with Britain, as Northern Ireland.

BBC: The IRA's history of splits

With Cillian Murphy as a refined young rebel who wants complete separation from Great Britain and a socialist revolution in Ireland, and Padraic Delaney as his rough-hewn brother, who is willing to accept the Anglo-Irish Treaty of 1921.

NEWYORKER: The Wind That Shakes the Barley

One diplomat, a reliable and well-informed man from an important country, wondered to me today hypothetically but not very whether the Anglo-Saxon press was trying to doom the Irish referendum on the Lisbon Treaty this autumn.

ECONOMIST: European politics