The Troubles
The Government of Ireland Act 1920 partitioned the island of Ireland into two separate jurisdictions, Southern Ireland and Northern Ireland, both devolved regions of the United Kingdom. This partition of Ireland was confirmed when the Parliament of Northern Ireland exercised its right in December 1922 under the Anglo-Irish Treaty of 1921 to ""opt out"" of the newly established Irish Free State. A part of the treaty signed in 1922 mandated that a boundary commission would sit to decide where the frontier of the northern state would be in relation to its southern neighbour. After the Irish Civil War of 1922–1923, this part of the treaty was given less priority by the new Dublin government led by W. T. Cosgrave, and was quietly dropped. As counties Fermanagh and Tyrone and border areas of Londonderry, Armagh, and Down were mainly nationalist, the Irish Boundary Commission could reduce Northern Ireland to four counties or less.
Northern Ireland
Northern Ireland was created in 1921, when Ireland was partitioned between Northern Ireland and Southern Ireland by the Government of Ireland Act 1920. Unlike Southern Ireland, which would become the Irish Free State in 1922, the majority of Northern Ireland's population were unionists, who wanted to remain within the United Kingdom. Most of these were the Protestant descendants of colonists from Great Britain. However, a significant minority, mostly Catholics, were nationalists who wanted a united Ireland independent of British rule. Today, the former generally see themselves as British and the latter generally see themselves as Irish, while a distinct Northern Irish or Ulster identity is claimed both by a large minority of Catholics and Protestants and by many of those who are non-aligned.