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.
History of Northern Ireland
Throughout this period, the main paramilitary organisations began to form. 1972 was the most violent year of the conflict. In 1970 the Provisional IRA, was created as a breakaway from what then became known as the Official IRA (the Provisionals came from various political perspectives, though most rejected the increasingly Marxist outlook of the Officials and were united in their rejection of the Official's view that physical force alone would not end partition), and a campaign of sectarian attacks by loyalist paramilitary groups like the Ulster Defence Association (formed to co-ordinate the various Loyalist vigilante groups that sprung up) and others brought Northern Ireland to the brink of civil war. On 30 March 1972, the British government, unwilling to grant the unionist Northern Ireland government more authoritarian special powers, and now convinced of its inability to restore order, pushed through emergency legislation that prorogued the Northern Ireland Parliament and introduced direct rule from London. In 1973 the British government dissolved the Parliament of Northern Ireland and its government under the Northern Ireland Constitution Act 1973.