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 the Orange Institution
The Fourth Home Rule Act was passed as the Government of Ireland Act 1920, the north eastern part of Ulster being partitioned from Southern Ireland as Northern Ireland. This new self-governing entity within the United Kingdom was confirmed under the terms of the Anglo-Irish Treaty of 1921. Southern Ireland became the Irish Free State in December 1922, then, in December 1937, it became Éire. This independent Irish state has been popularly known (in English) as the Republic of Ireland since it left the Commonwealth in April 1949.