Northern Ireland opts
The partition of Ireland (Irish: criochdheighilt na hEireann) was the division of the island of Ireland into two distinct territories, Northern Ireland, a part of the United Kingdom, and the now Republic of Ireland, an independent state. Partition occurred when the British Parliament passed the Government of Ireland Act 1920 creating Northern Ireland and what was then Southern Ireland. From 1801 to 1920 the whole island had formed a constituent country of the United Kingdom. Before then it was the separate Kingdom of Ireland.
The Act of 1920 was intended to create two self-governing territories within Ireland that remained within the UK. The Act also contained provisions for co-operation between the two territories and for the eventual reunification of Ireland. However, partition was reinforced in 1922 when what was intended to be Southern Ireland separated from the United Kingdom as the Irish Free State.
Since partition began, a key aspiration of Irish nationalists has been to bring about a united Ireland, with the whole island forming one independent state. This goal conflicts with that of unionists in Northern Ireland, whose objective is to remain part of the United Kingdom. The British and Irish governments have agreed, under the 1998 Belfast Agreement, that the status of Northern Ireland will not change without the consent of the majority there.
Plans for partition were drawn up by Westminster after the Ulster Volunteer Force (UVF) imported 25,000 rifles and three million rounds of ammunition from the German Empire in April 1914, as there were fears that passing the Home Rule Bill could start a fullscale civil war in Ulster. The Curragh incident had already caused Westminster to believe that the British army could not be trusted to carry out government orders in Ireland. The issue of partition was the main focus of discussion at the Buckingham Palace Conference, although at the time it was believed that all nine counties of Ulster would be partitioned. Westminster passed the Home Rule Bill on 18 September 1914 and it immediately received Royal assent, but its implementation was simultaneously postponed by a Suspensory Act due to the outbreak of World War I. Following the failed Easter Rising Westminster called the Irish Convention in an attempt to find a solution to the Irish Question, but it ended without agreement due to the Conscription Crisis of 1918. Meanwhile support for the republican movement had increased in Ireland due to the ongoing war in Europe and the Middle East. Irish republicans were further emboldened by successful revolutions in the Russian Empire, the German Empire and the Austro-Hungarian Empire.
Beginning (or resuming) on 21 January 1919, through the Irish War of Independence, Irish republicans attempted to force the secession of Ireland from the United Kingdom of Great Britain and Ireland. Meanwhile, Irish Unionists – most of whom lived in the north-east of the island – were just as determined to maintain the Union. Seeking perhaps to defuse the situation by introducing a variation of the Home Rule Act that had lapsed with the onset of the Great War, the British Government decided to establish two devolved administrations, dividing the island into two territories: Northern Ireland and Southern Ireland. The Government of Ireland Act 1920 entered into force on 3 May 1921 and provided that Northern Ireland would consist of the six north-eastern counties, while the remainder of the island would form Southern Ireland. It was intended that each jurisdiction would be granted home rule but remain within the United Kingdom. The Government of Southern Ireland received limited acceptance: the war continued until the two sides agreed a truce in July 1921, ending with the Anglo-Irish Treaty on 6 December 1921.
Exactly a year later on 6 December 1922, the Irish Free State seceded from the United Kingdom. The new state had the status of a dominion of the British Empire. The secession occurred in accordance with the Treaty, which was given legislative effect in the United Kingdom by the Irish Free State (Agreement) Act 1922.
Under the treaty, Northern Ireland was permitted to remain outside of the new Irish Free State, provided that the Parliament of Northern Ireland chose to do so. However, under the form of words agreed upon, the Irish Free State was regarded as temporarily including the whole island of Ireland, until Northern Ireland expressly chose whether to be included or not. Therefore, in strict legal terms, Northern Ireland left the United Kingdom for a brief period along with the rest of Ireland, but then chose to opt-out of the Free State and rejoin the Union. However this had no practical effect, because in the interim the powers of the Irish Free State to govern Northern Ireland were declared to be suspended for up to a month, and Northern Ireland continued to be administered as a part of the United Kingdom.
On 7 December 1922 the houses of the Parliament of Northern Ireland approved an address to King George V, requesting that its territory not be included in the Irish Free State. This was presented to the King the following day, and then entered into effect, in accordance with the provisions of Section 12 of the Irish Free State (Agreement) Act 1922.
Following independence the southern state gradually severed all remaining constitutional links with the United Kingdom of Great Britain and Northern Ireland and the British monarchy. In 1937 the Free State was renamed to "Ireland" (a reflection of the fact that the state then claimed sovereignty over the whole of the island). In 1949 the state was declared to be a republic, under the Republic of Ireland Act.