United Ireland

Ireland map; Republic of Ireland, Northern Ireland and their respective capitals

Satellite image of Ireland, nicknamed "The Emerald Isle"

United Ireland (Irish: Éire Aontaithe), also referred to as Irish reunification^[1][2][3] or a New Ireland,^{[4][5][6][7][8]} is the proposition that all of the island of Ireland should be a single sovereign state.^[9][10] At present, the island is divided politically: the sovereign state of Ireland (legally described also as the Republic of Ireland) has jurisdiction over the majority of Ireland, while Northern Ireland, which lies entirely within (but consists of only 6 of 9 counties of) the Irish province of Ulster, is part of the United Kingdom. Achieving a united Ireland is a central tenet of Irish nationalism and Republicanism, particularly of both mainstream and dissident republican political and paramilitary organisations.^[11] Unionists support Northern Ireland remaining part of the United Kingdom and oppose Irish unification.^[12][13]

Ireland has been partitioned since May 1921, when the implementation of the Government of Ireland Act 1920 created the states of Southern Ireland and Northern Ireland within the United Kingdom, with the former becoming independent, and the other petitioning to remain a part of the UK. The Anglo-Irish Treaty, which led to the establishment in December 1922 of a dominion called the Irish Free State, recognised partition, but this was opposed by anti-Treaty republicans. When the anti-Treaty Fianna Fáil party came to power in the 1930s, it adopted a new constitution which claimed sovereignty over the entire island. The Irish Republican Army (IRA) had a united Ireland as its goal during the conflict with British security forces and loyalist paramilitaries from the 1960s to the 1990s known as The Troubles. The Good Friday Agreement signed in 1998, which ended the conflict, acknowledged the legitimacy of the desire for a united Ireland, while declaring that it could be achieved only with the consent of a majority of the people of both jurisdictions on the island, and providing a mechanism for ascertaining this in certain circumstances.

In 2016, Sinn Féin called for a referendum on a united Ireland following Brexit, the decision by the United Kingdom to leave the European Union (EU). The decision had increased the perceived likelihood of a united Ireland, in order to avoid the possible requirement for a hard border between Northern Ireland and the Republic of Ireland,^[14][15] though the imposition of a hard border has not, as yet, eventuated. Fine Gael Taoiseach Enda Kenny successfully negotiated that in the event of reunification, Northern Ireland will become part of the EU, just as East Germany was permitted to join the EU's predecessor institutions by reuniting with the rest of Germany after the fall of the Berlin Wall.^[16]

The majority of Ulster Protestants, almost half the population of Northern Ireland, favour continued union with Great Britain, and have done so historically. Four of the six counties have Irish Catholic majorities, and majorities voting for Irish nationalist parties,^[17][18] and Catholics have become the plurality in Northern Ireland as of 2021.^[19] The religious denominations of the citizens of Northern Ireland are only a guide to likely political preferences, as there are both Protestants who favour a united Ireland, and Catholics who support the union.^[20] Two surveys in 2011 identified a significant number of Catholics who favoured the continuation of the union without identifying themselves as unionists or British.^[21] In 2024, a survey showed supporters of the Union in the minority in Northern Ireland for the first time, at 48.6%, while supporters of Irish unity were 33.76%.^[22]