Ulster Unionist Party

The Ulster Unionist Party (UUP) is a unionist political party in Northern Ireland. The UUP is the third oldest political party in the United Kingdom, and the oldest political party on the island of Ireland. The party was founded as the Ulster Unionist Council in 1905, emerging from the Irish Unionist Alliance in Ulster. Under Sir Edward Carson, it led unionist opposition to the Irish Home Rule movement. Following the partition of Ireland, it was the governing party of Northern Ireland between 1921 and 1972. It was supported by most unionist voters throughout the conflict known as the Troubles, during which time it was often referred to as the Official Unionist Party (OUP).

Under David Trimble, the party helped negotiate the Good Friday Agreement of 1998, which ended the conflict. Trimble served as the first First Minister of Northern Ireland from 1998 to 2002. However, it was overtaken as the largest unionist party in 2003 by the Democratic Unionist Party (DUP). As of 2022 it is the fourth-largest party in the Northern Ireland Assembly, after Sinn Féin, the DUP, and the Alliance Party. Since August 2024 the party has been led by Mike Nesbitt.

Between 1905 and 1972, its peers and MPs took the Conservative Party whip at Westminster, in effect functioning as the Northern Irish branch of the party. This arrangement came to an end in 1972 over disagreements over the Sunningdale Agreement. The two parties have remained institutionally separate ever since, with the exception of the 2009 to 2012 Ulster Conservatives and Unionists electoral alliance. The first-ever membership survey of the UUP, published in January 2019, suggested that 67% of its members were supportive of the Conservative Party.

The Ulster Unionist Party traces its formal existence back to the foundation of the Ulster Unionist Council in 1905. It is the oldest political party on the island of Ireland.

Modern organised unionism emerged after William Ewart Gladstone's introduction in 1886 of the first of three Home Rule Bills in response to demands by the Irish Parliamentary Party. In 1891, the Irish Conservative Party came to an end, merged into a new Irish Unionist Alliance (IUA) which also included the Irish Liberal Unionists, the latter having split from the Liberal Party over the issue of home rule. While usually dominated by unionists from Ulster, the IUA was often led by southern unionists. There were also some eighty members of the House of Lords who affiliated themselves with the IUA.

The Ulster Defence Union was also formed on 17 March 1893 to oppose the Liberal government's plans for the Government of Ireland Bill 1893.

Although most unionist support was based in Ulster, especially within areas that later became Northern Ireland, in the late 19th and early 20th century there were unionist enclaves throughout all of Ireland. Unionists in Dublin and County Wicklow and in parts of County Cork were particularly influential.

In September 1904, the Conservative government of Arthur Balfour published proposals for limited devolution to Ireland which would not amount to home rule. Coming from Conservatives, these led to great alarm among Irish unionists; in March 1905, the Ulster Unionist Council, which later became the Ulster Unionist Party, was formed as a co-ordinating organization for a new form of local political activity. It largely subsumed the Ulster Defence Union.