Founded in 1905 to resist Home Rule, the UUP governed the north for generations. Maeve Connolly reports
THE UUP plays second fiddle to the DUP at Stormont with 13 members compared to the younger party's 38 yet for generations the UUP dominated Northern Ireland politics.
The party began life in 1905 as the Ulster Unionist Council. Before that there was an Irish Unionist Party but a separate Ulster Unionist Party emerged following the partition of Ireland with James Craig taking over the leadership from Edward Carson.
The UUP governed the north's devolved institutions from 1921 until 1972 and completely dominated politics as the sole major unionist party.
However, the first split occurred in the late 1960s with the formation of Ian Paisley's Protestant Unionist Party which began to attract hard-line supporters dissatisfied with the reformist leadership of Terence O'Neill.
The British government introduced direct rule in 1972 and unionism fragmented further.
The New Ulster Movement - which became the Alliance Party - removed the most liberal from the UUP while Paisley's political grouping took the hard-liners and the UUP was divided down pro and anti-Sunningdale Agreement lines.
Pro-Sunningdale leader Brian Faulkner - who became the final prime minister of Northern Ireland - did not enjoy a lengthy stay in the power-sharing assembly and after being over-thrown set up the Unionist Party of Northern Ireland (UPNI).
The UUP formed a coalition with the Vanguard and Democratic Unionists in the 1974 general elections and this United Ulster Unionist Coalition (UUUC) secured 11 out of a possible 12 Westminster seats.
Subsequently three unionist groupings, Faulkner's UPNI, the United Ulster Unionists Party (UUUP) and the Vanguard Party broke up while the UUP was known as the Official Unionist Party for most of the 1970s and 1980s.
James Molyneaux led the party between 1979 and 1995 and was succeeded by David Trimble whose support for the Good Friday Agreement divided both party and electorate.
Meanwhile, UUP member Bob McCartney set up the United Kingdom Unionist Party (UKUP) which won five seats in the Northern Ireland Forum but four elected members later left and formed the Northern Ireland Unionist Party (NIUP).
In 2005 the Orange Order voted to sever ties with the UUP and the full extent of voter anger was laid bare in that year's general elections when Trimble was defeated and all but one of the six MPs lost their seat.
In turn new leader Reg Empey tried to form a wider unionist assembly group involving the Progressive Unionist Party (PUP) but the move was not met with full support from his party.
Ahead of the last general election in 2010 the UUP announced its intention to field joint candidates with the Conservative Party under the Ulster Conservatives and Unionists - New Force (Ucunf) banner.
The UUP's only MP, Sylvia Hermon, opposed the deal and resigned from the party so from 2010 the UUP has been without representation in the House of Commons for the first time since the party's creation.
Sir Reg Empey resigned and his replacement, Tom Elliott, was dealt a further blow when three Westminster election candidates resigned.
Mr Elliott himself stepped down in 2012 to be replaced by Mike Nesbitt with many commentators suggesting he may be the party's final leader.