David Trimble, a former first minister of Northern Ireland and Nobel Peace Prize winner, has died at the age of 77, the Ulster Unionist Party said Monday.

The party said in a statement on behalf of the Trimble family that the unionist politician died earlier Monday “following a short illness.”

Trimble, who led the UUP from 1995 to 2005, was a key architect of the 1998 Good Friday Agreement that ended three decades of violent conflict in Northern Ireland known as “The Troubles.”

Keir Starmer, leader of Britain’s opposition Labour Party, called Trimble “a towering figure of Northern Ireland and British politics” in a tweet Monday.

The UUP was Northern Ireland’s largest Protestant unionist party when, led by Trimble, it agreed to the Good Friday peace accord.

He was the party’s first leader in 30 years to meet with the Irish premier in Dublin. In 1997, Trimble became the first unionist leader to negotiate with Irish republican party Sinn Fein.

Trimble shared the 1998 Nobel Peace Prize with Catholic moderate leader John Hume, head of the Social Democratic and Labour Party, for their work.

He became first minister in Northern Ireland’s first power-sharing government the same year, with the SDLP’s Seamus Mallon as deputy first minister.

But both the UUP and the SDLP soon saw themselves eclipsed by more hardline parties – the Democratic Unionist Party and Sinn Fein.

Trimble struggled to keep his party together as the power-sharing government was rocked by disagreements over disarming the IRA and other paramilitary groups. Senior colleagues defected to the DUP, Trimble lost his seat in Britain’s Parliament in 2005 and soon after he resigned as party leader. The following year he was appointed to the upper chamber of Parliament, the House of Lords.

Northern Ireland power-sharing has gone through many crises since then – but the peace settlement has largely endured.

“The Good Friday Agreement is something which everybody in Northern Ireland has been able to agree with,” Trimble said earlier this year. “It doesn’t mean they agree with everything. There are aspects which some people thought were a mistake, but the basic thing is that this was agreed.”

Trimble is survived by his wife Daphne and children, Richard, Victoria, Nicholas and Sarah.