PROFILE: Since the DUP's emergence in the November 2003 Assembly Election as the strongest voice in unionism, it has been hard to escape the impression that David Trimble was biding his time as leader of the Ulster Unionists.
The turning point came in January last year, when Mr Trimble's chief rival in the Ulster Unionists, Jeffrey Donaldson defected to the DUP along with two Assembly colleagues, Arlene Foster and Norah Beare.
Mr Donaldson, the MP for Lagan Valley, had fought and lost a gruelling six year battle against David Trimble to change party policy.
The UUP leader was wrong, he believed, to take republicans on trust and enter into government with Sinn Fein three times without full IRA arms decommissioning.
Over time, the battle got more and more personal.
In an emotional parting shot in Stormont's marble Great Hall, Jeffrey Donaldson told how Trimbleistas had ordered him and his two Assembly colleagues to toe the party line or face expulsion.
"I have never been at a meeting like that meeting of the party executive that day," he said.
Under David Trimble's leadership, Jeffrey Donaldson, a former aide to Enoch Powell and Lord (Jim) Molyneaux, claimed the Ulster Unionists were no longer the party of traditional unionist values.
But he wasn't always regarded that way.
David Trimble cut his political teeth an angry young unionist during the 1970s, emerging through the ranks of Bill Craig's Vanguard Unionist Party.
The party, which he would become deputy leader of, opposed power sharing involving Ulster Unionists, nationalist SDLP and cross-community Alliance Party ministers.
Almost three decades later, he would sit in government as First Minister with Paisleyite unionists, the SDLP and Sinn Fein.
The Queen's University Belfast law lecturer was elected in 1975 as a Vanguard Unionist in South Belfast in elections for the Northern Ireland convention but when the party collapsed three years later, he switched allegiances to the Ulster Unionists.
It would be 12 years before he would emerge as a frontline player in the party.
The death of Upper Bann MP Harold McCusker in 1990 saw him catapulted into the constituency.
A strong by-election victory marked him out as a formidable force in the party and within five years he captured the leadership of the UUP following the decision of Jim (now Lord) Molyneaux to stand down in the wake of the 1994 IRA and loyalist ceasefires.
His election was a surprise. UUP veteran John Taylor, now Lord Kilclooney, had been the favourite.
However David Trimble established his traditional unionist credentials during the 1995 Drumcree marching dispute between Portadown Orangemen and nationalist residents in the Garvaghy Road.
At the end of the stand-off, with Orangemen marching down the Garvaghy Road he joined the Rev Ian Paisley on a victory parade, raising their hands triumphantly.
The image angered nationalists but held out the prospect to unionists that their two parties would stand shoulder to shoulder in the uncertain days of the IRA ceasefire.
In the House of Commons, David Trimble proved an effective operator - propping up Prime Minister John Major's Government while bringing the destruction of IRA weapons to the fore as an issue effecting negotiations with Sinn Fein.
IRA frustration at the slow pace of political progress saw the collapse of the first ceasefire with the Canary Wharf bomb in London in February 1996.
The Provisionals reinstated their ceasefire in 1997 following Prime Minister Tony Blair's election victory, posing the first real challenge for David Trimble as Sinn Fein claimed its place in talks at Stormont.
While the DUP and UK Unionists walked out of talks, the UUP remained, insisting they would fight the corner for unionism.
The second challenge came in the final hours of talks leading to the Belfast Agreement, when Mr Trimble came under intense pressure to sign up to a deal which promised power-sharing government but also allowed for the early release of IRA and loyalist paramilitary prisoners.
Jeffrey Donaldson and a posse of young unionists could not stomach it, walking out of the negotiations and creating the hairline fracture which the UUP would never heal.
Mr Trimble's pragmatism was rewarded in 1998 when he shared the Nobel Peace Prize with the SDLP's John Hume.
However in the months following the Agreement, he also showed caution - initially refusing to immediately rush into government with Sinn Fein without some move on IRA disarmament.
In November 1999, David Trimble took another gamble - persuading his party despite opposition from Jeffrey Donaldson and others - to go into government with Sinn Fein on the understanding that IRA weapons decommissioning would follow.
When that did not materialise, he forced the then Northern Ireland Secretary Peter Mandelson to suspend the Stormont executive, establishing a pattern of stop start devolved government every time he wanted to force movement from the IRA.
The IRA's decision on October 2001 to finally embark on decommissioning, in the wake of the horrific 9/11 Al Qaeda terror attacks in the United States, was viewed by the Ulster Unionist leader as a personal vindication of everything he had fought for.
"This is the day we were told would never happen. This is the day we were told we would never see," he triumphantly declared. However every gamble David Trimble took was not rewarded at the ballot box.
In the 2001 General Election, there was evidence the DUP was making clear inroads into the UUP's grip on unionism as East Londonderry, Strangford and North Belfast fell into the party's hands.
Mr Trimble also faced a recount in his Upper Bann constituency, where it was estimated tactical support from around 1,600 Catholic voters gave him a 2,058 majority over the then little known gospel singer and meat trader David Simpson - a DUP candidate who would claim his scalp four years later.
The 2003 Assembly Election was the watershed moment in his battle with the DUP - the time when the party could no longer sustain its internal divisions or maintain its grasp on unionism with its much criticised `Simply British' advertising campaign.
Having had easy access to Downing Street, the White House and the corridors of power as Northern Ireland First Minister and UUP leader, David Trimble found himself an increasingly marginalised figure as the Democratic Unionists assumed the lead role in unionism in negotiations featuring Sinn Fein.
"David Trimble's been an electoral liability for us for some time," one Assembly colleague caustically remarked as Mr Trimble slipped to defeat in Upper Bann.
"The longer he stays, the worse it gets. He's not comfortable on the ground and has no feel for what unionist voters want. It's time to draw a line under the Trimble era and find a way to rebuild this party from the ruins."
PA