Ian Paisley and Martin McGuinness today promised to put hate in the past and formally pledged to lead a power-sharing government in a "new beginning" for Northern Ireland.
As the world watched, the veteran political foes joined forces as First Minister and Deputy First Minister to usher in a new era which Mr McGuinness said will involve a "fundamental change of approach".
Images which would have been viewed as unthinkable even a few years ago were being broadcast from Stormont across the globe as the new Executive was formed by the Assembly.
It took only 45 minutes for the 12 ministers and juniors to take the official pledge of office and bring about another attempt to make devolution work after five years of political turbulence and uncertainty.
Afterwards, in the Great Hall in Parliament Buildings, the new First Minister said: "From the depths of my heart I believe Northern Ireland has come to a time of peace, a time when hate will no longer rule."
The DUP leader said he had felt a great sense of relief from people who wanted to see hostility replaced by neighbourliness.
But he also said that if it had not been for the "interference" of some who claimed to have contributed to the political process, today's outcome could have been reached much earlier.
New Deputy First Minister Mr McGuinness spoke of the many victims over the four decades of the troubles and said: "We must look to the future and look for the means to help them heal."
Referring to the unique joint office he now shares with Mr Paisley, the former IRA second-in-command said: "I know this will not be easy and the road we are embarking on will have many twists and turns."
With behind the scenes negotiations continuing over an economic package for the new Executive, Mr McGuinness also appealed for the two governments to provide "the practical help we need".
There were jokes, too, as the newly-elected premiers of the province shared a cup of tea with the Irish and British Prime Ministers, who could both be out of office in the near future.
Mr Paisley quipped that a young man like Mr Blair was leaving office in his 50s while he, at 81, was coming into government.
The two long-opposed politicians were also watched from the public gallery by a range of people who helped put the peace process together and prevent it, at crucial points, from breaking down.
They included the church decommissioning witnesses, the Rev Harold Good, a former Methodist President, and Fr Alec Reid, whose involvement in the process stretches back for years, as well as one of the chief architects of the Good Friday Agreement, John Hume, and dignitaries including American senator Ted Kennedy.
Mr Blair said: "We can see the chance to begin to escape the heavy chains of history and make history anew."
He said many people had told him Mr Paisley would never agree to share power, but the DUP leader had told him in the right circumstances he would do what was necessary to see Northern Ireland at peace.
"I believed him and he has been true to his word," Mr Blair said.
Mr Ahern pledged that the Irish government would work with the Executive in the genuine spirit of partnership and friendship.
He said today had shown that divisions of the past can be put behind us and this should be the last generation to feel the anger of "old quarrels" .
Following the election of Mr Paisley and Mr McGuinness the party leaders nominated the Executive Ministers in turn - Peter Robinson as Minister of Finance and Personnel; Caitriona Ruane as Minister for Education; Nigel Dodds in Enterprise, Trade and Investment; Michael McGimpsey as Minister for Health; Margaret Ritchie as the Department of Social Development Minister; Conor Murphy as Minister of Regional Development; Arlene Foster as Environment Minister; Michelle Gildernew in Agriculture; Edwin Poots as Minister of Culture, Arts and Leisure and Sir Reg Empey as Minister of Employment and Learning.
The junior ministers who will work in the First Ministers' office, Ian Paisley Jnr and Gerry Kelly, were then appointed.
A DUP MLA was also elected as Speaker of the Assembly but Mr Paisley undertook that his party will support a Sinn Fein candidate to be the Speaker in the next Parliament.