Church leaders and two delegations, one from the Orangemen and one from Catholic residents, had gathered at 9am in the offices of Ulster Carpets, at the end of the Catholic Garvaghy Road.
Two senior churchmen - the Primate of Ireland, Archbishop Dr Robin Eames, and the Catholic primate Cardinal Cahal Daly - hoped to broker a last- minute deal to appease both sides over the marching route.
For more than two hours, Protestants and Catholics sat in separate rooms as churchmen shuttled between them, desperately looking for agreement. None came, and by 11.30am RUC Land-Rovers were already moving into the Garvaghy area.
At 11.45am, the RUC Chief Constable, Sir Hugh Annesley, took a call from church leaders to say the negotiations had failed. Within minutes, fearing people could die if the stand-off continued, he ordered that the march should go ahead through the Catholic area.
Rumours had swept both communities late on Wednesday that the end, negotiated or otherwise, was imminent. But when it came, its swiftness took a disbelieving Catholic community by surprise. A hastily arranged sit-in by 300 residents on the main marching route was forcibly removed by baton-wielding RUC officers who fired rounds of plastic bullets when they were challenged.
Claire Digim watched in horror. "They fired more rounds in 20 minutes at us than in four days at the Orangemen - and they were aiming for us."
Soldiers moved in to roll away barbed wire and up to 1,500 Portadown District Lodge members walked through four-abreast at 12.47pm.
"Keep your heads up", shouted supporters as the group, led by the Star of David Accordion Band, made up mainly of young girls, began to march.
There was no mood of celebration at this point, but within five minutes the mood electrified as the parade moved past Catholic houses.
One resident surveyed the marchers and said: "I have voted for the SDLP all my life, but now Sinn Fein will definitely get my vote. We're just second class citizens - white niggers."
The violence flared quickly. A group of youths, some in masks to hide their faces, pelted officers with stones and bottles from Churchill Road, and let off four petrol bombs. Police retaliated with baton rounds.
The Orangemen marched on with no sound, except the steady beat of a single drum.
But by the time the parade reached the Protestant area of Park Road, they were joined by thousands from other lodges who looked back and shouted and jeered at the Catholics. "This is a victory for us," said one. "Maybe the RUC will think twice before they ban it again."
The whole parade took just 23 minutes - but it left indelible scars for the locals. Oonagh Burke, 23, said: "We're leaving now and moving to the south or to a safer Catholic area. We just don't have any rights any more.
Youths from the estate were now in full-scale conflict with the RUC; four cars were set on fire, and missiles and fireworks descended on the officers.
Father Eamon Stack, who had been in the earlier negotiations, condemned the "heavy-handed" police tactics. "We have lost a great opportunity," he said. A local community leader, Brendan MacCionnaith, also at the talks, added: "We have been stitched up. Hopes of peace were batoned away in Garvaghy Road."
In heavy rain, the centre of Portadown returned to a semblance of normality as the Orangemen dispersed to prepare for last night's 11 July bonfire celebrations.
At Orange Hall, crates of beer and bottles of whisky were carried in. But one lodge member said they would be drinking none that afternoon. He said: "This is not a time for celebration, we do not want to rub their noses in it." A colleague added: "If Sir Hugh Annesley had let us do this on Sunday there would have been none of this hassle."
Back at the Church of Ascension, the scene of the stand-off at Drumcree, it was hard to believe that this church had been a flashpoint for Ulster's future. With the barbed wire and barricades gone, the route outside the graveyard looked like any other quiet country lane.
"It's just a church again," said one Orangeman as he took off his sash.