RUC officers with batons drawn charged a crowd of about 300 loyalists at the upper Ormeau Road in Belfast late last night, dispersing the rioters after 16 hours of confrontation.
During the evening, rioters had used petrol bombs and stones to attack the police, who replied with plastic bullet rounds.
The RUC charge just before 11 p.m. dispersed the main loyalist crowd down side streets. The road was re-opened to traffic but a heavy RUC presence was maintained while small groups of loyalists remained in the area.
The worst loyalist violence in Northern Ireland since last year followed a day long stand off as the RUC prevented an Apprentice Boys' parade marching through the mainly Catholic lower Ormeau Road area.
There were several arrests. and a number of civilians and police officers were treated in hospital for head injuries and cuts.
Tension remained high throughout the city as loyalist fury mounted against the police, and there were fears that the vicious scenes at this first loyalist parade of the marching season could set a dangerous tone for forthcoming contentious parades.
At one stage yesterday evening a crowd of about 600 filled the Ormeau Road, with several Orange bands marching up and down as drunken youths made sporadic attacks on the police.
The numbers were swollen by groups returning from the main Apprentice Boys demonstration in Portadown, Co Armagh.
The trouble developed apparently spontaneously after an impasse on the Ormeau Bridge between the police and a group of Ballynafeigh Apprentice Boys from the upper Ormeau Road who were notified last week that they would not be allowed to pass down the lower Ormeau Road.
The Ballynafeigh Walkers Club of the Apprentice Boys, who had been directed to change their route, paraded to a barricade of RUC Land Rovers on the bridge at 8 a.m. and began their protest.
While most of the Belfast Apprentice Boys groups travelled to the Portadown rally, several bands remained in the city to join the upper Ormeau group in the stand off at the barricade.
There were minor incidents at the bridge throughout the day, but the serious trouble began only after groups returned from Portadown at about 5 p.m. and youths began to launch a barrage of bottles and glasses at police.
The RUC riot squad was called up to the front of the police lines and drove the attackers back up the Ormeau Road, where vicious running battles continued for several hours in the side streets. Up to a dozen petrol bombs were thrown and police fired a number of plastic bullet rounds.
The rioters were mostly youths and were unmasked. Police sources said video film of the confrontations would be carefully examined with a view to prosecutions.
The RUC Deputy Chief Constable, Mr Ronnie Flanagan, blamed "outsiders" for the escalation of the situation and said his men had been forced to advance after a most vicious attack" on them.
During the afternoon, the DUP leader, the Rev Ian Paisley, arrived at the scene and spoke to senior RUC officers. Community activists from the upper Ormeau area also tried unsuccessfully to mediate.
According to reports, some elements of the Apprentice Boys had wished to provoke a watershed confrontation similar to last year's "Siege of Drumcree" over the rerouting issue.
However, the organisation's leadership had sought to calm the situation and had called for a peaceful protest. The club at the centre of the contentious march claimed that its members had been walking the lower Ormeau route for 90 years and had no intention of giving offence to the Catholic community.
The Ormeau Road flash point was the focus of repeated confrontations during last year's marching season.
Yesterday the lower Ormeau enclave was quiet, with most residents remaining indoors and away from the disturbances.
However, the Lower Ormeau Concerned Community (LOCC), which has led the campaign to have Orange marches rerouted, last night called on the RUC to ban all future loyalist parades along the lower Ormeau Road until such times as the loyalist organisations seek and receive the consent of the local residents to such parades."
The Northern Ireland Secretary Sir Patrick Mayhew, said. "The disgraceful attacks on the police are the work of people intent on violent confrontation and disorder... I utterly condemn them as will everyone in Northern Ireland who believe in peaceful and democratic methods. I warmly support the RUC in their efforts to restore order and to maintain the peace."