Nationalist protesters clashed with police last night as Orangemen completed their homeward journeys along the Crumlin Road, close to the nationalist Ardoyne in north Belfast, and along the Springfield Road at Whiterock in the west of the city.
Most other parts of Northern Ireland emerged relatively unscathed after yesterday's Orange Order Twelfth of July parades at 18 venues throughout the North.
An estimated 60,000 Orangemen, parading behind 800 bands, participated in yesterday's commemoration of the Battle of the Boyne in 1690. An additional Independent Orange Order parade was held at Ballycastle, Co Antrim.
As expected, the main flashpoints were at Ardoyne and along the Springfield Road. Police fired at least 20 plastic bullets as they were attacked by nationalists throwing petrol-bombs, bricks and fireworks on the Springfield Road.
A crowd of about 500 nationalists gathered at the Ardoyne shops to protest as Orangemen paraded home at 8 p.m. Stones, bottles and fireworks were thrown over police lines at the parading Orangemen.
Earlier, police said that they had uncovered republican caches of petrol, paint and acid bombs, as well as a stockpile of iron bars, spiked missiles and bottles on the roofs of shops in the Ardoyne.
According to police, republicans had planned to throw the missiles down on police and soldiers and on Orangemen making their return yesterday evening along the Crumlin Road.
The uncovering of the missiles followed a warning from Assistant Chief Constable Alan McQuillan on Thursday night that republicans were planning to spark a major riot at the shops similar to the vicious clashes in the Ardoyne a year ago.
The Sinn Féin MLA Mr Gerry Kelly said that Mr McQuillan was engaging in "black propaganda" against republicans and the people of Ardoyne.
Outside Belfast there was little trouble, although a crowd of about 200 nationalists attacked police in Ballymena with bricks, stones and bottles as an Orange Order parade was passing by the Dunclug estate.
The Orange Order demonstration at Dundrum in Co Down had to be relocated after a bomb alert close to the field where the Orangemen had been due to gather.
The thrust of many of the speeches from Orange leaders was in opposition to the Belfast Agreement and in demanding that the Sinn Féin ministers, Mr Martin McGuinness and Ms Bairbre de Brún, be expelled from the Executive.
Ulster Unionist MP Mr Jeffrey Donaldson, reflecting a general theme, told Orangemen in Lisburn that the "day of reckoning" for the political process had arrived. He said that there would have to be a renegotiation of the agreement, adding: "Nothing short of the exclusion of Sinn Féin/IRA from ministerial office will do."
The tension in Belfast was exacerbated by the death on Thursday night of William Morgan, a 27-year-old married father of one child, whose wife is pregnant. He was the victim of a hit-and-run attack at North Queen Street in north Belfast last Saturday.
Mr Morgan's family appealed for no retaliation, saying that he had been "in the wrong place at the wrong time and had no connection with any organisation". The appeal may have fallen on deaf ears, however, as a 16-year-old Catholic was stabbed in the neck and back at Glantane Drive, off the Antrim Road in north Belfast, late on Thursday night. The man is in a critical condition in hospital.
The UVF and UDA staged separate displays of strength near Eleventh Night bonfires in the early hours of yesterday. UVF and UDA paramilitaries fired off several shots to cheering crowds on the Shankill and in north Belfast.