Scenes of mob violence were a reminder of how fragile peace can be, writes Gerry Moriarty, Northern Editor.
Riots have a peculiar dynamic. One minute on the Ardoyne Road on Monday evening, neighbours, some distance from where the main body of nationalist protesters were gathered, were leaning over railings amiably chatting to each other.
They appeared not too bothered by, or at least feigned indifference to, the huge security operation confronting them. They'd seen it all before down the years.
The next minute, some of the same neighbours were going haywire, urging on the men and women who - spontaneously, it seemed - rushed from the main protest and started attacking British soldiers at Ardoyne Road and were determined to inflict serious injury and, if possible, worse.
"Go up and bate the bastards to death," one woman, beside herself with rage, exhorted, and there were no shortage of volunteers willing to do just that.
The wonder is that soldiers, police officers or rioters were not killed as a result of the violence. For a couple of minutes up at Ardoyne on Monday, there was a flashback of the terrible mob violence that resulted in the IRA murders of the two British corporals, Derek Wood and David Howes, in west Belfast 16 years ago.
There was a brief period when one or two of the soldiers were in mortal danger of being isolated from their colleagues on the Ardoyne Road. Had that happened, such was the fury of the rioters that yesterday's newspaper headlines would have been much grimmer than they were.
Nationalist anger was still palpable in Ardoyne yesterday. Sinn Féin president, Mr Gerry Adams, along with colleagues such as Mr Gerry Kelly and Mr Alex Maskey, went to a semi-public meeting in Ardoyne (reporters were barred) where they had to take considerable gyp from the audience.
It was important, however, that people could vent their anger in this manner rather than on the streets. Still it can't have been pleasant for the Sinn Féiners to take such grief. This may account for the fact that Mr Adams was once again chastising The Irish Times, and also RTÉ, yesterday.
His beef with us was our reference to "senior Provisional republicans" working to quell the violence. Mr Adams was not denying that figures such as Mr Bobby Storey and Mr Kelly played a positive role in difficult circumstances, but he does not like the term "Provisional".
House style, he advised, should be "senior republicans". However, the Provisional distinction is generally understood and was valid because there were dissident and other republicans in Ardoyne on Monday evening who would dearly have loved to have seen north Belfast erupt in major sectarian violence.
The fact that it didn't was down to the stewarding by people such as Mr Storey and Mr Kelly, who for his trouble in trying to force back the rioters appeared to have been batoned on the wrist by the police or army during the disturbances. Adding insult to his injury, nationalists also jostled Mr Kelly aside when he urged them to desist from their violence.
Mr Kelly, who had his arm in a sling yesterday, might not agree but it was also down - by any objective view - to the restraint of the soldiers and PSNI officers, who, despite being attacked with planks, a pram, sticks, hammers, stones, bottles, bricks and fireworks, only baton-charged when the alternative was the serious injury or possible death of soldiers or police officers.
In the nature of these events, yesterday was a day for recrimination. Nationalists blamed the police and Northern Secretary, Mr Paul Murphy, for allowing the supporters of the Ligoniel Orangemen past the Ardoyne shops. Unionists and Orangemen blamed nationalists for initiating the violence. Everyone blamed the Parades Commission.
The Taoiseach, Mr Ahern, queried why the loyalists were allowed return through Ardoyne when, he said, the commission banned them from this route - a point similarly made by nationalists.
The counter-claim from the PSNI and unionists was that a judicial review on Friday effectively over-ruled part of the commission's determination on the parade by stating the commission could not have jurisdiction over what the supporters of the Orangemen did or did not do.
They also argued that because the supporters were pushed through Ardoyne five minutes after the Orangemen, they could not be perceived as part of the parade.
We are in ambiguous or Jesuitical territory here, but perhaps a more reasonable point was made by the police that, effectively, the army and PSNI were locked in a Catch 22 situation: if the supporters did not get through you could have had loyalists descending on north Belfast for another potential Drumcree, as in the bad days of Drumcree; or, as happened, the barely managed violence of Monday night.
What is unambiguous is neither nationalist troublemakers nor the loyalist hotheads distinguished themselves at Ardoyne. Some of the loyalists were very drunk and acting in a provocatively sectarian manner, although such was the height of the security barriers that nationalists could not see them.
As for the nationalist rioters, whatever about their complaints about being locked into their neighbourhood by the army and police facilitating Orangemen and loyalists, the manner in which they reacted can only be described as a terrifying form of violence that no community would want to indulge or excuse.
Up to around teatime on Monday, it seemed that the North would be in for a blessedly peaceful summer. But by Monday night some of that hope was in tatters. What's worse is that between now and difficult political negotiations in September, two more loyal order marches are scheduled to parade past Ardoyne.
It's going to be a trickier business than expected getting us through the rest of the marching season.