The policing challenge in recent months has not just been about holding the line – but how it is held.
It has not just been a story of officers battered and bruised, but the thinking and pressure that comes with decision-making in those different street battles.
When to use water cannon, when to use dogs, when to fire plastic bullets, and, all the time, trying to think while watching... watching for bricks and bottles, for scaffolding and chunks of metal, for petrol and blast bombs, all of which have been used to attack and pelt the police lines.
So should we be surprised that officers are fatigued, that there are issues with stress, that some, to quote the Police Federation chairman Terry Spence, are experiencing burnout?
The answer is no.
In moments of calm away from the front lines at Woodvale and in the city centre recently, officers spoke a few words about long shifts stretching across long months.
"I just want to go home," one said, meaning that he and his colleagues need a rest; a break from the constant pressures of these street fights.
The danger in this is that someone is going to be killed.
And those who have stirred up the mood and who then stand back and watch the violence need to think about their words. It is not just police officers who are in danger in these situations.
What if one of the protesters or rioters is killed?
What about those going through the courts and to jail?
What about the damage being done to the image of Belfast and the peace process?
In today's world there is not the money to recruit a thousand more police officers.
So 'mutual aid' is the option that has been used – bringing in officers from other UK forces.
The only other possibility is military support, and the Chief Constable does not want to bring soldiers back on to the streets.
Any such move would scream of crisis.
The reality of front line policing is long hours, lack of sleep, eating out of meal boxes, using portable toilets and standing in the way of the bricks, bottles and petrol bombs.
And there is something else about front lines. They are an indication of political and community failure – a statement that almost 20 years after ceasefires this place and process still has much to do.
The police can hold the line – and they are doing it while others dither in the deadlock and danger of flags, parades and the past.