A number of officers were injured in Belfast last night - with one police woman taken to hospital - after being attacked by masked protestors throwing petrol bombs, bricks, bottles and, in one instance, a blast bomb.
In the most serious incident, police fired baton rounds and deployed water cannons in an effort to control nationalist rioters in the Ardoyne area in the north of the city.
The violent scenes at the flashpoint were all too familiar as crowds targeted officers who were there to escort a planned Orange march past the interface dividing loyalist and republican neighbourhoods.
Police were also attacked by rioters in violent flare ups elsewhere in Belfast and in other areas across Northern Ireland, including Lurgan, Co Armagh and Armagh city.
Last night's disturbances came after three police officers were shot with shotgun pellets during another bout of rioting in Belfast on Sunday night.
While the vast majority of Orange parades on the Twelfth - a traditional Protestant holiday marking the Battle of the Boyne in 1690 - pass without incident, the failure to resolve the competing demands of Orangemen and nationalist residents over the few remaining contentious marches invariably brings disorder to streets each July.
Police Service of Northern Ireland Assistant Chief Constable Alistair Finlay said the challenge was to find a way to resolve the sensitive parades for good.
"This is the only way we can move away from the disorder, tensions and fear that grips Northern Ireland every year," he said.
Sinn Fein and the Democratic Unionists hammered out a new blueprint for parade management as part of the historic Hillisborough Agreement that secured the powersharing institutions in February.
The plan would see the controversial Parades Commission adjudication body replaced with a model more focused on obtaining local settlements to contentious marches.
But the proposals, which are due to come into effect at the start of next year, suffered a blow last week when the Orange Order rejected them.
Mr Finlay said: "We need to see real joined-up strategic political leadership, backed up by everyone in communities making their peaceful voices heard.
"Northern Ireland cannot afford to have violent images beamed across the world every summer - images which are totally unrepresentative of the vast majority of people who have embraced a peaceful and vibrant future."
Heavily armed riot police flanked the Orange lodge members as they made their way past the Ardoyne shops on the Crumlin Road.
They had to fend off a barrage of missiles thrown by nationalists angry that the annual march was allowed to take a route past their area.
Earlier, around 60 demonstrators who blocked the road in a sit-down protest were forcibly removed by officers in body armour.
As the incident unfolded a large crowd of loyalists gathered further up the road in a predominantly unionist neighbourhood to await the Orangemen, who were returning from the main Belfast Twelfth commemoration.
On Sunday night, two policemen and one policewoman were blasted with a shotgun fired by a masked man who emerged from a crowd of nationalists who attacked the police as traditional Protestant 11th Night celebrations took place.
Another 24 officers sustained injuries in that and a further separate riot on Sunday. Police said none of the injuries were life-threatening.