BELFAST, Northern Ireland (AP) _ Police armored cars barricaded Roman Catholics within their neighborhood Wednesday as Protestant marchers commemorated their side's traditional supremacy in Northern Ireland.

Sporadic violence marred the province's biggest and most divisive holiday, the Twelfth of July, when more than 80,000 Orange Order members and ``kick the pope'' bands celebrate Protestantism and the British crown.

Protesters had hoped to bar one parade of about 300 Orangemen from entering Lower Ormeau, an isolated Catholic neighborhood that was a favorite killing zone for Protestant extremists before their cease-fire last October.

But hundreds of riot police stormed in at daybreak, barred television cameras, shoved pedestrians onto the side streets and blocked each street with armored cars.

It was a blunt but efficient way to prevent a showdown at a time when Northern Ireland's peace process is already under strain.

Efforts to strike a peace settlement since the Irish Republican Army ceased fire 10 months ago have been effectively shelved by the Orange marching season. Protestant ``unionist'' leaders are deeply suspicious of Britain's negotiations with the IRA-supporting Sinn Fein party and demand the IRA's disarmament _ an unlikely prospect _ before they get involved.

About 20,000 Orangemen from all over Belfast marched from downtown to the southern outskirts, where in a broad green field they listened to speeches from senior members, many of whom also lead the Ulster Unionists, the main pro-British party here.

Most Protestants want Northern Ireland to remain part of the United Kingdom, while Catholics want to become part of the Irish Republic.

Befitting a fraternal order consumed by the days when Protestants truly dominated Northern Ireland life, the Orangemen wore dark suits and 1880s-fashion bowler hats, marching in step to fife and drum.

They carried elaborate banners picturing key events and beliefs.

``Trust in God and keep your powder dry,'' advised one honoring Oliver Cromwell, the English rebel whom most Irish revile for slaying tens of thousands in 1649.

The Stranmillis Temperance Volunteers, an Orange lodge committed to shunning alcohol, marched beneath the image of a woman clinging to a stone cross. Its motto: ``If God be for us, who can be against us?''

Some Catholics threw bottles and rocks blindly over police lines as the parade passed by but hit no one. More serious scuffles broke out as the Orangemen left and locals formed up for a counter-march.

About 400 people pushed their way onto the road before riot police formed a solid line in front of them. The protesters sat down in the roadway, flanked by rows of armored cars.

``People have been hemmed into their streets and into their homes. They perceive this very clearly as the police taking the side of the loyalist community against them,'' said the Rev. Anthony Curran, the local parish priest.

The crowd chanted ``S-S, R-U-C!'' comparing the Royal Ulster Constabulary, the predominantly Protestant police force, with Hitler's stormtroopers.

Across the river, police heard the same angry chant from a crowd of hard-line Protestant ``loyalist'' men.

They had hoped to accompany the Orangemen and taunt the Lower Ormeau residents, but police barred the way to non-marchers. Police even patrolled the Lagan River to prevent people from swimming across.

Police later fired plastic bullets at youths stoning them from the only Catholic enclave in east Belfast, after Orangemen shouted taunts at the area as they marched by. There were no reported injuries.

The Twelth of July commemorates the victory in 1690 of the Protestant William of Orange over the forces of King James II, a Catholic.