History has returned to disrupt the Northern Ireland peace process - and is threatening to destroy it.
After three days of angry confrontation with police, militant Protestants demanding to be allowed to march through Catholic areas have said they have made too many concessions to the province's religious minority and would boycott peace talks until their concerns were met.
David Trimble, leader of the official Ulster Unionists, said his party would pull out of talks in Belfast, Northern Ireland, chaired by former United States Sen. George Mitchell until the situation was resolved.
As police across Northern Ireland used plastic bullets to quell a spate of violence in which cars and buildings were burned, highways were blocked, and members of the two religious communities came to blows, Northern Ireland Secretary Sir Patrick Mayhew called on provincial leaders to reflect on the damage being done to the prospects of peace.
The standoff near the tiny Drumcree church in Portadown, 25 miles south of Belfast, has sparked the worst disturbances in Northern Ireland since the cease-fires called by the Irish Republican Army (IRA) and Unionists paramilitary groups in August and September 1994.
Hundreds of members of the Orange Order, known as Orangemen, held a church service at Drumcree July 7 and then attempted to march along a stretch of Garvaghy Road where the majority of the residents are Catholics. The Orange Order is a 200-year-old Protestant religious organization committed to keeping Northern Ireland part of the United Kingdom.
Police set up a razor-wire barricade and ordered the march to be rerouted. The Orangemen refused, saying they had always been allowed to march through the area. They claimed that in recent years they already had agreed to reroute many marches away from other Catholic areas.
Last July a standoff at Drumcree church was defused when the Orangemen were persuaded to modify their march.
Ian Paisley, head of the hard-line Democratic Unionists, said British Prime Minister John Major had "caved in" to IRA guerrillas opposed to British rule of Northern Ireland. Neither Mr. Trimble nor Mr. Paisley turned up at the peace talks July 9.
The standoff at Drumcree church took place as a key date in the province's historical calendar loomed. No anniversary in Northern Ireland is more potent than July 12. On that day in 1690 the Protestant monarch, William, Prince of Orange, defeated James, his invading Catholic rival to the throne, at the Battle of the Boyne.
Every year, July 12 is the culmination of what anxious police call the "marching season" - a period of several weeks during which the 100,000 members of the Orange Order and their sympathizers stage demonstrations to proclaim what Paisley and others say is their "Britishness."
Catholics hold symbolic marches too, but they are far fewer and less colorful.
Paul Bew, professor of politics at Queen's University in Belfast, says Protestants believe that in the last year "too many concessions have been made to Sinn Fein," the IRA's political wing, and are "determined not to compromise this time," having made "one compromise too many."
David Sharrock, a longtime analyst of Northern Ireland politics, says that many Protestants regard the marches as a way of "expressing their culture and identity," which they believe is threatened. Catholics, Sharrock says, regard the Orangemen's parades as "foisted on them" and intended as a reminder that Protestants are in a dominant majority.
In northern Belfast, Catholic families were forced to leave their homes as Loyalist protesters menaced Catholic neighborhoods. Police moved swiftly to deal with outbreaks, recalling that in 1969 Loyalist attacks on Catholic homes in Belfast helped to trigger what later turned into 25 years of Northern Ireland "troubles."