Belfast , Northern Ireland ( CNN ) -- Thousands of people are taking part Saturday in a march through the Northern Ireland city of Belfast that many fear could inflame tensions between Catholics and Protestants . Over the course of the day , up to 30,000 people were expected to join the Ulster Covenant parade , held to mark the 100th anniversary of the signing of a pro-union document which helped shape Northern Ireland 's history . The parade left from Belfast City Hall Saturday morning , headed for the grounds of Stormont , beside the Parliament Buildings . Concerns over potential disorder along the route center have focused on an area near St. Patrick 's Church , where violence flared up between Catholics and Protestants earlier this month . The parade passed near the flashpoint Roman Catholic church , near the city center , without incident Saturday morning but must still return along that route in the evening . Hundreds of police officers are stationed along the route in that area , with many more elsewhere in the city , as the Northern Ireland police service braces for possible trouble . About 2,000 people took part in the morning parade feeding into the main demonstration , in which tens of thousands are expected to take part . The parade , a special event for the Ulster Covenant centenary , is expected to be one of the biggest held in years . Hundreds of parades take place across Northern Ireland each year , the majority involving the Protestant Orange Order and associated organizations , although pro-Irish nationalists also have marches . The Northern Ireland Parades Commission rules on which marches are allowed to take place and which are banned , in an effort to keep friction to a minimum . Most parades pass off peacefully , but when members of one community march near or through neighborhoods dominated by another , violence sometimes occurs . The rioting in Belfast earlier this month , which left dozens of police officers injured , was some of the worst seen by the city in years . Tensions have been high all summer , and behind-the-scenes talks over Saturday 's highly symbolic parade did not succeed in brokering a compromise between the Catholic and Protestant communities over the staging of the event . The Ulster Covenant was a document signed in 1912 by nearly half a million people in opposition to steps by the government in Westminster to introduce `` Home Rule , '' or self-government , in Ireland within the United Kingdom of Great Britain and Ireland . The majority of the island gained independence in 1921 , following two years of conflict . But six of the nine counties of the province of Ulster chose to stay in the United Kingdom , eventually becoming the country of Northern Ireland . In the late 1960s , the conflict between mainly Protestant unionists , who want Northern Ireland to remain part of the United Kingdom , and largely Roman Catholic nationalists , who want it to be reunited with the rest of Ireland , exploded into a political and sectarian war , known as the Troubles . The three decades of ensuing violence between the Irish Republican Army and loyalists claimed the lives of more than 3,000 people , most of them north of the border . While the Good Friday Agreement of 1998 effectively ended the conflict , suspicions between Catholics and Protestants remain . Under the terms of the landmark accord , terrorist groups on both sides dumped their weapons , and Sinn Fein , the political affiliate of the IRA , now work with pro-British politicians in Northern Ireland 's power-sharing government . Journalist Peter Taggart and CNN 's Laura Smith-Spark contributed to this report .
Thousands of police are deployed in Belfast to prevent possible outbreaks of violence . The march marks the centenary of the signing of the pro - union Ulster Covenant . Up to 30,000 people are expected to take part in the march . tensions have been high this summer between Catholics and Protestants in the city .