By the mid-1960s the fragile stability of Northern Ireland began to erode. Liberal Unionists began to experience some doubts concerning the legitimacy of Protestant domination. Roman Catholics, who were already reentering politics, were impressed by the achievements of African Americans in the civil rights struggles of that period in the United States, and they saw their own situation as analogous. Catholic civil rights protests in 1968 set the scene for violent confrontations that rekindled sectarian conflict between the two communities, especially in Belfast and Londonderry.
The Irish Republican Army (IRA) was revived with the emergence of the Provisionals, guerrillas who undertook to protect the Catholic segment of the population in the north from official and unofficial assault and whose political agenda called for the summary departure of the British armed forces and the end of Protestant domination. The Protestant response was the formation of its own paramilitary brigades.
British forces entered the province in the early 1970s, nominally to keep the peace. Soon, however, they came to be viewed by many Catholics as unwelcome agents of a foreign power. The constitution and parliament of Northern Ireland were suspended in March 1972 by the government of the Conservative British prime minister Edward Heath, and a cabinet official, the minister for Northern Ireland, became responsible for the province until December 1999. The British army remained a major presence, and elements of martial law permeated civil and judicial processes in an effort to stem un-diminishing violence. The worst year, in terms of deaths, was 1972, when 467 people were killed, 321 of them civilians. The years from 1971 to 1976 represent the most acute period, with an average of 275 deaths per year due to sectarian violence. The figures for the 1980s showed considerable improvement, but 50 to 100 political murders and assassinations still occurred each year. By the mid-1990s, more than 3,100 had been killed as a result of the conflict.
Among the attempts at reconciliation undertaken during the 1980s was the Anglo-Irish Agreement (1985), which, to the dismay of Unionists, marked the first time the Republic of Ireland had been given an official consultative role in the affairs of the province. In the 1990s, talks were held between the province's major constitutional parties (excluding Sinn Féin, the political wing of the Provisional IRA, on the grounds that the IRA, like the Unionist paramilitary groups, continued to engage in terrorist activity). Frameworks for all-party peace talks (most notably the Downing Street Declaration, 1993) were put forward that guaranteed self-determination for the people of Northern Ireland, promised British government recognition of a unified Ireland if a majority of the province's people agreed, and committed the republic to abandon its constitutional claim to Northern Ireland in the event of a political settlement.
In 1994, both the IRA and the Unionist paramilitary groups announced the cessation of violence...
...The IRA declared a ceasefire in September 1994 in response to the Downing Street Declaration of late 1993, in which the British and Irish governments (Britain and Ireland) agreed to begin peace talks that were to include unarmed, nonviolent groups only; Protestant paramilitary groups joined the ceasefire in October. A further step toward stability was taken in February 1995 with the Framework document, which addressed crucial political issues, including Ireland's claims on Ulster and the right of Ulster's people to determine their own future. These concessions, it was thought, would reduce the influence of the terrorists, whose premise that a political solution was impossible now seemed proven untrue.