Updated: April 1999

The first British involvement in Ireland began in 1169, when Anglo-Norman troops arrived at Bannow Bay in County Wexford. During the next half millenium, successive English rulers attempted to colonize the island, pitching battles to increase their holdings – moves that sparked periodic rebellions by the Irish.

As the English gradually expanded their reach over the island by the 16th century, religious persecution of Catholic Irish grew – in particular after the accession of Elizabeth I, a Protestant, to the throne in 1558. Oliver Cromwell's subsequent siege of Ireland in 1649 ended with massacres of Catholics at Drogheda and Wexford and forced the resettlement of thousands, many of whom lost their homes in the struggle. By 1691, with the victory of Protestant English King William III over the Catholic forces of James II, Protestant supremacy in Ireland had become complete.

Catholics in Ireland suffered greatly in the subsequent period of British occupation, enduring laws that prevented them from bearing arms, holding public office and restricting their rights to an education. While many of those rights were eventually restored, the animosity between Catholics and Protestants remained. With the passing of the Act of Union in 1800, a law that joined England and Ireland as one, the island became officially governed by London.

Home Rule
During the next century, several movements sprang up to push for a more independent Ireland. One of them, the so-called "Home Rule" movement founded in the 1870s, pushed for the establishment of a separate Irish parliament to govern domestic affairs. Through the early 20th century, Home Rule became the focus of political debate, drawing bitter opposition from the island's Protestants, who vowed to resist the movement with violence.

The intervention of World War I prevented the enactment of Home Rule, which was passed by the House of Commons for the second time in 1914. Still, the movement for Irish self-rule continued.

Easter Rising and the Partitioning of Ireland
In 1916, Irish nationalists stormed the General Post Office and other key buildings in Dublin during Easter week, proclaiming the formation of an Irish republic. The uprising failed and most of the leaders were eventually executed. However, the action would create a wave of sympathy for the recently formed Sinn Fein (which advocated Irish independence) and its leader Eamon de Valera, who had barely escaped execution for his role in the uprising. The popular support ran over into the 1918 general election: Sinn Fein won 73 seats to 31 for the Unionists and Independent Unionists, who supported governance from London.

The election mandate encouraged further separatist leanings as Sinn Fein boycotted Westminster the next year, declaring the formation of its own "Dail Eireann" or Irish Parliament in Dublin with de Valera as its President. Violence escalated as the Irish Repubican Army, led by Michael Collins, fought Britain in a bloody war for independence – one that ended with the partitioning of the northern and southern parts of the island by the Government of Ireland Act in 1920.

The partitioning would have a lasting impact on the island as the act provided for separate parliaments: one in Belfast serving six counties in the north and the other in Dublin for the remaining 26 counties. Created as a kind of demographic compromise, Northern Ireland proved to be an area that could comfortably hold a majority in favor of union with Britain. In December 1921, Sinn Fein and British officials signed the Anglo-Irish treaty, which created an Irish Free State over the 26 southern counties, and a northern state of six counties allied with Britain.

The partitioning, however, remained anathema to Irish Republicans, who were bent on the objective of securing a united, independent Ireland by force, if necessary. The IRA waged a violent campaign against the treaty in the 1920s, even killing former comrade Michael Collins, a treaty signatory. The IRA, which was declared illegal in the Irish Free State by 1936, continued its underground campaigns into the 1940s and 1950s.

Beginning of 'The Troubles'
Relative calm followed the Ireland Act of 1949, which created the Republic of Ireland in the south. By the 1950s, even Catholics in the North, still securely tethered to Britain, seemed ready to accept equality rather than pushing for securing a more united Ireland, scholars note.

But that changed after Northern Ireland's Catholics organized a large demonstration protesting discrimination in voting rights, housing and unemployment in 1968. A police crackdown followed, sparking months of violence and a reemergence of the Republican movement. The subsequent bloody riots between Protestants and Catholics marked the beginning of "The Troubles," the euphemism for the period of violence that would continue for years in Northern Ireland.

One of the most infamous acts came in 1972, when British paratroopers opened fire on a group of Catholic demonstrators and killed 14 people. Soon after "Bloody Sunday," Britain disbanded the parliament and would impose direct rule on Northern Ireland for the next 26 years.

Sunningdale Agreement
The Sunningdale Agreement of 1974, which provided for a power-sharing arrangement between British and Irish governments, offered some hope for peace. But the coalition government formed as a result of the agreement collapsed after a Protestant strike and disputes over power-sharing issues, and direct rule resumed.

The sectarian strife continued throughout the 1980s, punctuated by high drama, terrorism and moments of possible political compromise. Bringing the IRA fight into the international spotlight was Bobby Sands, an IRA member who died while on a hunger strike in a Belfast prison to protest his status as a common prisoner, rather than a political one. His passing and the death of nine fellow IRA inmates in 1981 sparked more outrage and riots, and brought increased sympathy for the IRA's drive for a united Ireland.

Anglo-Irish Agreement and the Guildford Four
In 1985, the United Kingdom and the Republic of Ireland signed the Anglo-Irish Agreement, which gave the Irish Republic a consultative role on behalf of Catholics in some matters concerning Northern Ireland. While constant warfare threatened to unravel the agreement, the deal proved to be a watershed, establishing the Irish government as a legitimate player in Northern Ireland for the first time.

The decade ended with the dramatic release of four men jailed for the 1975 Guildford pub bombings, after revelations that concluded police had lied and fabricated confessions. By 1989, some 2,700 people had died in the 20 years of fighting – about 1,900 were civilians.

The 'Downing Street Declaration' and IRA Cease-Fire
As IRA and Protestant killings continued into the early 1990s, Britain began launching multi-party talks with the goal of forging a new assembly for Northern Ireland and new relations between the North and the Irish Republic. The talks broke down in 1992, but the next year, leaders of Britain and Ireland would announce the "Downing Street Declaration," a deal which invited Sinn Fein and Democratic loyalist parties to join the talks on the future of Northern Ireland if both groups renounced violence.

The goodwill toward Sinn Fein spilled into 1994 when the United States granted a visa to its long-outlawed leader, Gerry Adams. The IRA responded later that year with a declaration of its own, announcing a "complete cessation of military operations" in August. The announcement opened the way for talks that year between Sinn Fein and British civil servants, the first in 22 years.

Mitchell Principles and Good Friday Agreement
During the next two years, arguments over disarmament, withdrawal of the IRA cease-fire, and a wave of bombings would further threaten to derail Northern Ireland's progress toward peace. In 1996, an international panel headed by former U.S. Senator George Mitchell offered a compromise to end the deadlock, suggesting Britain drop its insistence that the IRA begin disarming before entering negotiations.

Movement on Mitchell's six principles of non-violence for entry into all-party talks progressed into 1997 as the IRA renewed its cease-fire in July. In September, both Sinn Fein and the Ulster Unionists agreed to the Mitchell principles and entered the all-party talks.

Finally, after 21 months of talks, Northern Ireland's political leaders reached a historic Good Friday agreement on a new form of self-rule for the embattled province, giving minority Catholics a greater voice while meeting Protestant demands that the province remain a part of Britain. The plan was approved resoundingly by voters in the North and the Irish Republic in May 1998. Voters cast ballots in June for the new Northern Ireland Assembly. Backers of the Good Friday agreement earned a controlling majority in the governing body.

Progress on the political front, however, did not stop the violence. In August, terrorists detonated a car bomb amid a throng of shoppers in the town square of Omagh, killing 28 people. It was the single worst terrorist incident since the beginning of the Troubles in the late 1960s. A splinter group of the mostly Catholic Irish Republican Army, known as the "Real IRA," claimed responsibility for the attack.

The bombing was a huge setback for many backers of the peace agreement, who had hoped the 30-year-old struggle – which has taken the lives of more than 3,400 people – was coming to an end.

By 1999, Protestant and Catholic negotiators had turned their efforts to another serious menace to the peace accord: a decision on how and when to dispose of paramilitary arms and munitions held by the two sides. Days of intensive negotiations followed in the spring and summer of 1999, but no agreement was reached.

– Tim Ito and Aileen Yoo, washingtonpost.com staff