Sectarian in the context of "The Troubles"

Ulster Protestants are an ethnoreligious group in the Irish province of Ulster, where they make up about 43.5% of the population. Most Ulster Protestants are descendants of settlers who arrived from Great Britain in the early 17th century Ulster Plantation. This was the settlement of the Gaelic, Catholic province of Ulster by Scots and English speaking Protestants, mostly from the Scottish Lowlands and Northern England. Many more Scottish Protestant migrants arrived in Ulster in the late 17th century. Those who came from Scotland were mostly Presbyterians, while those from England were mostly Anglicans (see Church of Ireland). There is also a small Methodist community and the Methodist Church in Ireland dates to John Wesley's visit to Ulster in 1752. Although most Ulster Protestants descend from Lowland Scottish people (some of whose descendants consider themselves Ulster Scots), many descend from English, and to a lesser extent, from Irish, Welsh and Huguenots.

Since the 17th century, sectarian and political divisions between Ulster Protestants and Irish Catholics have played a major role in the history of Ulster, and of Ireland as a whole. It has led to bouts of violence and political upheaval, notably in the Irish Confederate Wars, the Cromwellian conquest of Ireland, the Williamite War, the Armagh disturbances, Irish Rebellion of 1798, the Irish revolutionary period, and the Troubles. Today, the vast majority of Ulster Protestants live in Northern Ireland, which was created in 1921 to have an Ulster Protestant majority, and in the east of County Donegal. Politically, most are unionists, who have an Ulster British identity and want Northern Ireland to remain part of the United Kingdom.

Operation Banner was the operational name for the British Armed Forces' operation in Northern Ireland from 1969 to 2007, as part of the Troubles. It was the longest continuous deployment in British military history. The British Army was initially deployed, at the request of the unionist government of Northern Ireland, in response to the August 1969 riots. Its role was to support the Royal Ulster Constabulary (RUC) and to assert the authority of the British government in Northern Ireland. This involved counter-insurgency and supporting the police in carrying out internal security duties such as guarding key points, mounting checkpoints and patrols, carrying out raids and searches, riot control and bomb disposal. More than 300,000 soldiers served in Operation Banner. At the peak of the operation in the 1970s, about 21,000 British troops were deployed, most of them from Great Britain. As part of the operation, a new locally-recruited regiment was also formed: the Ulster Defence Regiment (UDR).

The Provisional Irish Republican Army (IRA) waged a guerrilla campaign against the British military from 1970 to 1997. Catholics welcomed the troops when they first arrived, because they saw the RUC as sectarian, but Catholic hostility to the British military's deployment grew after incidents such as the Falls Curfew (1970), Operation Demetrius (1971) and Bloody Sunday (1972). In their efforts to defeat the IRA, there were incidents of collusion between British soldiers and Ulster loyalist paramilitaries. From the late 1970s the British government adopted a policy of "Ulsterisation", which meant giving a greater role to local forces: the UDR and RUC. After the Good Friday Agreement in 1998, the operation was gradually scaled down, most military facilities were removed and the vast majority of British troops were withdrawn.

The Peep o' Day Boys was an agrarian sectarian Protestant association in 18th-century Ireland. Originally noted as being an agrarian society around 1779–80, from 1785 it became the Protestant component of the sectarian conflict that emerged in County Armagh, their rivals being the Catholic Defenders. After the Battle of the Diamond in 1795, where an offshoot of the Peep o' Day Boys known as the Orange Boys defeated a force of Defenders, the Orange Order was instituted, and whilst repudiating the activities of the Peep o' Day Boys, they quickly superseded them. The Orange Order would blame the Peep o' Day Boys for "the Armagh outrages" that followed the battle.