The Troubles (Irish: Na Trioblóidí) was an ethno-nationalist conflict in Northern Ireland during the late 20th century. Also known internationally as the Northern Ireland conflict, it is sometimes described as an "irregular war" or "low-level war". The conflict began in the late 1960s and is usually deemed to have ended with the Good Friday Agreement of 1998. Although the Troubles primarily took place in Northern Ireland, at times the violence spilled over into parts of the Republic of Ireland, England, and mainland Europe.
The conflict was primarily political and nationalistic, fuelled by historical events. It also had an ethnic or sectarian dimension, although it was not a religious conflict. A key issue was the constitutional status of Northern Ireland. Unionists/loyalists, who were mostly Protestants, wanted Northern Ireland to remain within the United Kingdom. Irish nationalists/republicans, who were mostly Catholics, wanted Northern Ireland to leave the United Kingdom and join a united Ireland.
The conflict began during a campaign to end discrimination against the Catholic/nationalist minority by the Protestant/unionist government and police force. The authorities attempted to suppress this protest campaign and were accused of police brutality; it was also met with violence from loyalists, who alleged it was a republican front. Increasing inter-communal violence, and conflict between nationalist youths and police, eventually led to riots in August 1969 and the deployment of British troops, who constructed 'peace walls' to keep the opposing communities apart. Some Catholics initially welcomed the army as a more neutral force, but it soon came to be seen as hostile and biased. The emergence of armed paramilitary organisations led to the subsequent warfare over the next three decades.
The main participants in the Troubles were republican paramilitaries such as the Provisional Irish Republican Army (IRA) and the Irish National Liberation Army (INLA); loyalist paramilitaries such as the Ulster Volunteer Force (UVF) and Ulster Defence Association (UDA); British state security forces—the British Army and Royal Ulster Constabulary (RUC); and political activists and politicians. The security forces of the Republic played a smaller role. Republican paramilitaries carried out a guerrilla campaign against the British security forces, as well as a bombing campaign against infrastructure, commercial and political targets. Loyalists targeted republicans/nationalists, and attacked the wider Catholic community in what they claimed was retaliation. At times there were bouts of sectarian tit-for-tat violence. The British security forces undertook both a policing and a counter-insurgency role, primarily against republicans. There were some incidents of collusion between British security forces and loyalists. The Troubles also involved numerous riots, mass protests and acts of civil disobedience, and led to segregation and the creation of no-go areas.
More than 3,500 people were killed in the conflict, of whom 52% were civilians, 32% were members of the British security forces, and 16% were members of paramilitary groups. There has been sporadic violence since the Good Friday Agreement was signed, including a campaign by anti-ceasefire republicans.