Northern Ireland (Ulster)

Long-lasting low-intensity civil conflict 1969-98.
 
Historical background: the 1690 English subduing of Ireland and, on Irish independence in 1920, partition of Ireland, creating a separate Northern Ireland under British rule, favouring Protestant Unionists. This has been mainly a social-political conflict defined and inflamed by religious differences.
 
‘The Troubles’ started in 1969, ending in 1998 with the Good Friday Agreement and the eventual restoration of self-rule in 2007. 3,500 people have been killed, and much social and sectarian bitterness have arisen.  There have been various factions on both sides, political and paramilitary. Murders, atrocities, crime, sectarian marches, heavy-handed British military interventions, pro-Unionist involvement of British secret services, and IRA bombings in England.
 
The political atmosphere has often been dominated by extremism, overriding a quieter moderate majority. This majority gradually gained the upper hand in the 1990s, as social exhaustion and pro-peace, pro-normalisation values grew stronger. Subsidence of violence was helped by late-1990s UK-Irish mediation (Blair and Ahern), the growth of the EU and increasing Irish prosperity. The conflict is now largely resolved, with some outstanding social issues for the longterm, such as criminal activities by ex-paramilitaries, and small renegade paramilitary groups on both sides.
 

Links:

Wikipedia: The Troubles
Flashpoints: Northern Ireland
BBC: A State Apart
Univ of Ulster: Academic Sources on the Conflict
Ulster Conflict Timeline