The Republic of Ireland is predominantly Catholic. Northern Ireland, which is part of the United Kingdom, has a Protestant majority. The Catholic majority in the south, for the most part, strongly favors an independent, united Ireland. The Protestants in the north, for the most part, are pro-British. They are afraid that Irish unification might bring with it Catholic dominance.
The two terrorist armies caught in this religious conflict are the Catholic Irish Republican Army (IRA), which is against British occupation and the Northern Ireland government, and the Protestant Ulster Defense paramilitaries, which are anti-Catholic. Both sides reached a “peace” agreement in May, and yet no terrorist weapons were turned over, and a handful of terrorists were released from prison. Not exactly a recipe for peaceful relations.