Animosity between the Irish and the English has a long history, dating back to the English Reformation in 1536. England broke with the Catholic church while the Irish remained Catholic, and later English monarchs attempted to convert Ireland by force. Political conflicts between the two countries further inflamed the populace.
Henry VIII broke with the Catholic church in 1536 over the Pope's refusal to grant him a divorce from his wife Catherine of Aragon. Subsequent rulers expanded the rift between the Church of England and Catholicism, and religious persecution of Catholics became a common occurrence. The Reformation also coincided with a reconquest of Ireland, and the Protestant monarchs demanded the Irish convert or be denied power in the new government.
English control of Ireland remained a sore topic for several centuries, and in the early 1900s, militant separatists fought to free Ireland from the United Kingdom. In the end, a treaty was signed that granted independence to most of Ireland, while leaving the northernmost counties under U.K. control. Nationalist groups began to agitate once more for a completely autonomous Ireland in the 1960s, leading to renewed violence between Protestants and Catholics. While the Good Friday Agreement of 1998 restored some of Ireland's autonomy and went a long way toward quelling the violence, there are many who are not going to be satisfied until the entire island of Ireland is its own nation once more.