1Union Until 1800, Britain effectively treated Ireland as a colony, but the Act of Union made the island an integral part of the United Kingdom of Great Britain and Ireland. In the late 19th and early 20th centuries, the Irish nationalist movement calling for independence grew stronger, giving rise to a Unionist movement that wished to maintain Ireland within the Union. 2The religion conflict Ireland still insisted on Catholicism tradition, and became a strong bulwark of the Roman Catholic church. The different religious beliefs made two national hostile to each other. 3Invasion and Colonization Conflict began when the Anglo-Normans invaded Ireland between 1167 and 1171, although their sphere of influence was largely restricted to the east coast. The English colonised Ireland in the 12th century and for almost 800 years oppressed the indigenous people through force, as England having a much larger army and greater military resources. They tried to eradicate the religion, language, culture and Irish people themselves. 4.Partition In 1921 the British government agreed to give 26 Irish counties a measure of independence as the Irish Free State (from 1949 the Republic of Ireland). The six northeastern counties remained within the United Kingdom as Northern Ireland. 5.Conflict in Northern Ireland Violence flared in Northern Ireland in the late 1960s over whether Northern Ireland should remain in the United Kingdom. More than 3,400 people were killed in more than 30 years of conflict. The Good Friday Agreement, signed in 1998, tried to find a way to bring peace to the region.