Following Irish defeat at the Battle of Kinsale, though, the region's Gaelic, Roman Catholic aristocracy fled to continental Europe in 1607 and the region became subject to major programmes of colonialism by Protestant English (mainly Anglican) and Scottish (mainly Presbyterian) settlers.
A clash between the House of Commons and House of Lords over a controversial budget produced the Parliament Act 1911, which enabled the veto of the Lords to be overturned.
A rebellion in 1798 led by the cross-community Belfast-based Society of the United Irishmen and inspired by the French Revolution sought to break the constitutional ties between Ireland and Britain and unite Irish people of all religions.
Following this, in an attempt to quell sectarianism and force the removal of discriminatory laws (and to prevent the spread of French-style republicanism to Ireland), the government of the Kingdom of Great Britain pushed for the two kingdoms to be merged.
The region that is now Northern Ireland was the bedrock of the Irish war of resistance against English programmes of colonialism in the late 16th century.
The English-controlled Kingdom of Ireland had been declared by the English king Henry VIII in 1542, but Irish resistance made English control fragmentary.