Irish Political History series 
The political relationship between Britain and Ireland dates to the twelfth century, and reached its height in the Act of Union 1800, which created the United Kingdom of Great Britain and Ireland. In 1922, the southernmost 26 counties of Ireland gained independence from the UK as the Irish Free State (later a republic under the name "Ireland").[1] The remaining 6 counties then constituted the territory of Northern Ireland has remained part of the United Kingdom of Great Britain and Northern Ireland. Unionism and Ulster Unionism, as it is known today, is overwhelmingly concerned with the relationship between Northern Ireland and Great Britain with Unionism today being for all intents and purposes non evident within the rest of Ireland.
Unionism and its opposing ideology, Irish nationalism, are associated with particular ethnic and religious communities the former with Protestants of English or Scottish origin (many of whom migrated to Ireland in the Plantation of Ulster), and the latter with Catholics indigenous to the island. However, these generalisations must be nuanced, since a significant number of individuals do not fit neatly into such sets of categories (there exist both Protestant nationalists and Catholic unionists[2]), and the distinction between a "pure" native Catholic Irish population and "pure" Protestant British colonists is not consistent with the centuries-old history of cross-community intermarriage, cultural assimilation and religious conversion.
The Calvert family and Jacobite Peerage were the last of the old English Catholic aristocracy in Ireland, although with some newer Scottish influences, from the Stuart succession. This was the previous convention, before ties with England absolutely meant Protestantism. It was with the Scottish factor, that the situation changed definitively for the Protestant connection, between Scottish and English people in Ireland, that usually defined them as different from the Irish. By this time, English Catholics were reckoned to be "native Irish" and many of them were just as opposed to Protestant rule as the "Gaelic Irish".
