A monarchical system of government existed in Ireland from ancient times until the early twentieth century, when it transitioned to the Republic of Ireland. Northern Ireland, as part of the United Kingdom, remains under a monarchical system of government. The Gaelic kingdoms of Ireland ended with the Norman invasion of Ireland (1169–1171), when the kingdom became a fief of the Holy See under the Lordship of the King of England. This lasted until the Parliament of Ireland conferred the crown of Ireland upon King Henry VIII of England during the English Reformation. The monarch of England held the crowns of England and Ireland in a personal union. The Union of the Crowns in 1603 expanded the personal union to include Scotland. The personal union between England and Scotland became a politica