A monarchical system of government existed in Ireland from ancient times until—for what became the Republic of Ireland—the early twentieth century. 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, 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 political union with the enactments of the Acts of Union 1707, which created the Kingdom of Great Britain. The crowns of Great Britain and Ireland remained in personal union until it was ended by the Acts of Union 1800, which united Ireland and Great Britain into the United Kingdom of Great Britain and Ireland from January 1801 until December 1922.