History of the formation of the United Kingdom Kingdom of England (which included Wales and controlled Ireland) and the Kingdom of Scotland. The once independent Principality of Wales fell under the control of English monarchs from the Statute of Rhuddlan in 1284. The Union of Crowns in 1603, the accidental consequence of a royal marriage one hundred years earlier, united the kingdoms in a personal union, though full political union in the form of the Kingdom of Great Britain required a Treaty of Union in 1706 and Acts of Union in 1707 (to ratify the Treaty). The Act of Union 1800 united the Kingdom of Great Britain with
Unionism in Scotland continued until 1746 and the Jacobite defeat at Culloden. With the Acts of Union 1800, Ireland united with Great Britain into what then formed the United Kingdom of Great Britain and Ireland. The history of the Unions is reflected in various stages of the Union Flag, which forms the flag of the United Kingdom. The larger part of Ireland left the United Kingdom in 1922 however Northern Ireland chose to remain within what is now called the United Kingdom of Great Britain and Northern Ireland. The 300th anniversary of the union of Scotland and England was marked in 2007. The