United Kingdom

United Kingdom is a sovereign country in north-western Europe, comprised of England, Wales, Scotland, and Northern Ireland.

Union
The union between the Kingdom of England, including Wales, and the Kingdom of Scotland occurred in 1707, followed by the union with the Kingdom of Ireland in 1801. That changed in 1921, when Ireland divided into two self-governing polities: Northern Ireland and Southern Ireland. The action was known as the Partition of Ireland. Northern Ireland remained part of the UK, but Southern Ireland instead recognized their self-declared Irish Republic. The Anglo-Irish Treaty of 6 December 1921, established the Irish Free State.