March 24th , 1603
The Union of the Crowns (Scottish Gaelic: Aonadh nan Crùintean; Scots: Union o the Crouns) was the accession of James VI of Scotland to the throne of the Kingdom of England as James I and the practical unification of some functions (such as overseas diplomacy) of the two separate realms under a single individual on 24 March 1603. It followed the death of James’s cousin, Elizabeth I of England, the last monarch of the Tudor dynasty.