United Kingdom has multiple dates related to independence.
» 927 => minor English kingdoms united
» 3 March 1284 => enactment of the Statute of Rhuddlan uniting England and Wales
» 1536 => Act of Union formally incorporates England and Wales
» 1 May 1707 => Acts of Union formally unite England and Scotland as Great Britain
» 1 January 1801 => Acts of Union formally unite Great Britain and Ireland as the United Kingdom of Great Britain and Ireland
» 6 December 1921 => Anglo-Irish Treaty formalizes partition of Ireland; six counties remain part of the United Kingdom and Northern Ireland
» 12 April 1927 => Royal and Parliamentary Titles Act establishes current name of the United Kingdom of Great Britain and Northern Ireland