6 December 1921 : Irish Free State declared

The Irish Free State, comprising four-fifths of Ireland, is declared, ending a five-year Irish struggle for independence from Britain. Like other autonomous nations of the former British Empire, Ireland was to remain part of the British Commonwealth, symbolically subject to the king. A constitution adopted by the people in 1937 declared Ireland to be a sovereign, independent, democratic state, and the Irish Free State was renamed Éire. The Republic of Éire remained neutral during the Second World War, and in 1949 the Republic of Ireland Act severed the last remaining link with the Commonwealth. Conflicts persisted over Northern Ireland, however, and the Irish Republican Army, outlawed in the south, went underground to try to regain the six northern counties still ruled by Britain