The Irish Free State (Irish: Saorstát Éireann [sˠiːɾˠsˠˈt̪ˠaːt̪ˠ eːɾʲən̪ˠ]; 6 December 1922 – 29 December 1937) was the state established in 1922 as a Dominion of the British Commonwealth of Nations under the Anglo-Irish Treaty signed by British and Irish representatives exactly twelve months beforehand. On the day the Irish Free State was established, it comprised the entire island of Ireland; but, as expected, Northern Ireland immediately exercised its right under the treaty to remove itself from the new state. The Irish Free State effectively replaced both the self-proclaimed Irish Republic (founded 21 January 1919) and the Provisional Government of the Irish Free State. W. T.