The Irish Free State (6 December 1922 – 29 December 1937), also known by its Irish name Saorstát Éireann, was a state established in December 1922 under the Anglo-Irish Treaty of December 1921. The treaty ended the three-year Irish War of Independence between the forces of the Irish Republic—the Irish Republican Army (IRA)—and British Crown forces.
The Free State was established as a dominion of the British Empire. It comprised 26 of the 32 counties of Ireland. Northern Ireland, which was made up of the remaining six counties, exercised its right under the Treaty to opt out of the new state.