The Irish Free State officially came into existence on the 6th December 1922, twelve months after the signing of the Treaty.
Michael Collins and his team had travelled to Britain the previous year to negotiate the terms of the Treaty.
The terms stated that the Free State was a dominion of the British Commonwealth which in no way would be allowed to secede from the Commonwealth and as such the Irish government was required to sign an Oath of Allegiance to the King.
Also, the 26 counties of Southern Ireland were turned over to the Irish delegates while the 6 counties of Northern Ireland were given the right to opt out of the new state if they wished. On December 7th 1922, the Northern Irish Parliament voted to remain in the United Kingdom.
British concessions included the right to name the new state. The honour fell to Michael Collins who chose the “Irish Free State” coming from the Irish “Saorstait”. The Irish Free State also had complete control over its finances and customs and British troops were to evacuate Ireland, with a new Irish army and police force to be established.(British Cavalry evacuating Ireland in 1922)
The treaty was divisive and lead to Civil war in Ireland which ended in 1923. Upon signing the treaty Michael Collins is reported to have said “I may have signed my actual death warrant”. Collins was killed in an ambush in Cork in August 1922.
In 1932 Eamon de Valera became president; one of his first acts was to abolish the Oath of Allegiance. In 1937 a new constitution was adopted declaring Ireland as a new state (Éire) and in 1949 the Republic of Ireland was established.