As with all dominions, provision was made for an Oath of Allegiance. Within dominions, such oaths were taken by parliamentarians personally towards the monarch. The Irish Oath of Allegiance was fundamentally different. It had two elements; the first, an oath to the Free State, as by law established, the second part a promise of fidelity, to His Majesty, King George V, his heirs and successors. That second fidelity element, however, was qualified in two ways. It was to the King in Ireland, not specifically to the British King. Secondly, it was to the King explicitly in his role as part of the Treaty settlement, not in terms of pre-1922 British rule. The Oath itself came from a combination of three sources, and was largely the work of Michael Collins in the Treaty negotiations. It came in part from a draft oath suggested prior to the negotiations by President de Valera. Other sections were taken by Collins directly from the Oath of the Irish Republican Brotherhood, of which he was the secret head. In its structure, it was also partially based on the form and structure used in the Dominion of Canada.
Though controversially moderate by other dominion standards, and notably indirect in its reference to the monarchy (and hence widely criticised by unionists and other dominions), it was criticised by nationalists and republicans for making any reference to the Crown, the claim being that it was a direct oath to the Crown, a fact demonstrably incorrect by an examination of its wording. But in 1922 Ireland and beyond, it was the perception, not the reality, that influenced public debate on the issue. Had its original author, Michael Collins, survived, he might have been able to clarify its actual meaning, but with his assassination in 1922, no major negotiator to the Oath's creation on the Irish side was still alive, available or pro-Treaty. (The leader of the Irish delegation, Arthur Griffith had also died in August 1922). The Oath became a key issue in the resulting Irish Civil War that divided the pro- and anti-treaty sides in 1922–23.
The Irish Free State came into being on December 6, 1922, replacing two co-existing but nominally rival states: the de jure Southern Ireland, which had been created by the Government of Ireland Act 1920 and which from January 1922 had been governed by a Provisional Government under Michael Collins; and the de facto Irish Republic under the President of Dáil Éireann, Arthur Griffith, which had been created by Dáil Éireann in 1919. (In August 1922, both states in effect merged with the deaths of their leaders; both posts came to be held simultaneously by W.T. Cosgrave.)
The Governor-General was formally appointed by the King, but in practice chosen by politicians. Until 1927 he was selected by the British Government, but after that date the Irish Government assumed the right to choose the office-holder. This change arose from the Royal and Parliamentary Titles Act 1927, enacted at Westminster after an agreement reached between the UK and its dominions at an Imperial conference.
The Republic of Ireland Act was an enactment of Oireachtas Éireann passed in 1948, which came into force on April 18, 1949 and which declared that the official description of the Irish state was to be the Republic of Ireland. It officially made the Irish state a republic and marked its exit from the Commonwealth.
