29 December 1937: The new Irish Constitution came into effect on this day. The titles "Executive Council" and "President of the Executive Council" (a Legacy of the Treaty of 1921 with Britain) were changed to read "Government" and "Taoiseach" respectively and the office of President came into existence.
The new Constitution had been approved in a Referendum this year and it marked the culmination of Eamon De Valera’s attempts to undo the Anglo-Irish Treaty of 1921, which he had opposed from day one. De Valera became the first Taoiseach and Douglas Hyde the first President of Ireland or Eire as the Free State now wished to be known. The only residue of the Treaty now left was the link to the Crown through the State’s continued and reluctant membership of the British Commonwealth – but that particular bugbear was to fall (ironically enough) to a leader of Fine Gael to accomplish.