January 9th, 1922
Arthur Griffith was elected as the first head of government, then known as “President of Dáil Éireann,” which is now considered an equivalent position to the Taoiseach.
This took place in 1922, after Eamon de Valera steps down and following the establishment of the Irish Free State. Arthur Griffith served as President of Dáil Éireann from January 1922 until his untimely death later that year.
He played a pivotal role in the early government of the Irish Free State and in the formation of the new state. Thank you for the clarification.