The Republic of Ireland Act 1948 came into force, describing Ireland as a republic and ending its membership in the Commonwealth of Nations.

The Republic of Ireland Act 1948 is an Act of the Oireachtas which declares that the description of Ireland is the Republic of Ireland, and vests in the president of Ireland the power to exercise the executive authority of the state in its external relations, on the advice of the Government of Ireland. The Act was signed into law on 21 December 1948 and came into force on 18 April 1949, Easter Monday, the 33rd anniversary of the beginning of the Easter Rising.

Ireland, also known as the Republic of Ireland, is a country in Northwestern Europe. It consists of 26 of the 32 counties of the island of Ireland, with a population of about 5.4 million. Its capital and largest city is Dublin, on the eastern side of the island, with a population of over 1.5 million. The sovereign state shares its only land border with Northern Ireland, which is part of the United Kingdom. It is otherwise surrounded by the Atlantic Ocean, with the Celtic Sea to the south, St George's Channel to the south-east and the Irish Sea to the east. It is a unitary, parliamentary republic. The legislature, the Oireachtas, consists of a lower house, Dáil Éireann; an upper house, Seanad Éireann; and an elected president who serves as the largely ceremonial head of state, but with some important powers and duties. The head of government is the Taoiseach, elected by the Dáil and appointed by the president, who appoints other government ministers.

The Commonwealth of Nations, often referred to as the British Commonwealth or simply the Commonwealth, is an international association of 56 member states, the vast majority of which are former territories of the British Empire from which it developed. They are connected through their use of the English language and cultural and historical ties. The chief institutions of the association are the Commonwealth Secretariat, which focuses on intergovernmental relations, and the Commonwealth Foundation, which focuses on non-governmental relations between member nations. Numerous organisations are associated with and operate within the Commonwealth.