The island of Ireland comprises the Republic of Ireland, which is a sovereign state, and Northern Ireland, which is part of the United Kingdom.

The Republic of Ireland was born in agony. Its citizens had been under British rule since the 13th century and struggled to rid themselves of British rule for the next several hundred years.

Ireland’s situation changed dramatically in the early 20th century. In 1919, the Irish nationalist party Sinn Féin proclaimed the Irish Republic. Faced with civil war in Ireland, Britain divided the island in 1920 with separate parliaments in the predominantly Protestant northeast and the predominantly Catholic south and northwest. This formula was opposed by republicans, however, and the Irish Free State was formed in 1922. Almost immediately, the northeast, Northern Ireland, broke away and accepted self-government as part of the United Kingdom.

Dublin was designated the capital of the Irish Free State, and in 1937 a new constitution renamed the nation Eire, or Ireland. In 1949 it became a republic and withdrew from the British Commonwealth.

The Protestant majority and Catholic minority in Northern Ireland were in conflict almost from the beginning. In 1969, increasing violence between the groups led to the creation of the British army to keep the peace, and three years later terrorist attacks in Ireland and Britain led to direct rule of Northern Ireland by the British Parliament. In 1985, the Anglo-Irish Treaty gave the Irish Republic a consultative role in the governance of Northern Ireland. In 1993, the Republic of Ireland and the United Kingdom agreed a framework for resolving problems and securing lasting peace in a troubled region.

The Republic of Ireland and the United Kingdom of Great Britain and Northern Ireland joined the European Community on January 1, 1973, and were integrated into the European Union in 1993.When the United Kingdom announced plans to leave the European Union following a closed referendum in 2016, the initiative’s impact on Northern Ireland became a major topic of debate.