The island of Ireland comprises the Republic of Ireland, which is a sovereign country, and Northern Ireland, which is part of the United Kingdom.
The Republic of Ireland endured a hard-fought birth. Ruled from Great Britain since the 13th century, its citizens, many of them suppressed Catholics, struggled to remove themselves from British domination for the next several hundred years.
Ireland’s situation changed dramatically at the beginning of the 20th century. In 1919 an Irish republic was proclaimed by Sinn Féin, an Irish nationalist party. Facing civil war in Ireland, Britain partitioned the island in 1920, with separate parliaments in the predominantly Protestant northeast and predominantly Catholic south and northwest. However, the republicans opposed the formula, and in 1922 the Irish Free State was formed. Almost immediately, the northeast—Northern Ireland—withdrew and accepted self-governance within the United Kingdom.
Dublin was set as the capital of the Irish Free State, and in 1937 a new constitution renamed the nation Éire, or Ireland. In 1949 it became a republic and left the British Commonwealth.
The Protestant majority and Catholic minority in Northern Ireland were in conflict almost from the beginning. In 1969 growing violence between the groups led to the installation of the British Army to maintain the peace, and three years later terrorist attacks in Ireland and Great Britain led to the direct rule of Northern Ireland by the U.K. parliament. In 1985 an Anglo-Irish treaty gave the Republic of Ireland a consulting role in the governing of Northern Ireland. In 1993 the Republic of Ireland and the United Kingdom agreed on a framework for resolving problems and bringing lasting peace to the 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 Great Britain announced plans to leave the European Union following a close 2016 referendum, the impact of the initiative on Northern Ireland became a major issue of debate.