Ireland's Partition: From Anglo-Irish Treaty to Brexit

The division of Ireland into the United Kingdom and the Republic of Ireland originates from the Anglo-Irish Treaty signed in December 1921, which concluded the Irish War of Independence. This agreement established the Irish Free State with Dominion status, while six northern counties continued to be part of the UK. Prior to this, the Government of Ireland Act (1920) had legislated the partition. The treaty caused a rift in the revolutionary movement, culminating in civil war in 1922, during which Michael Collins lost his life. Over time, the Irish Free State gained autonomy through the Statute of Westminster (1931), Éamon de Valera's 1937 Constitution, and the Republic of Ireland Act (1948), which eliminated constitutional ties. Northern Ireland, remaining in the UK, faced discrimination against Catholics, igniting the Troubles in the late 1960s. The Good Friday Agreement (1998) introduced the consent principle for reunification. Brexit complicated the open border situation, resulting in the Northern Ireland Protocol, which implemented checks in the Irish Sea.