Partition of Ireland
The partition of Ireland () divided the island of Ireland into two distinct jurisdictions, Northern Ireland and Southern Ireland. It took place on 3 May 1921 under the Government of Ireland Act 1920. Today the former is still known as Northern Ireland and forms part of the United Kingdom, while the latter is now a sovereign state also named Ireland and sometimes called the Republic of Ireland.
Royal and Parliamentary Titles Act 1927
As a result of the Anglo-Irish Treaty, in 1922 most of Ireland was detached from the United Kingdom of Great Britain and Ireland to become the Irish Free State. However, six north-eastern counties remained united with Great Britain as Northern Ireland.