When did Ireland and Northern Ireland separate?
Partition of Ireland
The partition of Ireland (Irish: críochdheighilt na hÉireann) 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.
Northern Ireland national football team
In 1920, Ireland was partitioned into Northern Ireland and Southern Ireland. In 1922, Southern Ireland gained independence as the Irish Free State, later to become a republic under the name of Ireland. Amid these political upheavals, a rival football association, the Football Association of Ireland, emerged in Dublin in 1921 and organised a separate league and international team. In 1923, at a time when the home nations had withdrawn from FIFA, the FAI was recognised by FIFA as the governing body of the Irish Free State on the condition that it changed its name to the Football Association of the Irish Free State. The Irish FA continued to organise its national team on an all-Ireland basis.