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.
Irish Boundary Commission
The Government of Ireland Act 1920 was enacted during the height of the War of Independence and partitioned the island into two separate Home Rule territories of the United Kingdom of Great Britain and Ireland, to be called Northern Ireland and Southern Ireland. In its determination of this border, the Parliament of the United Kingdom heard the arguments of the Irish Unionist Party, but not those of most of the elected representatives of the Irish nationalist population. Sinn Féin refused to recognise any legitimate role of that Parliament in Irish affairs and declined to attend it, leaving only the Irish Parliamentary Party, whose representation at Westminster had been reduced to miniscule size at the 1918 General Election, present at the debates. James Craig's brother told the British House of Commons unambiguously that the six northeastern counties were the largest possible area that unionists could "hold".