Republic of Ireland–United Kingdom border
Originally intended as an internal boundary within the United Kingdom of Great Britain and Ireland, the border was created in 1921 under the United Kingdom Parliament's Government of Ireland Act 1920. Prior to this, a separatist Irish parliament had been established in Dublin, which did not recognise the Government of Ireland Act, and was actively engaged in the Irish War of Independence. The Act was intended to deliver Home Rule in Ireland, with separate parliaments for Southern Ireland (which included three of the nine counties of Ulster) and Northern Ireland. Six of the thirty-two counties of Ireland were assigned to Northern Ireland, and the rest of Ireland comprising 26 counties to Southern Ireland.
Irish War of Independence
In May 1921, Ireland was partitioned under British law by the Government of Ireland Act, which created Northern Ireland. Both sides agreed to a ceasefire (or 'truce') on 11 July 1921. The post-ceasefire talks led to the signing of the Anglo-Irish Treaty on 6 December 1921. This ended British rule in most of Ireland and, after a ten-month transitional period overseen by a provisional government, the Irish Free State was created as a self-governing Dominion on 6 December 1922. Northern Ireland remained within the United Kingdom. After the ceasefire, violence in Belfast and fighting in border areas of Northern Ireland continued, and the IRA launched a failed Northern offensive in May 1922. In June 1922, disagreement among republicans over the Anglo-Irish Treaty led to the ten-month Irish Civil War. The Irish Free State awarded 62,868 medals for service during the War of Independence, of which 15,224 were issued to IRA fighters of the flying columns.