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.
Ireland
Northern Ireland resulted from the division of the United Kingdom by the Government of Ireland Act 1920, and until 1972 was a self-governing jurisdiction within the United Kingdom with its own parliament and prime minister. Northern Ireland, as part of the United Kingdom, was not neutral during the Second World War and Belfast suffered four bombing raids in 1941. Conscription was not extended to Northern Ireland and roughly an equal number volunteered from Northern Ireland as volunteered from the south.