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.
Northern Ireland
As a consequence of the worsening security situation, autonomous regional government for Northern Ireland was suspended in 1972. Alongside the violence, there was a political deadlock between the major political parties in Northern Ireland, including those who condemned violence, over the future status of Northern Ireland and the form of government there should be within Northern Ireland. In 1973, Northern Ireland held a referendum to determine if it should remain in the United Kingdom, or be part of a united Ireland. The vote went heavily in favour (98.9%) of maintaining the status quo. Approximately 57.5% of the total electorate voted in support, but only 1% of Catholics voted following a boycott organised by the Social Democratic and Labour Party (SDLP).