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 issue in British politics
Home Rule was passed in 1914, but suspended in operation during the First World War. The issue was finally resolved in 1921 by partitioning Ireland into the quasi-autonomous (Catholic-dominated) Irish Free State in the southwestern four-fifths of the island, and (Prebyterian dominated) Northern Ireland in the remaining fifth, which remained part of the United Kingdom. The next round of troubles emerged in the 1960s, when the Catholics living in Northern Ireland could no longer tolerate the discriminatory policies long imposed on them by the (devolved) government of Northern Ireland. The Troubles 30 years of near civil war that at times had significant impact on British politics finally ended with the Good Friday Agreement of 1998, a power-sharing agreement between the parties in Northern Ireland and a international Treaty between Ireland and the United Kingdom, as co-guarantors.