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.
Flag of Ireland
In 1921, Ireland was partitioned, with the unionist-dominated north-east becoming Northern Ireland, while later, in 1922, the remainder of Ireland left the United Kingdom of Great Britain and Ireland to form the Irish Free State. Northern Ireland continued to use the UK's Union Flag and created its Ulster Banner derivation of the flag of Ulster with a crown on top of a six-pointed star. Furthermore, for many years the tricolour was effectively banned in Northern Ireland under the Flags and Emblems (Display) Act (Northern Ireland) 1954 which empowered the police to remove any flag that could cause a breach of the peace but specified, rather controversially, that a Union Flag could never have such an effect. In 1964, the enforcement of this law by the Royal Ulster Constabulary at the behest of Ian Paisley, involving the removal of a single tricolour from the offices of Sinn Féin in Belfast, led to two days of rioting. The tricolour was immediately replaced, highlighting the difficulty of enforcing the law.