elections the Irish Declaration of Independence was penned and Irish republicans launched a guerrilla campaign against British rule in what became the Irish War of Independence (January 1919 – July 1921). The fighting in Ulster during the Irish War of Independence generally took the form of street battles between Protestants and Roman Catholics in the city of Belfast. Estimates suggest that about 600 civilians died in this communal violence, the majority of them (58%) Roman Catholics (see The Troubles (1920–1922)). The IRA remained relatively quiescent in Ulster, with the exception of the south Armagh area, where Frank Aiken led it. A lot of IRA activity also took place at this time in County Donegal and the City of Derry, where one of the main Republican leaders was Peadar O'Donnell. Hugh O'Doherty, a Sinn Féin politician, was elected mayor of Derry at this time. In the First Dáil, which was elected in late 1918, Prof. Eoin Mac Néill served as the Sinn Féin T.D. for Londonderry City. 1920 to present Partition of Ireland, first mooted in 1912, was introduced with the enactment of the Government of Ireland Act 1920, which gave a form of "Home rule" self-government to two areas, Southern Ireland, with its capital at Dublin, and "Northern Ireland", consisting of six of Ulster's central and eastern counties, both within a continuing United Kingdom of Great Britain and Ireland. Dissatisfaction with this led to the Irish War of Independence, which formally ceased on 11 July 1921. Low-level violence, however, continued in Ulster, causing Michael Collins in the south to order a boycott of Northern products in protest at attacks on the Nationalist community there. The Partition was effectively confirmed by the Anglo-Irish Treaty of 6 December 1921. One of the primary stipulations of the treaty was the transformation of Ireland into a self-governing British dominion called the Irish Free State (which later became the sovereign Republic of Ireland), but with the option of a continuation of the home rule institution of Northern Ireland, still within the United Kingdom, if the Northern Ireland Parliament (already in existence) chose to opt out of the Irish Free State. All parties knew that this was certain to be the choice of the Ulster Unionists who had a majority in the parliament, and immediately on the creation of the Free State they resolved to leave it. Following the Anglo Irish treaty, the exact border between