ideologically committed to overthrowing both the Northern Ireland and the Free State governments by force of arms to unify Ireland. The government of Northern Ireland passed the Special Powers Act in 1922, giving sweeping powers to the government and police to intern suspects without trial and to administer corporal punishment such as flogging to re-establish or preserve law and order. The Act continued to be used against nationalists long after the violence of this period had come to an end. In 1920, in local elections held under proportional representation, nationalists had won control over many local governments, including the County Councils of Fermanagh and Tyrone, and the Londonderry Borough Council governing Derry City. In response, in 1922 the new unionist government re-drew the electoral boundaries to give its supporters a majority and abolished proportional representation in favour of first past the post voting. This resulted in unionist control of areas such as Derry City, Fermanagh, and Tyrone where they were actually a minority of voters. The two sides' positions became strictly defined following this period. From a unionist perspective, Northern Ireland's nationalists were inherently disloyal and determined to force unionists into a united Ireland. This threat was seen as justifying preferential treatment of unionists in housing, employment and other fields. The prevalence of larger families and thus the potential for a more rapid population growth among Catholics was seen as a threat. Unionist governments ignored Edward Carson's warning in 1921 that alienating Catholics would make Northern Ireland inherently unstable. After the early 1920s, there were occasional incidents of sectarian unrest in Northern Ireland. These included severe rioting in Belfast in the 1930s and 1950s, and the IRA's brief Northern Campaign in the 1940s and Border Campaign between 1956 and 1962, which did not enjoy broad popular support among nationalists. After the IRA called off its campaign in 1962, Northern Ireland became relatively stable for a few years. Late 1960s There is little agreement on the exact date of the start of the Troubles. Different writers have suggested different dates. These include the formation of the modern Ulster Volunteer Force in 1966, the civil rights march in Derry on 5 October 1968, the beginning of the 'Battle of the Bogside' on 12 August 1969 or the deployment of British troops on 14 August 1969. Civil rights campaign and unionist backlash In March and April 1966, Irish nationalists/republicans held parades throughout Ireland