The Northern Ireland riots of August 1969 marked the beginning of the Troubles. In Belfast, Catholic Irish nationalists clashed with Protestant Ulster loyalists and the mainly-Protestant Royal Ulster Constabulary (RUC), Northern Ireland’s police force. Hundreds of Catholic homes and businesses were burnt out and more than 1,000 families, mostly Catholics, were forced to flee. The rioting ended with Operation Banner, the deployment of British troops. In December 1969, the IRA split into the 'Official' IRA and 'Provisional' IRA, with the 'Provisionals' promising to defend Catholic areas.