Battle of Bogside , Londonderry Westminister MP Bernadette Devlin is in tears after riot police had fired tear gas into a crowd behind berricades in the bogside area of this city of violence . Miss Devlin , who won the mid-Derry seat , yesterday protested that a military gas known as CS was being used by Ulster Police . She said it was also used by Americans in Vietnam and issued to Police here by the British Army for use only ' in grave emergency and under strict control '. 14th August 1969