A civilian , one of 18 persons , including nine policemen , injured in Londonderry last night , is helped away by comrades after a clash betwen two groups in the city's Carlisle Square . The trouble began when bottles were thrown from a predominantly protestant area towards 200 young civil rights sympathisers who had come from a citizens' action committee meeting . Steel-helmeted police moved into the area and were attacked with bottles and stones . 20th November 1968