Over the next three months it were violent clashes , with local youths throwing stones at police . Violence came to a head on Saturday , 19 April after a planned march from Burntollet Bridge to the city centre was banned . A protest in the city centre led to clashes with " Paisleyites " — unionists in sympathy with the anti @-@ civil rights stance of Ian Paisley . Police attempting to drive the protesters back into the Bogside were themselves driven back to their barracks . A series of pitched battles followed , and barricades were built , often under the supervision of Bernadette Devlin , newly elected MP for Mid Ulster . Police pursuing rioters broke into a house in William Street and severely beat the occupant , Samuel Devenny , his family and two friends . Devenny was brought to hospital " bleeding profusely from a number of head wounds . " At midnight four hundred RUC men in full riot gear and carrying riot shields occupied the Bogside . Convoys of police vehicles drove through the area with headlights blazing .