5 October 1968: A Civil Rights march attended by some 2,000 people and organised by local activists and the NICRA was attacked by the RUC in the Waterside district of Derry. Serious rioting then erupted in the wake of the breaking up of the demonstrators. That night and the following day further clashes occurred and some 80 members of the public and 11 RUC men were injured. The pictures subsequently shown on TV throughout Britain and Ireland and further afield awoke large bodies of public opinion to the sectarian nature of the northern State and from that day on the ‘Troubles’ in the North were to be continually front page news.

'The Civil Rights march in Derry on 5 October 1968 was organised to draw attention to a series of grievances over issues related to housing, employment and electoral practices in the city. The driving force behind the idea for the march was a group of left-wing radicals who, through the Derry Housing Action Committee (DHAC) and other organisations, had been taking non-violent direct action to try and improve conditions in the area. The Northern Ireland Civil Rights Association (NICRA) was contacted and following a meeting the NICRA decided to support the proposed march. When the march was publicised Loyalists announced that they were holding an 'annual' parade on the same day, at the same time, and over the same route. The Stormont government then issued a banning order on all marches and parades. When the demonstration went ahead the Royal Ulster Constabulary (RUC) blocked the route of the march and then baton charged the crowd. The scenes were recorded by television cameras and the subsequent news coverage sparked rioting in Derry. Most commentators consider the 5 October 1968 to be the start date of 'the Troubles'.
http://cain.ulst.ac.uk/events/derry/sum.htm