Both the Provisional and Official IRA stepped up attacks after Bloody Sunday , with the tacit support of the residents . Local feelings changed , however , with the killing of Ranger William Best by the Official IRA . Best was a 19 @-@ year @-@ old local man who was home on leave from the British Army at his parents ' house in the Creggan . He was abducted , interrogated and shot . The following day 500 women marched to the Republican Club offices in protest . Nine days later , on 29 May , the Official IRA declared a ceasefire . The Provisional IRA initially stated that they would not follow suit , but after informal approaches to the British Government they announced a ceasefire from 26 June . Martin McGuinness was the Derry representative in a party of senior Provisionals who travelled to London for talks with William Whitelaw , the Secretary of State for Northern Ireland . The talks were not resumed after the ending of the truce following a violent confrontation in Belfast when troops prevented Catholic families from taking over houses in the Lenadoon estate .