The Irish Republican Army ( IRA ) began to re @-@ arm and recruit after August 1969 . In December 1969 it split into the Official IRA and the Provisional IRA . Both were supported by the people of the Free Derry area . Meanwhile , relations between the British Army and the nationalist community , which were initially good , deteriorated . In July 1971 there was a surge of recruitment into the IRA after two young men were shot and killed by British troops . The government introduced internment on 9 August 1971 , and in response , barricades went up once more in the Bogside and Creggan . This time , Free Derry was a no @-@ go area , defended by armed members of both the Official and Provisional IRA . From within the area they launched attacks on the British Army , and the Provisionals began a bombing campaign in the city centre . As before , unarmed ' auxiliaries ' manned the barricades , and crime was dealt with by a voluntary body known as the Free Derry Police .