The Derry Citizens' Defense Association (DCDA) was an organisation set up in Derry in July 1969 in response to a threat to nationalist residents from the Royal Ulster Constabulary (RUC) and civilian unionists, in connection with the annual parade of the Apprentice Boys of Derry on 12 August.
[1] This followed clashes with the RUC in January and April 1969, which resulted in widespread violence.
The DCDA played a prominent role in co-ordinating the area's residents in the Battle of the Bogside, and was the effective government of the self-declared Free Derry from August to October 1969.
Its leaders included Seán Keenan, Paddy Doherty and Johnnie White.
Keenan and White were well-known republicans.