The group was founded in 1969, as a breakaway group of the National Front of Catalonia. Jaume Martínez Vendrell, the leader of the military wing of the National Front, became its commander. EPOCA trained its militants in urban warfare techniques, smuggling in weaponry from Switzerland.
The group came to prominence through a number of assassinations, committed by attaching pressure-triggered bombs to the bodies of their victims, demanding ransoms, and when they weren’t received, leaving the bombs to explode, killing their victims in the process. In this way, the group assassinated in 1977 the industrialist and chemical tycoon José María Bultó, and in 1978 the ex-mayor of Barcelona, Joaquín Viola, along with his wife.
By 1979, the group had become inactive in comparison with many other contemporary groups. Following discussions with paramilitaries from Terra Lliure, the groups decided to merge. This led to many of the better-trained EPOCA militants joining Terra Lliure.