The exact chronology of the repression occurring before the Operation Condor 's beginning in March 1976 is still debated , but some sectors claim the long political conflict started in 1969 as individual cases of state-sponsored terrorism against Peronism and the left can be traced back to the bombing of Plaza de Mayo and '' Revolución Libertadora '' in 1955 . The Trelew massacre of 1972 , the actions of the Argentine Anticommunist Alliance since 1973 and Isabel Martínez de Perón 's " annihilation decrees " against left-wing guerrillas during '' Operativo Independencia '' ( Operation Independence ) in 1975 have also been suggested as dates for the beginning of the Dirty War
Trelew massacre
Trelew massacre
Dirty War