There were at least 3 separate mass actions in Buenos Aires to commemorate the victims of the military coup on 24 March 1976http://www.pagina12web.com.ar/diario/elpais/1-48931.html (in Spanish from Pagina 12, an excellent left-wing daily from Buenos Aires - there are several articles in the dossier).
http://www.yendor.com/vanished/ The disappeared - in English.
24 March also marks a Nazi revenge massacre that touches me personally, the Fosse Ardeatine (Ardeatine Caves) massacre in Rome of over 300 Roman civilians as punishment for a killing of SS by Roman partisan fighters. The victims were antifascists, Jews, and some Romans who were neither.
http://www.zchor.org/italy/caves.htm Fosse Ardeatine massacre (in English)
http://www.romacivica.net/novitch/FosseArdeatine/fosse.htm (in Italian)
The brown thread between these two moments in fascism was one Erich Priebke, responsible for the Roman massacre, who fled to Argentina where he lived for decades in Bariloche, a German settlement in the south where several old Nazis lived and continued to propagandise fascist hate. Several of those old guys were advisers, along with alumni of the School of the Americas, to military dictatorships in Latin America including Argentina and Chile.