Especially after the more effective prosecution, following the Moro Affair in early 1978, many autonomi went underground, reinforcing groups such as the Red Brigades, the Nuclei Armati Proletari (NAP) (a group active mainly in Naples prisons, where many autonomi members had been incarcerated), the "Squadre Proletarie di Combattimento", the "Proletari Armati per il Comunismo" (PAC), "Azione Rivoluzionaria", the "Unità Comuniste Combattenti" and "Prima Linea", spread mainly throughout northern and central Italy. Also over 200 small, localised, armed groups were briefly active before suppression and/or amalgamation with the second generation of the much larger armed organizations, such as Red Brigades or "Prima Linea" (Front Line), between 1978 and 1982, a period in contemporary Italian history known as the "Years of Lead" ("Anni di Piombo").