The acronym MILPAS originally stood for Milicias Populares Anti-Somocistas, fighting alongside the Sandinista National Liberation Front against the regime of Anastasio Somoza Debayle. However, after his overthrow, some disaffected MILPAS veterans revived it as the Milicias Populares Anti-Sandinistas, one of the earliest rebel groups that would form the contra movement.
The earliest contras inside Nicaragua were the MILPAS (Milicias Populares Anti-Sandinistas), peasant militias led by disillusioned Sandinistas. Founded by Pedro Joaquín González, whose nom de guerre was "Dimas", the Contra Milpistas were also known as chilotes (green corn). Even after his death, other MILPAS bands sprouted during 1980-1981. The Milpistas were composed largely of the campesino highlanders and rural workers who would later form the rank and file of the rebellion.
The MILPAS assimilated into the Nicaraguan Democratic Force (FDN). By 1985, most of the FDN's regional commands were headed by MILPAS veterans. By late 1987, the ranks of ex-MILPAS regional commanders included: