A guerrilla from the Ejército Revolucionario del Pueblo, ERP, prepares a recoilless rifle weapon during a firefight with government security forces in Santa Rosa de Lima, eastern El Salvador, May 1, 1983. The ERP were considered the most militarily powerful of the guerrilla factions that constituted the coalition Frente Farabundo Martí para la Liberación Nacional, Farabundo Martí National Liberation Front, FMLN.