The A to Z of the "Dirty Wars" covers the most recent period of military dictatorship in Argentina (1976-1983), Chile (1973-1990), and Uruguay (1973-1985), when national-security regimes waged war against suspected subversives. The chief targets of these regimes were leftists, especially armed guerrillas and their supporters, though the term "subversive" came to include anyone perceived to be a threat to the status quo. Unlike a conventional war fought against a physical enemy, a "dirty war" (guerra sucia) is fought against an ideology. The difficulty of rooting out such an unconventional...