The article argues that, during the last 30 years, the commitment of the Chilean armed forces during the 1960’s to constitutionalism, legalism, and professionalism has been successively undermined, manipulated and restored. During the Allende government (1970-73) it was undermined by the breakdown of political and economic consensus and the increasing politicization of the armed forces. Between 1973 and 1990 the legalism of the military was manipulated by General Pinochet in order to establish and maintain himself in power. Since 1990 there has been a slow return to the earlier professionalism of the military, marked in particular by the 1995 imprisonment of General Contreras in a civilian jail, the removal from the political scene of General Pinochet in 1998 because of his detention in Great Britain, and the “Never Again” speech of General Cheyre in 2003.