Even business historians who acknowledge that the Pentagon qualifies by some measures as the world’s biggest business enterprise may be forgiven their lack of interest in it, because business-government relations in the defense sector are widely thought of as abnormal, and rather static. In this paper, I argue that the history of the US defense sector over the past half century (or century) has been more dynamic than we have imagined. In this short paper I focus on two related aspects of what I am calling the de-militarization of the US military-industrial complex since the early 1960s. First, I discuss de-militarization in the sense of privatization and commercialization, with an emphasis on the military's shedding of its in-house production capacities. Second, I describe the marked growth in policymakers' tolerance for higher profit margins among contractors (and its connection to privatization). I hope that the paper will encourage more interest among business historians in the record of the defense sector and its relationship to broader developments in business and economic history.