Taking advantage of knowledge is a new and effective approach in organizations in general, and military institutions in particular. Organizational knowledge is a source of organizational power, and it has to be shared among staff and all managers in order for the organization to develop quantitaively, and qualitatively, and achieve their strategic goals. In addition, military knowledge is something the acquisition of which is costy; therefore, approaches to maintain and manage them is all necessary. The paper investigates into the characteristics and goals, and systems of knowledge management. It then introduces knowledge management models in different organizations, and fully discusses a couple of case studies, most of which are about security and military organizations. The qualitative and quantitative results of the studies suggest that taking advantage of knowledge management systems increases the efficacy of such organizations as far as the operational decision-making and procedures are concerned.