This paper tries to define the term of leadership, focusing on the leadership and management of organizations with a hierarchical organizational structure. More specifically, it focuses on the leadership of the military services. This paper begins with a brief introduction about leadership and its conceptual approach by various researchers. In the same chapter there is a historical review of leadership and a description of past and present leadership styles. The first chapter ends with measuring the outcome of leadership through measurement tools. In the 2nd chapter, the analysis of the leader as a concept is carried out and the main characteristics of successful leaders are described. The next chapter continues with the conceptual approach to the term management, starting with a brief historical review and continuing with the analysis of the main functions of management. Ending with the description of the term administration, the 4th chapter attempts to compare the above concepts, i.e. leadership and management, recording their main differences. In the 5th chapter leadership and management in an environment of hierarchical authority is studied. Firstly, an introduction to military leadership and administration is made in order to highlight the special characteristics of this type of leadership. In addition, special reference is made to the military leader and the special characteristics he is required to possess in order to be able to lead in a military environment. This work ends with a record of the main conclusions drawn from the study of the above chapters.