This paper by Sean Hannah from the Centre for the Army Profession & Ethic (now The Centre for the Army Profession and Leadership), outlines the unique causations and contingencies influencing leadership in military contexts. He defines what constitutes a Profession of Arms (internal context) and the combat operating environment (external context).  He also offers a working definition of leadership in military professions and defines what it takes to be a professional military leader.  

Based on the definitions and facets of the internal and external contexts, Hannah goes on to discuss the unique phenomenon influencing leadership at the individual level of analysis, such as ethos, emotions, cognition and judgment, identity and self-complexity, individual differences, and motivation. It also analyses effects on leader-follower relationships, leader prototypes, unit composition types, group processes and goals, shared leadership, and collective influences on ethical behaviour. The paper also looks at future directions by studying more macro organizational effects of the military context.  

This paper is a ‘long read’ from an experienced author.  It’s recommended that you set aside a significant period of time to read through the document, or split it up in to manageable sections in order to avoid being overwhelmed by the volume and terminology contained in the paper.