War is distinguished from other instruments of policy by its use of organized violence. The use of violence injects elements of emotion and irrationality into war, and this can undermine reason on both sides and impede the pursuit of a purely rational course of action. War is the Province of Uncertainty. Man wages war, and human frailties and irrationality make the course and outcome of war uncertain and unpredictable. War is of the People.
Groups of people wage war and affect the conduct of war.
Group passions, cohesion and determination also affect the conduct of war. Leadership is Crucial in War. Man is the central element in war, and leadership is the critical factor in shaping human effort. Leadership inspires and persuades men and women to help commanders achieve their objectives in spite of adversity and danger. Leadership is both an exercise of character and an application of management and professional skills.