From the introduction:
he war master is a new base class, designed for use with the Pathfinder RPG. It is a class designed to lead others in battle, using (mostly) nonmagical talents to grant combat benefits to friends and followers, place enemies at disadvantages, and use the many arts of war in all aspects of his life. A war master is designed to allow both experienced tacticians and players with no sense of strategy to play a cunning commander able to turn the tide of battle with a quick command, clever stratagem, and strong sword-arm used in just the right way at just the right time.
The war master is a warrior, leader, and strategist. As their name might suggest, typical war masters are first and foremost military commanders, able to both slay foes directly and to aid his allies by suggesting various tactics and maneuvers to maximize their gifts and minimize their weaknesses. But the art of war is far more than the ability to kill and lead killers, and war masters must also learn at least some skills of negotiation, espionage, and organization to dominate all aspects of armed conflict. Similarly, the lessons learned in battle can often be applied in less violent venues, allowing war masters to see how to gain advantage in a wide range of situations.