Sun Tzu
At that time the rules for warfare were based on chivalry. War was the sport of rich noblemen. Sun Tzu refused to see war as a sport. He used Taoist principles and applied them to warfare. In doing so, he changed the rules of war. Unlike generals who enjoyed long campaigns, he understood that war is serious. Sun Tzu believed that once a war started, the goal was to defeat the enemy. Sun Tzu was unconventional in that he did not follow the prevailing wisdom of his time. Other generals were simply unprepared for Sun Tzu's tactics.