When Sun Tzu first wrote "The Art of War", it was not the first book on military tactics. He quotes from "The Book of Military Administration" by Chun Cheng. The quote is limited to the use of signal flags and drums to move soldiers. Chun cheng's book has not survived to the present day so little is known of what else was in it. But books of that time were based on rules of warfare that all sides followed. War was the sport of rich noblemen. The rules were based on chivalry. Sun Tzu refused to see war as a sport. He used Taoist principles and applied them to warfare. In doing this he changed the rules of war. Unlike generals who enjoyed long campaigns, he understood war was serious. Sun Tzu believed that once a war started, the goal was to defeat the enemy. Sun Tzu was unconventional in that he didn't follow the prevailing wisdom of his time. Other generals were simply unprepared for Sun Tzu's tactics. Sun Tzu mastered the art of being unpredictable in warfare.