ABSTRACT
Whenever you engage an enemy in battle, the Three Armies absolutely must secure advantageous terrain; only then can the few contend with the many and the weak attain victory over the strong. Sun-tzu said that "knowing that the enemy can be attacked and that our troops can mount an attack, without knowing the advantages of terrain, is only half of victory." This asserts that when one already knows the other, and moreover knows himself, but fails to gain the assistance of advantageous terrain, the victory will not be complete. It is a tactical principle that "the seasons of Heaven are not as good as advantages of Earth."
