Whoever is first in the field and awaits the enemy will be fresh for the fight. Whoever is second and has to hasten there will arrive exhausted. From that difference Sun Tzu draws the rule that the clever combatant imposes his will on the enemy and does not allow the enemy's will to be imposed on him. A held-out advantage makes the enemy approach of his own accord. Damage makes it impossible for him to draw near. Rest, a full supply of food, and a quiet camp are all things that can be taken away from him. The march itself stays cheap when it goes through country where the enemy is not, and the appearance is made at the point he must hasten to defend. Attack only what is undefended, and the attack succeeds. Hold only what cannot be attacked, and the defence is safe. The skilful attacker is the one whose opponent does not know what to defend. The skilful defender is the one whose opponent does not know what to attack. Subtlety and secrecy make him invisible and inaudible, and then the enemy's fate is in his hands.
That uncertainty is how a smaller or later force still chooses the fight. If he wishes to fight, he attacks some other place the enemy will be obliged to relieve, and the engagement is forced even from behind a high rampart and a deep ditch. If he does not wish to fight, he throws something odd and unaccountable in the enemy's way, and the enemy will not engage even when the lines of the camp are merely traced on the ground. Discover the enemy's dispositions and remain invisible, and one's own force stays a single body while his must split. A whole then meets separate parts. Hide the place and the time of the coming battle, and he has to prepare at several points, weakening van, rear, left, and right together. Numerical weakness comes from having to prepare against possible attacks. Numerical strength comes from compelling the adversary to make those preparations. The soldiers of Yueh may exceed one's own in number. That surplus advantages them nothing if they do not know where the blow will fall.
Rouse him and he reveals whether he means to act or to lie still. Compare the two armies and the surplus of strength, and the thin place, become visible. The highest disposition is the one that stays concealed, so the subtlest spies and the wisest brains cannot lay plans against it. All men can see the tactics whereby a victory is won. What none can see is the strategy out of which the victory is evolved. The tactics that gained one victory are not repeated. Method follows the circumstances, as water runs away from high places and hastens downwards. War avoids what is strong and strikes at what is weak. Water shapes its course according to the ground it flows over. The soldier works out his victory in relation to the foe he is facing. Water retains no constant shape, and in warfare there are no constant conditions. He who can modify his tactics in relation to his opponent, and win by that change, may be called a heaven-born captain. The five elements take turns. The seasons make way. Days lengthen and shorten. The moon wanes and waxes.
Coming Up in Chapter 7
Chapter VII on Maneuvering turns indirect routes into timely arrival, keeps supplies from collapsing the march, and uses drums and signals so a large host moves as one body without exposing the plan to scouts.
