Weaknesses and Strengths
(xu shi 1)
Generally, he who first occupies the field of battle and awaits his enemy is rested and prepared; he who comes late to the scene and hastens into battle is weary and passive. Therefore, those skilled in war move the enemy rather than being moved by him.
Those who are able to make the enemy come voluntarily to the designated place do so by offering him some gain. And those who are able to keep him from coming do so by creating obstacles and inflicting damage on him. Thus, when the enemy is rested, tire him; when well fed, starve him; and when settled, get him on the move. All this is possible because you appear at places the enemy cannot come to the rescue of and least expects you. That you may march a thousand li without tiring yourself is because you are passing through territory where there is no enemy to stop you. That you are certain to take what you attack is because you attack a place the enemy cannot protect. That you are certain of success in holding what you defend is because you defend a place the enemy finds impregnable.
Therefore, against the expert in attack, the enemy does not know where to defend; and against the expert in defense, the enemy does not know where to attack. So subtle is the expert that he leaves no trace, so mysterious that he makes no sound. Thus, he becomes the arbiter of his enemy’s fate. His advance is irresistible because he plunges into his enemy’s weak position; and his withdrawal cannot be overtaken because it is so swift. Thus, when we wish to give battle, the enemy cannot but leave his position to engage us even though he is safe behind high walls and deep moats, because we attack a position he must rescue. When we wish to avoid battle, we may simply draw a line on the ground by way of defense and the enemy cannot engage us because we have diverted him to a different target.
Hence, if we are able to determine the enemy’s disposition while concealing our own, then we can concentrate our forces while his are dispersed. And if our forces are concentrated at one place while his are scattered at ten places, then it is ten to one when we attack him at one place. This means we will be numerically superior. If we are able to use many to strike few at a selected point, those we deal with will be greatly reduced in number. The enemy must not know where we intend to give battle, for if he doesn’t know where we intend to give battle, he must prepare in a great many places and, when he does that, those we have to fight in any one place will be few in number. Thus if the enemy makes preparations by reinforcing his front, his rear will be weakened; and if he makes preparations by reinforcing his rear, his front will be weakened. If he does this to defend his left, his right will be weakened; and if his right, his left will be weakened. To be prepared everywhere is to be weak everywhere. One who has to prepare against the enemy everywhere is bound to be weak; one who makes the enemy prepare against him everywhere is bound to be strong.
Therefore if one knows when and where a battle will be fought, his troops can march a thousand li to fight the enemy. But if one knows neither the battleground nor the date of battle, his left flank will not be able to rescue his right, nor the other way around. Similarly his front will not be able to support his rear, and vice versa. How much more so if his reinforcements are scores of li away, and even the closest are separated by several li! In my view, while the troops of Yue (tr.: a neighboring state of Wu) are numerous, that alone does not determine the outcome of war. Therefore, I say: victory can be created. Even if the enemy is numerically stronger, we can render it impotent.
So one must analyze the enemy’s plan in order to have a clear understanding of his strong and weak points. Provoke the enemy into action so as to ascertain his pattern of movement. Lure him into the open so as to find out the vulnerable spots in his disposition. Probe him so as to learn where his strength is abundant and where deficient. Now the ultimate in troop disposition is to leave no trace of how they are disposed. In this way, even the cleverest spy cannot detect anything, nor can the best brains succeed in scheming against us. Even if we show people the flexible tactics we used to gain victory in conformity with the changing enemy situation, they still cannot comprehend them. The enemy may know the tactics by which we win, but he does not know how we use the tactics to defeat him. Following each victory, we do not repeat the same tactics. We change them constantly to suit the changing circumstances.
Now the law governing military operations is as that governing the flow of water, which always evades high points, choosing lower ones instead. To operate the army successfully, we must avoid the enemy’s strong points and seek out his weak points. As the water changes its course in accordance with the contours of the terrain, so a warrior changes his tactics in accordance with the enemy’s changing situation. There is no fixed pattern in the use of tactics in war, just as there is no constant course in the flow of water. He who wins modifies his tactics in accordance with the changing enemy situation and this works miracles.
None of the five elements of nature (wuxing 2) is ever predominant, and none of the four seasons lasts forever. Some days are longer and some shorter. The moon waxes and wanes.
1 Xu and shi as military terminology used in ancient China are a pair of opposites. Xu denotes weakness, dispersion and numerical inferiority, while shi denotes strength, concentration and numerical superiority. In military, tactics, the combined use of xu and shi denotes the use of feint and other deceptive moves to confuse and overpower the enemy
2 Wuxing, a terminology first used by philosophers of the yin-yang school to characterize the universe. It contains five elements, bearing the characteristics of: wood, fire, earth, metal and water. Each is supposed to prevail over another only to be prevailed over.