There is no difference between administering many troops and few troops. It is a matter of organization, of instituting layers of control. There is no difference between commanding a large army and a small one. It is a matter of communications, of establishing an efficient system of command signals. Thanks to the combined use of qi and zheng tactics1, the army is able to withstand the onslaught of the enemy forces. By staying clear of the enemy’s strong points and striking at his weak points, it is able to fall upon the enemy like using a whetstone to crush an egg.
Generally, in battle, use zheng to engage the enemy and use qi to score victory. The resourcefulness of those skilled in the use of qi is as inexhaustible as heaven and earth and as unending as the flow of rivers; it is like the sun and the moon which end their course only to begin anew, like the four seasons which pass only to return once more. There are no more than five tones in music, yet their combinations give rise to countless melodies. There are no more than five primary colors, yet in combination, they produce innumerable hues. There are no more than five flavors, yet their blends produce endless varieties. In military tactics, there are only two types of operation, qi and zheng, yet their variations are limitless. They constantly change from one to the other, like moving in a circle with neither a beginning nor an end. Who can exhaust their possibilities?
When torrential water moves boulders, it is because of its momentum. When falcons strike and destroy their prey, it is because of perfect timing. Thus, when launching an offensive, a good commander creates a good posture which provides him with an irresistible momentum and when he attacks, it is with lightning speed. The momentum is similar to that of a fully-drawn crossbow, the speed to that of the arrow leaving the bow.
Amidst the chaos of men and horses locked in battle beneath waving banners, there must be no disorder in command. The troops may appear to be milling about in circles, but they should be arrayed in a way that guarantees them against defeat. To simulate disorder, there must be strict organization. To simulate fear, there must be great courage. To simulate weakness, there must be strength. Order comes from organization, courage from momentum, and strength from disposition. Thus, those who are skilled in keeping the enemy on the move puzzle him with deceptive appearances according to which he will react. They lure the enemy with baits which he is certain to take. In so doing, they keep the enemy on the move and pounce on him at the right moment.
Therefore, one who is skilled at directing war always tries to turn the situation to his advantage rather than make excessive demands on his subordinates. Hence, he is able to select the right men and exploit the situation.
He who is skilful in turning the situation to his advantage can send his men into battle as he would roll logs or rocks. Logs and rocks remain immobile when they are on level ground, but roll forward when on a steep slope. The square ones do not move. The round ones roll with agility. Thus the strategic advantage of troops skillfully commanded in battle may be compared to the momentum of round boulders rolling down from mountain heights.
1 Qi and zheng, as military terminology used in ancient China, are a pair of opposites. Generally, qi denotes the use of unusual and unexpected methods, of sudden, surprise attacks, of flanking movements in military operations; while zheng denotes the use of normal and regular methods, of frontal attacks and defensive moves in military operations.