Those who are victorious plan effectively and change decisively. They are like a great river that maintains its course but adjusts its flow...they have form but are formless. They are skilled in both planning and adapting and need not fear the result of a thousand battles: for they win in advance, defeating those that have already lost.
There are three ways in which a ruler can bring misfortune on his army: By commanding the army to advance or to retreat, being ignorant of the fact that it cannot obey. This is called hobbling the army. By attempting to govern an army in the same way as he administers a kingdom, being ignorant of the conditions which obtain in an army. This causes restlessness in the soldier's minds. By employing the officers of his army without discrimination, through ignorance of the military principle of adaptation to circumstances. This shakes the confidence of the soldiers.
For the wise man delights in establishing his merit, the brave man likes to show his courage in action, the covetous man is quick at seizing advantages, and the stupid man has no fear of death.
Do not press an enemy at bay. Prince Fu Ch'ai said: "Wild beasts, when at bay, fight desperately. How much more is this true of men! If they know there is no alternative, they will fight to the death.
So the principles of warfare are: Do not depend on the enemy not coming, but depend on our readiness against him. Do not depend on the enemy not attacking, but depend on our position that cannot be attacked.
An army may be likened to water, for just as flowing water avoids the heights and hastens to the lowlands, so an army avoids strength and strikes weakness.
And therefore only the enlightened sovereign and the worthy general who are able to use the most intelligent people as agents are certain to achieve great things.