These are the words of Master Sun:
You should conquer the territory of your enemy without destroying the land. To conquer through destruction is not wise.
It is better to capture an army than to destroy it, and the same is true of a battalion, a regiment, and even a unit of enemy soldiers. It is thus not the hallmark of a great commander to win many battles. Rather, a great commander subjugates the enemy without engaging in battle.
When war is fought, the best course of action is to foil the plans of the enemy. The second best course of action is to stop the enemy from mustering his forces. The third best course of action is to attack the army of the enemy in the field of battle. Finally, the worst course of action is to attack fortified cities.
The main rule is this: Avoid laying siege to fortified cities if this is at all possible. The construction of the equipment needed for a successful siege, such as movable shelters, will take upwards of three months, and the building of ramps up against the city walls will take another three months. An impatient commander will all too easily find himself ordering an attack too early, and like ants his troops will throw themselves against the walls of the fortified city, and the commander will lose a third of his soldiers while leaving the enemy city unscathed. This is how catastrophic an ill-prepared siege can become.
The wise sovereign defeats his enemies without battle, conquers the cities of his enemies without having to besiege them, and overthrows his enemies without waging prolonged campaigns. Thus saving his strength, the wise sovereign may dare to seek to rule the entire Realm, and if he can do so without losing a single man, his triumph will be supreme. This is the strategy of the sovereign who has mastered the art of war.
In tactical maneuvering, the following rules apply:
Even if a small army fights with great honor, it will be captured and defeated by a greater force in the end.
The skillful commander is the bulwark of the state. Thus, if its commander is unmatched in every way, the state will be strong. If, however, its commander is of poor caliber, the state will be weak.
A sovereign can bring misfortune upon his own army in three ways:
A sovereign who thus hobbles his army and weakens its discipline and resolve will soon find himself targeted by enemies from near and far. This is the origin of the old proverb: "Anarchy within the army is the fountainhead of defeat."
A skillful commander will know these five essential truths of strategy:
If you know your enemy and yourself, you can fight a hundred battles with no fear of defeat. If you only know yourself but not your enemy, you will suffer as many defeats as you will achieve victories. If you know neither yourself nor your enemy, you will find yourself defeated in every battle.