The relative size of your force as against that of your adversary is by itself of no consequence. What controls is the relative size of your force at the point where you join in battle. You can strike with the few and be many if you strike your adversary in his gaps. Seek out places where the defense is not strict, the place not tightly guarded, the generals weak, the troops disorderly, the supplies are scarce and the forces are isolated.

Kill one, terrify a thousand.

Attack is the secret of defense; defense is the planning of an attack.

He whose ranks are united in purpose will be victorious.

And regulation entails organizational effectiveness, a chain of command, and a structure for logistical support.

Spies are a most important element in water, because on them depends an army's ability to move.

Hence the saying: If you know the enemy and you know yourself, your victory will not stand in doubt; if you now Heaven and you know Earth, you may make your victory complete.