Build your opponent a golden bridge to retreat across.

He who wishes to fight must first count the cost

Other conditions being equal, if one force is hurled against another ten times its size, the result will be the flight of the former.

Ground which can be abandoned but is hard to re-occupy is called entangling.

The proximity of an army causes prices to go up; and high prices cause people's substance to be drained away. When their substance is drained away, they will be afflicted by heavy exactions. With this loss of substance and exhaustion of strength, the homes of the people will be stripped bare, and their incomes dissipated.

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.

If the enemy leaves a door open, you must rush in.