With regard to precipitous heights, if you are beforehand with your adversary, you should occupy the raised and sunny spots, and there wait for him to come up.
Carefully study the well-being of your men, and do not overtax them. Concentrate your energy and hoard your strength. Keep your army continually on the move, and devise unfathomable plans.
When the enemy is at ease, be able to weary him; when well fed, to starve him; when at rest, to make him move. Appear at places to which he must hasten; move swiftly where he does not expect you.
The enemy's spies who have come to spy on us must be sought out, tempted with bribes, led away and comfortably housed. Thus they will become double agents and available for our service. It is through the information brought by the double agent that we are able to acquire and employ local and inward spies. It is owing to his information, again, that we can cause the doomed spy to carry false tidings to the enemy.
We cannot enter into alliances until we are acquainted with the designs of our neighbors. We are not fit to lead an army on the march unless we are familiar with the face of the country.