Thus a great warrior takes control of others and does not let others control him. By holding out temptation, he can make the enemy approach; by inflicting harm, he can hold them at a distance. Using the same principles, if the enemy are taking their ease, he can rouse them; if they are well-provisioned, he can starve them; if they are encamped, he can move them on. Attack at points which the enemy must scramble to defend, and launch lightning attacks where they are not expected. It is possible to march your army a thousand li as long as it is across unoccupied territory. To be sure of success, only attack at undefended areas. To be sure in defense, mount your defenses at those places the enemy cannot attack.
~ Sun Tzu, The Art of War