In all fighting, the direct method may be used for joining battle, but indirect methods will be needed in order to secure victory. In battle, there are not more than two methods of attack.. the direct and the indirect; yet these two in combination give rise to an endless series of maneuvers.
Factors in the art of warfare are: First, calculations; second, quantities; third, logistics; fourth, the balance of power; and fifth, the possibility of victory is based on the balance of power.
An army may be likened to water, for just as flowing water avoids the heights and hastens to the lowlands, so an army avoids strength and strikes weakness.
There are three ways in which a ruler can bring misfortune on his army: By commanding the army to advance or to retreat, being ignorant of the fact that it cannot obey. This is called hobbling the army. By attempting to govern an army in the same way as he administers a kingdom, being ignorant of the conditions which obtain in an army. This causes restlessness in the soldier's minds. By employing the officers of his army without discrimination, through ignorance of the military principle of adaptation to circumstances. This shakes the confidence of the soldiers.
The General who in advancing does not seek personal fame, and in withdrawing is not concerned with avoiding punishment, but whose only purpose is to protect the people and promote the best interests of his sovereign, is the precious jewel of the state.
When your weapons are dulled and ardour damped, your strength exhausted and treasure spent, neighboring rulers will take advantage of your distress to act. And even though you have wise counsellors, none will be able to lay good plans for the future. Thus, while we have heard of blundering swiftness in war, we have not yet seen a clever operation that was prolonged.
Those skilled at making the enemy move do so by creating a situation to which he must conform; they entice him with something he is certain to take, and with lures of ostensible profit they await him in strength.
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.