The general who wins the battle makes many calculations in his temple before the battle is fought. The general who loses makes but few calculations beforehand.
Thus we may know that there are five essentials for victory: He will win who knows when to fight and when not to fight. He will win who knows how to handle both superior and inferior forces. He will win whose army is animated by the same spirit throughout all its ranks. He will win who, prepared himself, waits to take the enemy unprepared. He will win who has military capacity and is not interfered with by the sovereign.
Fighting with a large army under your command is nowise different from fighting with a small one: it is merely a question of instituting signs and signals.
It is through the dispositions of an army that its condition may be discovered. Conceal your dispositions, and your condition will remain secret, which leads to victory,; show your dispositions, and your condition will become patent, which leads to defeat.
Generally, management of many is the same as management of few. It is a matter of organization. And to control many is the same as to control few. This is a matter of formations and signals.
Military tactics are like unto water; for water in its natural course runs away from high places and hastens downwards... Water shapes its course according to the nature of the ground over which it flows; the soldier works out his victory in relation to the foe whom he is facing. Therefore, just as water retains no constant shape, so in warfare there are no constant conditions. He who can modify his tactics in relation to his opponent and thereby succeed in winning, may be called a heaven-born captain.
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.