[This is not merely the general’s ability to estimate numbers correctly, as Li Ch’uan and others make out. Chang Yu expounds the saying more satisfactorily: "By applying the art of war, it is possible with a lesser force to defeat a greater, and _vice versa_. The secret lies in an eye for locality, and in not letting the right moment slip. Thus Wu Tzŭ says: ‘With a superior force, make for easy ground; with an inferior one, make for difficult ground.’"] (3) He will win whose army is animated by the same spirit throughout all its ranks. (4) He will win who, prepared himself, waits to take the enemy unprepared. (5) He will win who has military capacity and is not interfered with by the sovereign. [Tu Yu quotes Wang Tzŭ as saying: "It is the sovereign’s function to give broad instructions, but to decide on battle it is the function of the general." It is needless to dilate on the military disasters which have been caused by undue interference with operations in the field on the part of the home government. Napoleon undoubtedly owed much of his extraordinary success to the fact that he was not hampered by central authority.] Victory lies in the knowledge of these five points. [Literally, “These five things are knowledge of the principle of victory.”] 18. Hence the saying: If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. [Li Ch’uan cites the case of Fu Chien, prince of Ch’in, who in 383 A.D. marched with a vast army against the Chin Emperor. When warned not to despise an enemy who could command the services of such men as Hsieh An and Huan Ch’ung, he boastfully replied: "I have the population of eight provinces at my back, infantry and horsemen to the number of one million; why, they could dam up the Yangtsze River itself by merely throwing their whips into the stream. What danger have I to fear?" Nevertheless, his forces were soon after disastrously routed at the Fei River, and he was obliged to beat a hasty retreat.] If you know neither the enemy nor yourself, you will succumb in every battle. [Chang Yu said: "Knowing the enemy enables you to take the offensive, knowing yourself enables you to stand on the defensive." He adds: "Attack is the secret of defence; defence is the planning of an attack." It would be hard to find a better epitome of the root-principle of war.] Chapter IV. TACTICAL DISPOSITIONS