(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 王子 as saying: 指授在君決戰在將也 “It is the sovereign’s function to give broad instructions, but to decide on battle 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 any central authority,—that he was, in fact, 將 and 君 in one.
Victory lies in the knowledge of these five points.
Literally, “These five things are knowledge of the principle of victory.”
18. 故曰知彼知己百戰不殆不知彼而知己一勝一負不知彼不知己每戰必殆
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‘üan cites the case of 苻堅 Fu Chien, prince of 秦 Ch‘in, who in 383 A.D. marched with a vast army against the 晉 Chin Emperor. When warned not to despise an enemy who could command the services of such men as 謝安 Hsieh An and 桓沖 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 淝 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.
The modern text, represented by the 北堂書鈔 and T‘u Shu, has 必敗, which I should be inclined to adopt in preference to 殆 here, though the T‘ung Tien and Yü Lan both have the latter. Chang Yü offers the best commentary on 知彼知己. He says that these words “have reference to attack and defence: knowing the enemy enables you to take the offensive, knowing yourself enables you to stand on the defensive.” He adds: 攻是守之機守是攻之策 “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.