Tu Mu says 所以委質來謝此乃勢已窮或有他故必欲休息也 “If the enemy open friendly relations by sending hostages, it is a sign that they are anxious for an armistice, either because their strength is exhausted or for some other reason.” But it hardly needs a Sun Tzŭ to draw such an obvious inference; and although Tu Mu is supported by Mei Yao-ch‘ên and Chang Yu, I cannot think that hostages are indicated by the word 委.
39. If the enemy's troops march up angrily and remain facing ours for a long time without either joining battle or taking themselves off again, the situation is one that demands great vigilance and circumspection.
Capt. Calthrop falls into a trap which often lurks in the word 相. He translates: “When both sides, eager for a fight, face each other for a considerable time, neither advancing nor retiring,” etc. Had he reflected a little, he would have seen that this is meaningless as addressed to a commander who has control over the movements of his own troops. 相迎, then, does not mean that the two armies go to meet each other, but simply that the other side comes up to us. Likewise with 相去. If this were not perfectly clear of itself, Mei Yao-ch‘ên’s paraphrase would make it so: 怒而來逆我, etc. As Ts‘ao Kung points out, a manœuvre of this sort may be only a ruse to gain time for an unexpected flank attack or the laying of an ambush.
40. If our troops are no more in number than the enemy, that is amply sufficient;
Wang Hsi’s paraphrase, partly borrowed from Ts‘ao Kung, is 權力均足矣. Another reading, adopted by Chia Lin and the T‘u Shu, is 兵非貴益多, which Capt. Calthrop renders, much too loosely: “Numbers are no certain mark of strength.”
it only means that no direct attack can be made.
Literally, “no martial advance.” That is to say, 正 “chêng” tactics and frontal attacks must be eschewed, and stratagem resorted to instead.
What we can do is simply to concentrate all our available strength, keep a close watch on the enemy, and obtain reinforcements.