Because then, as Tu Yu observes, 皆制在我然後出奇以制敵 “the initiative will lie with us, and by making sudden and unexpected attacks we shall have the enemy at our mercy.” The commentators make a great pother about the precise meaning of 盈, which to the foreign reader seems to present no difficulty whatever.
9. 若敵先居之盈而勿從不盈而從之
Should the enemy forestall you in occupying a pass, do not go after him if the pass is fully garrisoned, but only if it is weakly garrisoned.
10. 險形者我先居之必居高陽以待敵
With regard to precipitous heights, if you are beforehand with your adversary, you should occupy the raised and sunny spots, and there wait for him to come up.
Ts‘ao Kung says: 地形險隘尤不可致於人 “The particular advantage of securing heights and defiles is that your actions cannot then be dictated by the enemy.” [For the enunciation of the grand principle alluded to, see [VI. § 2]]. Chang Yü tells the following anecdote of 裴行儉 P‘ei Hsing-chien (A.D. 619–682), who was sent on a punitive expedition against the Turkic tribes. “At nightfall he pitched his camp as usual, and it had already been completely fortified by wall and ditch, when suddenly he gave orders that the army should shift its quarters to a hill near by. This was highly displeasing to his officers, who protested loudly against the extra fatigue which it would entail on the men. P‘ei Hsing-chien, however, paid no heed to their remonstrances and had the camp moved as quickly as possible. The same night, a terrific storm came on, which flooded their former place of encampment to the depth of over twelve feet. The recalcitrant officers were amazed at the sight, and owned that they had been in the wrong. ‘How did you know what was going to happen?’ they asked. P‘ei Hsing-chien replied: ‘From this time forward be content to obey orders without asking unnecessary questions.’ [See Chiu T‘ang Shu, ch. 84, fol. 12 ro, and Hsin T‘ang Shu, ch. 108, fol. 5 vo.] From this it may be seen,” Chang Yü continues, “that high and sunny places are advantageous not only for fighting, but also because they are immune from disastrous floods.”
11. 若敵先居之引而去之勿從也
If the enemy has occupied them before you, do not follow him, but retreat and try to entice him away.
The turning-point of 李世民 Li Shih-min’s campaign in 621 A.D. against the two rebels, 竇建德 Tou Chien-tê, King of 夏 Hsia, and 王世充 Wang Shih-ch‘ung, Prince of 鄭 Chêng, was his seizure of the heights of 武牢 Wu-lao, in spite of which Tou Chien-tê persisted in his attempt to relieve his ally in Lo-yang, was defeated and taken prisoner. [See Chiu T‘ang Shu, ch. 2, fol. 5 vo and also ch. 54.]
12. 遠形者勢均難以挑戰戰而不利