15. In war, practice dissimulation, and you will succeed.
According to Tu Mu, 立 stands for 立勝. Cf. I. § 18. In the tactics of Turenne, deception of the enemy, especially as to the numerical strength of his troops, took a very prominent position.
Move only if there is a real advantage to be gained.
This is the interpretation of all the commentators except Wang Hsi, who has the brief note 誘之也 “Entice out the enemy” (by offering him some apparent advantage).
16. Whether to concentrate or to divide your troops, must be decided by circumstances.
17. Let your rapidity be that of the wind,
The simile is doubly appropriate, because the wind is not only swift but, as Mei Yao-ch‘ên points out, 無形跡 “invisible and leaves no tracks.”
your compactness that of the forest.
It is hardly possible to take 徐 here in its ordinary sense of “sedate,” as Tu Yu tries to do. Mêng Shih comes nearer the mark in his note 緩行須有行列 in “When slowly marching, order and ranks must be preserved” — so as to guard against surprise attacks. But natural forests do not grow in rows, whereas they do generally possess the quality of density or compactness. I think then that Mei Yao-ch‘ên uses the right adjective in saying 如林之森然.
18. In raiding and plundering be like fire,
Cf. Shih Ching, IV. 3. iv. 6: 如火烈烈則莫我敢曷 “Fierce as a blazing fire which no man can check.”
in immovability like a mountain.
That is, when holding a position from which the enemy is trying to dislodge you, or perhaps, as Tu Yu says, when he is trying to entice you into a trap.
- For a number of maxims on this head, see “Marshal Turenne” (Longmans, 1907), p. 29.)