Chapter 9: The Army on the March

IX. THE ARMY ON THE MARCH

[The contents of this interesting chapter are better
indicated in ss. 1 than by this heading.]

1. Sun Tzu said: We come now to the question of encamping
the army, and observing signs of the enemy. Pass quickly over
mountains, and keep in the neighborhood of valleys.

[The idea is, not to linger among barren uplands, but to
keep close to supplies of water and grass. Cf. Wu Tzu, ch. 3:
"Abide not in natural ovens," i.e. "the openings of valleys."
Chang Yu tells the following anecdote: Wu-tu Ch'iang was a
robber captain in the time of the Later Han, and Ma Yuan was sent
to exterminate his gang. Ch'iang having found a refuge in the
hills, Ma Yuan made no attempt to force a battle, but seized all
the favorable positions commanding supplies of water and forage.
Ch'iang was soon in such a desperate plight for want of
provisions that he was forced to make a total surrender. He did
not know the advantage of keeping in the neighborhood of
valleys."]

2. Camp in high places,

[Not on high hills, but on knolls or hillocks elevated above
the surrounding country.]

facing the sun.

[Tu Mu takes this to mean "facing south," and Ch'en Hao
"facing east." Cf. infra, SS. 11, 13.

Do not climb heights in order to fight. So much for mountain
warfare.
3. After crossing a river, you should get far away from it.

["In order to tempt the enemy to cross after you," according
to Ts'ao Kung, and also, says Chang Yu, "in order not to be
impeded in your evolutions." The T'UNG TIEN reads, "If THE ENEMY
crosses a river," etc. But in view of the next sentence, this is
almost certainly an interpolation.]

4. When an invading force crosses a river in its onward
march, do not advance to meet it in mid-stream. It will be best
to let half the army get across, and then deliver your attack.

[Li Ch'uan alludes to the great victory won by Han Hsin over
Lung Chu at the Wei River. Turning to the CH'IEN HAN SHU, ch.
34, fol. 6 verso, we find the battle described as follows: "The
two armies were drawn up on opposite sides of the river. In the
night, Han Hsin ordered his men to take some ten thousand sacks
filled with sand and construct a dam higher up. Then, leading
half his army across, he attacked Lung Chu; but after a time,
pretending to have failed in his attempt, he hastily withdrew to
the other bank. Lung Chu was much elated by this unlooked-for
success, and exclaiming: "I felt sure that Han Hsin was really a
coward!" he pursued him and began crossing the river in his turn.
Han Hsin now sent a party to cut open the sandbags, thus
releasing a great volume of water, which swept down and prevented
the greater portion of Lung Chu's