Chapter 9

modern paraphrase of Lionel Giles's 1910 translation

[The content of this interesting chapter is better described in §1 than by this heading.]

Sun Tzŭ said: We now come to the matter of encamping the army and observing signs of the enemy. Cross mountains quickly, and stay near valleys.

[The point is not to linger on barren high ground, but to stay close to water and pasture. Compare Wu Tzŭ, ch. 3: “Do not stay in natural ovens,” meaning “the mouths of valleys.” Chang Yu tells this story: Wu-tu Ch’iang was a bandit chief during the Later Han, and Ma Yuan was sent to wipe out his band. When Ch’iang took refuge in the hills, Ma Yuan made no effort to force a battle but seized all the key positions controlling water and forage. Soon Ch’iang was so desperate for supplies that he had to surrender unconditionally. He did not understand the value of staying near valleys.]

Camp on high ground,

[Not on high mountains, but on knolls or low hills rising above the surrounding land.]

facing the sun.

[Tu Mu reads this as “facing south,” and Ch’en Hao as “facing east.” Compare §§11, 13 below.]

Do not climb heights to fight. So much for mountain warfare.

After crossing a river, move well away from it.

[“To tempt the enemy to cross after you,” according to Ts’ao Kung, and also, says Chang Yu, “so that your maneuvers are not hindered.” The T’ung Tien reads, “If the enemy crosses a river,” etc., but given the next sentence, this is almost certainly an interpolation.]

When an invading force crosses a river to advance, do not meet it in midstream. It is better to let half their army get across and then attack.

[Li Ch’uan refers to Han Hsin’s great victory over Lung Chu at the Wei River. The Ch’ien Han Shu, ch. 34, describes the battle this way: “The two armies were drawn up on opposite banks. At night, Han Hsin had his men fill some ten thousand sacks with sand and build a dam upstream. Then, leading half his army across, he attacked Lung Chu; after a while he pretended to fail and quickly withdrew to the other side. Lung Chu, elated by this unexpected success, cried, ‘I always knew Han Hsin was a coward!’ and pursued him, beginning to cross the river in turn. Han Hsin then sent men to cut open the sandbags, releasing a flood that swept down and prevented most of Lung Chu’s army from crossing. He then turned on the portion already across and destroyed it, killing Lung Chu himself. The rest of the army on the far bank scattered and fled in all directions.”]

If you want to fight, do not meet the invader near a river he must cross.

[For fear of preventing his crossing.]

Anchor your craft upstream from the enemy and facing the sun.

[See §2 above. Repeating these words in the context of water is awkward. Chang Yu notes: “This refers either to troops arrayed on a riverbank or to boats anchored on the river itself; in either case, it is essential to be upstream of the enemy and facing the sun.” The other commentators are not very clear.]

Do not move upstream to engage the enemy.

[Tu Mu says: “Since water flows downward, we must not camp downstream, for fear the enemy may open sluices and flood us out. Chu-ko Wu-hou observed that ‘in river warfare we must not advance against the current,’ meaning our fleet should not be anchored downstream of the enemy’s, since they could ride the current to crush us.” Other commentators also warn that the enemy may poison the water upstream so it floats down to us.]

So much for river warfare.

When crossing salt marshes, your only goal should be to get over them quickly, without delay.

[Because of the lack of fresh water, the poor pasture, and not least because they are low, flat, and exposed to attack.]

If forced to fight in a salt marsh, position yourself near water and grass, with your back to a cluster of trees.

[Li Ch’uan notes that ground with trees is less likely to be treacherous, while Tu Mu says they protect the rear.]

So much for operations in salt marshes.

In dry, level country, take an easily accessible position with rising ground to your right and rear,

[Tu Mu quotes T’ai Kung: “An army should have a stream or marsh on its left and a hill or mound on its right.”]

so that danger lies in front and safety behind. So much for campaigning in flat country.

These are the four useful branches of military knowledge

[Those concerned with (1) mountains, (2) rivers, (3) marshes, and (4) plains. Compare Napoleon’s “Military Maxims,” no. 1.]

that enabled the Yellow Emperor to defeat four rival sovereigns.

[On the “Yellow Emperor”: Mei Yao-ch’en plausibly asks whether the text has an error, since nothing is recorded of Huang Ti conquering four other Emperors. The Shih Chi (ch. 1, opening) speaks only of his victories over Yen Ti and Ch’ih Yu. The Liu T’ao mentions that he “fought seventy battles and pacified the Empire.” Ts’ao Kung explains that the Yellow Emperor first instituted the feudal system of vassal princes, each of whom (four in number) originally bore the title of Emperor. Li Ch’uan tells us the art of war began under Huang Ti, who received it from his Minister Feng Hou.]

All armies prefer high ground to low,

[“High ground,” says Mei Yao-ch’en, “is not only more pleasant and healthier but also militarily more convenient; low ground is damp and unhealthy and also poor for fighting.”]

and sunny places to dark.

If you take care of your men,

[Ts’ao Kung says: “Head for fresh water and pasture, where you can let your animals graze.”]

and camp on firm ground, the army will be free of disease,

[Chang Yu says: “The dry climate will prevent outbreaks of illness.”]

and this means victory.

When you come to a hill or embankment, occupy the sunny side, with the slope on your right rear. This benefits your soldiers and makes use of the ground’s natural advantages.
When heavy rains upstream have swollen a river you wish to ford until it runs flecked with foam, wait until it subsides.
Country with sheer cliffs and torrents running between, deep natural hollows,

[Defined as “places enclosed on every side by steep banks, with pools of water at the bottom.”]

confined places,

[Defined as “natural pens or prisons” or “places ringed on three sides by precipices—easy to enter, hard to leave.”]

tangled thickets,

[Defined as “places so densely overgrown that spears cannot be used.”]

quagmires

[Defined as “low places so heavy with mud that chariots and horsemen cannot pass.”]

and crevasses

[Defined by Mei Yao-ch’en as “a narrow, difficult passage between overhanging cliffs.” Tu Mu’s note is “ground covered with trees and rocks, cut by numerous ravines and pitfalls.” This is vague, but Chia Lin clearly explains it as a defile or narrow pass, and Chang Yu agrees. On balance, the commentators favor “defile.” But the ordinary meaning of the Chinese in one place is “a crack or fissure,” and since the Chinese elsewhere in the sentence already indicates something like a defile, I think Sun Tzŭ here means crevasses.]

should be left as quickly as possible and not approached.

While we keep clear of such places, we should get the enemy to approach them; while we face them, we should make sure the enemy has them at his back.
If near your camp there is hilly ground, ponds bordered by water-grass, hollows full of reeds, or woods with thick undergrowth, they must be thoroughly searched, for these are places where ambushers or sneaky spies are likely to be hiding.

[Chang Yu notes: “We must also guard against traitors lying in close cover, secretly observing our weaknesses and listening to our orders.”]

When the enemy is close and keeps still, he is relying on the natural strength of his position.

[Here Sun Tzŭ begins his remarks on reading signs, much of it so sound that it might appear in a modern manual like General Baden-Powell’s “Aids to Scouting.”]

When he stays at a distance and tries to provoke battle, he wants the other side to advance.

[Probably because we hold a strong position from which he wants to draw us out. “If he came up close and tried to force a fight,” says Tu Mu, “he would seem to scorn us, and we would be less likely to take the bait.”]

If his camp is easy to reach, he is offering a lure.
Movement among the trees of a forest shows the enemy is advancing.

[Ts’ao Kung explains this as “felling trees to clear a path,” and Chang Yu says: “Every commander sends scouts to climb high places and watch the enemy. If a scout sees the trees of a forest shaking and moving, he knows they are being cut down to clear a path for the enemy’s march.”]

The appearance of many screens in the middle of thick grass means the enemy wants to make us suspicious.

[Tu Yu’s explanation, borrowed from Ts’ao Kung, is this: “Many screens or shelters in the middle of thick vegetation is a sure sign the enemy has fled and, fearing pursuit, has built these hiding places to make us suspect an ambush.” Apparently these “screens” were hastily knotted together from any tall grass the retreating enemy came across.]

Birds suddenly taking flight reveal an ambush.

[Chang Yu’s explanation is surely right: “When birds flying in a straight line suddenly shoot upward, it means soldiers are in ambush at the spot beneath.”]

Startled animals mean a sudden attack is coming.

When dust rises in a high column, chariots are approaching; when the dust is low but spread over a wide area, infantry is coming.

[“High and sharp,” or rising to a peak, is admittedly exaggerated for dust. The commentators explain that horses and chariots, being heavier than men, raise more dust and follow each other in the same wheel-track, while foot soldiers march in ranks many abreast. Chang Yu says, “Every army on the march must have scouts well in advance, who on seeing dust raised by the enemy will gallop back and report it to the commander-in-chief.” Compare General Baden-Powell: “As you move along, say, in hostile country, your eyes should be looking afar for the enemy or any signs of him: figures, dust rising, birds getting up, glitter of arms, etc.”]

When the dust branches off in different directions, it means parties have been sent to collect firewood. A few small clouds of dust drifting back and forth mean the army is making camp.

[Chang Yu says: “In setting up defenses for a camp, light cavalry are sent out to survey the position and identify the weak and strong points around its perimeter. Hence the small amount of dust and its movement.”]

Humble language coupled with increased preparations mean the enemy is about to attack.

[“As if greatly afraid of us,” says Tu Mu. “Their aim is to make us complacent and careless, then strike.” Chang Yu cites the story of T’ien Tan of Ch’i-mo against the Yen forces under Ch’i Chieh. In ch. 82 of the Shih Chi we read: “T’ien Tan openly said: ‘My only fear is that the Yen army may cut off the noses of their Ch’i prisoners and put them in the front rank against us; that would be the ruin of our city.’ The other side, hearing this, immediately acted on the suggestion; but the people inside the city, enraged at seeing their countrymen mutilated, and fearing only that they might fall into enemy hands, were stirred to defend themselves all the more stubbornly. Once again T’ien Tan sent over double agents who told the enemy: ‘What I dread most is that the men of Yen may dig up our ancestral tombs outside the town and dishonor our forefathers, breaking our spirit.’ The besiegers promptly dug up all the graves and burned the corpses. The people