Chapter 13

1. Sūnzǐ said: Raising an army of a hundred thousand men and marching them long distances inflicts heavy losses on the people and drains the resources of the State. The daily cost will reach a thousand ounces of silver.

[Compare II. §§ 1, 13, 14.]

There will be turmoil at home and abroad, and men will collapse from exhaustion along the roads.

[Compare the Tao Te Ching, ch. 30: “Where troops have camped, brambles and thorns spring up.” Chang Yu comments: “One might recall the saying: ‘On serious ground, gather plunder.’ Why then should transport cause exhaustion on the roads? The answer is that not only food, but all kinds of military supplies must be carried to the army. Furthermore, the order to ‘forage on the enemy’ only means that when an army is deep in hostile territory, it must guard against shortages of food. So, without relying solely on the enemy for grain, we must forage in order to keep supplies flowing without interruption. Then again, in places like salt deserts where food cannot be obtained, supplies from home cannot be done without.”]

As many as seven hundred thousand families will be hindered in their work.

[Mei Yao-ch’en says: “Men will be missing from the plough.” This refers to the system of dividing land into nine plots of about 15 acres each, with the central plot worked on behalf of the State by the tenants of the other eight. Tu Mu tells us their cottages were also built here, with a well dug for common use. [See II. § 12, note.] In wartime, one family of every eight had to serve in the army, while the other seven supported it. So a levy of 100,000 men (one able-bodied soldier per family) would disrupt the farming of 700,000 families.]

2. Opposing armies may face each other for years, struggling for a victory decided in a single day. This being so, to remain ignorant of the enemy’s situation simply because one begrudges spending a hundred ounces of silver on honors and salaries—

[“For spies” is of course the meaning, though actually mentioning spies here would spoil the effect of this elaborately built-up introduction.]

—is the height of inhumanity.

[Sūnzǐ’s argument is ingenious. He begins by pointing out the terrible suffering and enormous expense in blood and treasure that war always brings. Now, unless you are kept informed of the enemy’s condition and ready to strike at the right moment, a war may drag on for years. The only way to get this information is to employ spies, and you cannot get trustworthy spies unless you pay them properly. But it is surely false economy to begrudge a relatively trivial sum for this when every day the war continues consumes an immensely greater amount. This crushing burden falls on the poor, and so Sūnzǐ concludes that neglecting the use of spies is nothing less than a crime against humanity.]

3. One who acts this way is no leader of men, no real help to his sovereign, no master of victory.

[This idea—that the true aim of war is peace—is rooted in the Chinese national character. As far back as 597 B.C., Prince Chuang of the Ch’u State spoke these memorable words: “The [Chinese] character for ‘prowess’ is made up of [the characters for] ‘to stop’ and ‘a spear’ (cessation of hostilities). Military prowess shows itself in repressing cruelty, recalling weapons, preserving the appointment of Heaven, firmly establishing merit, bringing happiness to the people, creating harmony among the princes, and spreading wealth.”]

4. Therefore, what enables the wise sovereign and the able general to strike and conquer and accomplish things beyond ordinary reach is foreknowledge.

[That is, knowledge of the enemy’s positions and intentions.]

5. Now this foreknowledge cannot be drawn from spirits; it cannot be obtained inductively from experience,

[Tu Mu notes: “[Knowledge of the enemy] cannot be gained by reasoning from other analogous cases.”]

nor by any deductive calculation.

[Li Ch’uan says: “Quantities like length, width, distance, and size can be determined with exact mathematics; human actions cannot be calculated this way.”]

6. Knowledge of the enemy’s dispositions can only come from other people.

[Mei Yao-ch’en has an interesting note: “Knowledge of the spirit world is gained through divination; information in natural science may be sought through inductive reasoning; the laws of the universe can be verified by mathematical calculation; but the dispositions of an enemy can only be discovered through spies.”]

7. Hence the use of spies, of whom there are five kinds: (1) local spies; (2) inward spies; (3) converted spies; (4) doomed spies; (5) surviving spies.

8. When these five kinds of spy are all at work, no one can uncover the secret system. This is called “divine manipulation of the threads.” It is the sovereign’s most precious faculty.

[Cromwell, one of the greatest and most practical of all cavalry leaders, had officers called ‘scout masters,’ whose job was to gather every possible piece of information about the enemy through scouts and spies, and much of his success in war is traceable to the advance knowledge of the enemy’s moves so obtained. [1] ]

9. Having local spies means using the inhabitants of a district.

[Tu Mu says: “In the enemy’s country, win the people over by treating them well, and use them as spies.”]

10. Having inward spies means making use of officials of the enemy.

[Tu Mu lists the following types as likely to be useful: “Worthy men demoted from office, criminals who have been punished; also, favorite concubines greedy for gold, men resentful at being in subordinate positions or passed over for promotion, others who hope their own side will be defeated so they can display their abilities, and fickle turncoats who always want a foot in both camps. Officials of these kinds,” he continues, “should be quietly approached and tied to your interests with generous gifts. In this way you can find out conditions in the enemy’s country, learn the plans being made against you, and also stir discord between the sovereign and his ministers.” But extreme caution is needed with “inward spies,” as a historical incident related by Ho Shih shows: “Lo Shang, Governor of I-Chou, sent his general Wei Po to attack the rebel Li Hsiung of Shu in his stronghold at P’i. After each side had a number of victories and defeats, Li Hsiung made use of a man named P’o-t’ai, a native of Wu-tu. He had him whipped until he bled, then sent him to Lo Shang to trick him by offering to cooperate from inside the city and give a fire signal at the right moment for a general assault. Lo Shang, trusting these promises, marched out all his best troops, placing Wei Po and others at their head with orders to attack when P’o-t’ai signaled. Meanwhile, Li Hsiung’s general Li Hsiang had set an ambush along their route, and P’o-t’ai, after raising long scaling-ladders against the city walls, lit the beacon-fire. Wei Po’s men rushed at the signal and began climbing the ladders as fast as they could, while others were drawn up by ropes lowered from above. More than a hundred of Lo Shang’s soldiers entered the city this way, and every one of them was immediately beheaded. Li Hsiung then attacked with all his forces, both inside and outside the city, and completely routed the enemy.” [This happened in 303 A.D. I do not know where Ho Shih got the story, since it does not appear in the biography of Li Hsiung or his father Li T’e, Chin Shu, ch. 120, 121.]

11. Having converted spies means getting hold of the enemy’s spies and using them for our own purposes.

[By heavy bribes and generous promises, detaching them from the enemy’s service and inducing them to carry back false information as well as spying on their own countrymen. On the other hand, Hsiao Shih-hsien says we pretend not to have detected him, but contrive to let him take away a false impression of what is happening. Several commentators accept this as an alternative meaning, but it is not what Sūnzǐ meant, as proved conclusively by his later remarks about treating the converted spy generously (§ 21 ff.). Ho Shih notes three occasions when converted spies were used with conspicuous success: (1) by T’ien Tan in his defense of Chi-mo (see above, p. 90); (2) by Chao She on his march to O-yu (see p. 57); and (3) by the cunning Fan Chu in 260 B.C., when Lien P’o was conducting a defensive campaign against Ch’in. The King of Chao strongly disapproved of Lien P’o’s cautious and slow methods, which had failed to prevent a series of minor disasters, and so readily listened to the reports of his spies, who had secretly gone over to the enemy and were already in Fan Chu’s pay. They said: “The only thing Ch’in is worried about is the chance that Chao Kua might be made general. They consider Lien P’o an easy opponent, sure to be defeated in the long run.” Now Chao Kua was a son of the famous Chao She. From boyhood he had been wholly absorbed in the study of war, until he came to believe no commander in the whole Empire could stand against him. His father was greatly disturbed by this conceit and the flippant way he spoke of war, and solemnly declared that if Kua were ever made general, he would bring ruin on the armies of Chao. This was the man who, despite earnest protests from his own mother and the veteran statesman Lin Hsiang-ju, was now sent to replace Lien P’o. Needless to say, he was no match for the formidable Po Ch’i and the great military power of Ch’in. He fell into a trap that divided his army in two and cut his communications, and after a desperate resistance lasting 46 days, during which the starving soldiers ate each other, he was killed by an arrow, and his whole force—reportedly 400,000 men—was ruthlessly put to the sword.]

12. Having doomed spies means doing certain things openly as deception, and letting our own spies know about them so they report them to the enemy.

[Tu Yu gives the best explanation: “We ostentatiously do things designed to deceive our own spies, who must be led to believe they have unwittingly discovered the truth. Then, when these spies are captured in enemy lines, they make a completely false report, and the enemy acts on it, only to find that we do something quite different. The spies are then put to death.” As an example of doomed spies, Ho Shih mentions the prisoners released by Pan Ch’ao in his campaign against Yarkand. (See p. 132.) He also cites T’ang Chien, who in 630 A.D. was sent by T’ai Tsung to lull the Turkish Khan Chieh-li into a false sense of security until Li Ching could deliver a crushing blow. Chang Yu says the Turks took revenge by killing T’ang Chien, but this is a mistake, since we read in both the old and the New T’ang History (ch. 58, fol. 2 and ch. 89, fol. 8) that he escaped and lived until 656. Li I-chi played a somewhat similar part in 203 B.C., when sent by the King of Han to open peace negotiations with Ch’i. He has more claim to be called a “doomed spy,” for the king of Ch’i, attacked without warning by Han Hsin and enraged by what he saw as Li I-chi’s treachery, ordered the unfortunate envoy boiled alive.]

13. Finally, surviving spies are those who bring back news from the enemy’s camp.

[This is the ordinary kind of spy, properly speaking, forming a regular part of the army. Tu Mu says: “Your surviving spy must be a man of keen intellect though outwardly a fool; of shabby appearance but with an iron will. He must be active, robust, physically strong and brave, thoroughly used to all kinds of dirty work, able to endure hunger and cold, and to put up with shame and humiliation.” Ho Shih tells the following story of Ta-hsi Wu of the Sui dynasty: “When he was governor of Eastern Ch’in, Shen-wu of Ch’i made a hostile move on Sha-yuan. Emperor T’ai Tsu [? Kao Tsu] sent Ta-hsi Wu to spy on the enemy. He went with two other men. All three r