Chapter XIII — THE USE OF SPIES

1. Sun Tzŭ said: Raising a host of a hundred thousand men and marching them
great distances entails heavy loss on the people and a drain on the resources
of the State. The daily expenditure will amount to a thousand ounces of silver.

[Cf. II. §§ 1, 13, 14.]

There will be commotion at home and abroad, and men will drop down exhausted on
the highways.

[Cf. Tao Te Ching, ch. 30: “Where troops have been quartered, brambles and
thorns spring up. Chang Yu has the note: “We may be reminded of the saying: ‘On
serious ground, gather in plunder.’ Why then should carriage and transportation
cause exhaustion on the highways?—The answer is, that not victuals alone,
but all sorts of munitions of war have to be conveyed to the army. Besides, the
injunction to ‘forage on the enemy’ only means that when an army is deeply
engaged in hostile territory, scarcity of food must be provided against. Hence,
without being solely dependent on the enemy for corn, we must forage in order
that there may be an uninterrupted flow of supplies. Then, again, there are
places like salt deserts where provisions being unobtainable, supplies from
home cannot be dispensed with.”]

As many as seven hundred thousand families will be impeded in their labor.

[Mei Yao-ch’en says: “Men will be lacking at the plough-tail.” The
allusion is to the system of dividing land into nine parts, each consisting of
about 15 acres, the plot in the center being cultivated on behalf of the State
by the tenants of the other eight. It was here also, so Tu Mu tells us, that
their cottages were built and a well sunk, to be used by all in common. [See
II. § 12, note.] In time of war, one of the families had to serve in the army,
while the other seven contributed to its support. Thus, by a levy of 100,000
men (reckoning one able-bodied soldier to each family) the husbandry of 700,000
families would be affected.]

2. Hostile armies may face each other for years, striving for the victory which
is decided in a single day. This being so, to remain in ignorance of the
enemy’s condition simply because one grudges the outlay of a hundred ounces of
silver in honours and emoluments,

[“For spies” is of course the meaning, though it would spoil the effect of this
curiously elaborate exordium if spies were actually mentioned at this point.]

is the height of inhumanity.

[Sun Tzŭ’s agreement is certainly ingenious. He begins by adverting to the
frightful misery and vast expenditure of blood and treasure which war always
brings in its train. Now, unless you are kept informed of the enemy’s
condition, and are 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 it is
impossible to obtain trustworthy spies unless they are properly paid for their
services. But it is surely false economy to grudge a comparatively trifling
amount for this purpose, when every day that the war lasts eats up an
incalculably greater sum. This grievous burden falls on the shoulders of the
poor, and hence Sun Tzŭ concludes that to neglect the use of spies is nothing
less than a crime against humanity.]

3. One who acts thus is no leader of men, no present help to his sovereign, no
master of victory.

[This idea, that the true object of war is peace, has its root in the national
temperament of the Chinese. Even so far back as 597 B.C., these memorable words
were uttered by Prince Chuang of the Ch’u State: “The [Chinese] character
for ‘prowess’ is made up of [the characters for] ‘to stay’ and ‘a spear’
(cessation of hostilities). Military prowess is seen in the repression of
cruelty, the calling in of weapons, the preservation of the appointment of
Heaven, the firm establishment of merit, the bestowal of happiness on the
people, putting harmony between the princes, the diffusion of wealth.”]

4. Thus, what enables the wise sovereign and the good general to strike and
conquer, and achieve things beyond the reach of ordinary men, is foreknowledge.

[That is, knowledge of the enemy’s dispositions, and what he means to do.]

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

[Tu Mu’s note is: “[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, breadth, distance and
magnitude, are susceptible of exact mathematical determination; human actions
cannot be so calculated.”]

6. Knowledge of the enemy’s dispositions can only be obtained from other men.

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

7. Hence the use of spies, of whom there are five classes: (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, none can discover 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 styled ‘scout masters,’ whose business it was to collect all possible
information regarding the enemy, through scouts and spies, etc., and much of
his success in war was traceable to the previous knowledge of the enemy’s moves
thus gained.” [1] ]

9. Having local spies means employing the services of the inhabitants of a
district.

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

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

[Tu Mu enumerates the following classes as likely to do good service in this
respect: “Worthy men who have been degraded from office, criminals who have
undergone punishment; also, favourite concubines who are greedy for gold, men
who are aggrieved at being in subordinate positions, or who have been passed
over in the distribution of posts, others who are anxious that their side
should be defeated in order that they may have a chance of displaying their
ability and talents, fickle turncoats who always want to have a foot in each
boat. Officials of these several kinds,” he continues, “should be secretly
approached and bound to one’s interests by means of rich presents. In this way
you will be able to find out the state of affairs in the enemy’s country,
ascertain the plans that are being formed against you, and moreover disturb the
harmony and create a breach between the sovereign and his ministers.” The
necessity for extreme caution, however, in dealing with “inward spies,” appears
from an historical incident related by Ho Shih: “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 experienced a number of victories and
defeats, Li Hsiung had recourse to the services of a certain
P’o-t’ai, a native of Wu-tu. He began to have him whipped until the
blood came, and then sent him off to Lo Shang, whom he was to delude by
offering to cooperate with him from inside the city, and to give a fire signal
at the right moment for making a general assault. Lo Shang, confiding in these
promises, march out all his best troops, and placed Wei Po and others at their
head with orders to attack at P’o-t’ai’s bidding. Meanwhile, Li
Hsiung’s general, Li Hsiang, had prepared an ambuscade on their line of march;
and P’o-t’ai, having reared long scaling-ladders against the city
walls, now lighted the beacon-fire. Wei Po’s men raced up on seeing 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 in this way, every one of whom was forthwith beheaded. Li
Hsiung then charged with all his forces, both inside and outside the city, and
routed the enemy completely.” [This happened in 303 A.D. I do not know where Ho
Shih got the story from. It is not given in the biography of Li Hsiung or that
of his father Li T’e, Chin Shu, ch. 120, 121.]

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

[By means of heavy bribes and liberal promises detaching them from the enemy’s
service, and inducing them to carry back false information as well as to spy in
turn on their own countrymen. On the other hand, Hsiao Shih-hsien says that we
pretend not to have detected him, but contrive to let him carry away a false
impression of what is going on. Several of the commentators accept this as an
alternative definition; but that it is not what Sun Tzŭ meant is conclusively
proved by his subsequent remarks about treating the converted spy generously (§
21 sqq.). Ho Shih notes three occasions on which converted spies were used with
conspicuous success: (1) by T’ien Tan in his defence of Chi-mo (see
supra, p. 90); (2) by Chao She on his march to O-yu (see p. 57); and by the
wily 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 dilatory methods, which had been unable to avert a
series of minor disasters, and therefore lent a ready ear 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 which causes Ch’in anxiety is lest Chao
Kua should be made general. Lien P’o they consider an easy opponent, who
is sure to be vanquished in the long run.” Now this Chao Kua was a son of the
famous Chao She. From his boyhood, he had been wholly engrossed in the study of
war and military matters, until at last he came to believe that there was no
commander in the whole Empire who could stand against him. His father was much
disquieted by this overweening conceit, and the flippancy with which he spoke
of such a serious thing as war, and solemnly declared that if ever Kua was
appointed general, he would bring ruin on the armies of Chao. This was the man
who, in spite of earnest protests from his own mother and the veteran statesman
Lin Hsiang-ju, was now sent to succeed Lien P’o. Needless to say, he
proved no match for the redoubtable Po Ch’i and the great military power
of Ch’in. He fell into a trap by which his army was divided into two and
his communications cut; and after a desperate resistance lasting 46 days,
during which the famished soldiers devoured one another, he was himself killed
by an arrow, and his whole force, amounting, it is said, to 400,000 men,
ruthlessly put to the sword.]

12. Having doomed spies, doing certain things openly for purposes of
deception, and allowing our own spies to know of them and report them to the
enemy.

[Tu Yu gives the best exposition of the meaning: “We ostentatiously do things
calculated to deceive our own spies, who must be led to believe that they have
been unwittingly disclosed. Then, when these spies are captured in the enemy’s
lines, they will make an entirely false report, and the enemy will take
measures accordingly, only to find that we do something quite different. The
spies will thereupon be 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 refers to T’ang Chien, who in 630 A.D. was
sent by T’ai Tsung to lull the Turkish Kahn Chieh-li into fancied
security, until Li Ching was able to deliver a crushing blow against him. Chang
Yu says that the Turks revenged themselves by killing T’ang Chien, but
this is a mistake, for we read in both the old and the New T’ang History
(ch. 58, fol. 2 and ch. 89, fol. 8 respectively) that he escaped and lived on
until 656. Li I-chi played a somewhat similar part in 203 B.C., when sent by
the King of Han to open peaceful negotiations with Ch’i. He has certainly
more claim to be described a “doomed spy”, for the king of Ch’i, being
subsequently attacked without warning by Han Hsin, and infuriated by what he
considered the treachery of Li I-chi, ordered the unfortunate envoy to be
boiled alive.]

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

[This is the ordinary class of spies, properly so called, forming a regular
part of the army. Tu Mu says: “Your surviving spy must be a man of keen
intellect, though in outward appearance a fool; of shabby exterior, but with a
will of iron. He must be active, robust, endowed with physical strength and
courage; thoroughly accustomed to all sorts of dirty work, able to endure
hunger and cold, and to put up with shame and ignominy.” 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 movement upon
Sha-yuan. The Emperor T’ai Tsu [? Kao Tsu] sent Ta-hsi Wu to spy upon the
enemy. He was accompanied by two other men. All three were on horseback and
wore the enemy’s uniform. When it was dark, they dismounted a few hundred feet
away from the enemy’s camp and stealthily crept up to listen, until they
succeeded in catching the passwords used in the army. Then they got on their
horses again and boldly passed through the camp under the guise of
night-watchmen; and more than once, happening to come across a soldier who was
committing some breach of discipline, they actually stopped to give the culprit
a sound cudgeling! Thus they managed to return with the fullest possible
information about the enemy’s dispositions, and received warm commendation from
the Emperor, who in consequence of their report was able to inflict a severe
defeat on his adversary.”]

14. Hence it is that with none in the whole army are more intimate relations
to be maintained than with spies.

[Tu Mu and Mei Yao-ch’en point out that the spy is privileged to enter
even the general’s private sleeping-tent.]

None should be more liberally rewarded. In no other business should greater
secrecy be preserved.

[Tu Mu gives a graphic touch: all communication with spies should be carried
“mouth-to-ear.” The following remarks on spies may be quoted from Turenne, who
made perhaps larger use of them than any previous commander: “Spies are
attached to those who give them most, he who pays them ill is never served.
They should never be known to anybody; nor should they know one another. When
they propose anything very material, secure their persons, or have in your
possession their wives and children as hostages for their fidelity. Never
communicate anything to them but what is absolutely necessary that they should
know. [2] ]

15. Spies cannot be usefully employed without a certain intuitive sagacity.

[Mei Yao-ch’en says: “In order to use them, one must know fact from
falsehood, and be able to discriminate between honesty and double-dealing.”
Wang Hsi in a different interpretation thinks more along the lines of
“intuitive perception” and “practical intelligence.” Tu Mu strangely refers
these attributes to the spies themselves: “Before using spies we must assure
ourselves as to their integrity of character and the extent of their experience
and skill.” But he continues: “A brazen face and a crafty disposition are more
dangerous than mountains or rivers; it takes a man of genius to penetrate
such.” So that we are left in some doubt as to his real opinion on the
passage.”]

16. They cannot be properly managed without benevolence and
straightforwardness.

[Chang Yu says: “When you have attracted them by substantial offers, you must
treat them with absolute sincerity; then they will work for you with all their
might.”]

17. Without subtle ingenuity of mind, one cannot make certain of the truth of
their reports.

[Mei Yao-ch’en says: “Be on your guard against the possibility of spies
going over to the service of the enemy.”]

18. Be subtle! be subtle! and use your spies for every kind of business.

[Cf. VI. § 9.]

19. If a secret piece of news is divulged by a spy before the time is ripe, he
must be put to death together with the man to whom the secret was told.

[Word for word, the translation here is: “If spy matters are heard before [our
plans] are carried out,” etc. Sun Tzŭ’s main point in this passage is: Whereas
you kill the spy himself “as a punishment for letting out the secret,” the
object of killing the other man is only, as Ch’en Hao puts it, “to stop
his mouth” and prevent news leaking any further. If it had already been
repeated to others, this object would not be gained. Either way, Sun Tzŭ lays
himself open to the charge of inhumanity, though Tu Mu tries to defend him by
saying that the man deserves to be put to death, for the spy would certainly
not have told the secret unless the other had been at pains to worm it out of
him.”]

20. Whether the object be to crush an army, to storm a city, or to assassinate
an individual, it is always necessary to begin by finding out the names of the
attendants, the aides-de- camp,

[Literally “visitors”, is equivalent, as Tu Yu says, to “those whose duty it is
to keep the general supplied with information,” which naturally necessitates
frequent interviews with him.]

the door-keepers and sentries of the general in command. Our spies must be
commissioned to ascertain these.

[As the first step, no doubt towards finding out if any of these important
functionaries can be won over by bribery.]

21. The enemy’s spies who have come to spy on us must be sought out, tempted
with bribes, led away and comfortably housed. Thus they will become converted
spies and available for our service.

22. It is through the information brought by the converted spy that we are able
to acquire and employ local and inward spies.

[Tu Yu says: “through conversion of the enemy’s spies we learn the enemy’s
condition.” And Chang Yu says: “We must tempt the converted spy into our
service, because it is he that knows which of the local inhabitants are greedy
of gain, and which of the officials are open to corruption.”]

23. It is owing to his information, again, that we can cause the doomed spy to
carry false tidings to the enemy.

[Chang Yu says, “because the converted spy knows how the enemy can best be
deceived.”]

24. Lastly, it is by his information that the surviving spy can be used on
appointed occasions.

25. The end and aim of spying in all its five varieties is knowledge of the
enemy; and this knowledge can only be derived, in the first instance, from the
converted spy.

[As explained in §§ 22-24. He not only brings information himself, but makes it
possible to use the other kinds of spy to advantage.]

Hence it is essential that the converted spy be treated with the utmost
liberality.

26. Of old, the rise of the Yin dynasty

[Sun Tzŭ means the Shang dynasty, founded in 1766 B.C. Its name was changed to
Yin by P’an Keng in 1401.

was due to I Chih

[Better known as I Yin, the famous general and statesman who took part in
Ch’eng T’ang’s campaign against Chieh Kuei.]

who had served under the Hsia. Likewise, the rise of the Chou dynasty was due
to Lü Ya

[Lu Shang rose to high office under the tyrant Chou Hsin, whom he afterwards
helped to overthrow. Popularly known as T’ai Kung, a title bestowed on
him by Wen Wang, he is said to have composed a treatise on war, erroneously
identified with the Liu T’ao.]

who had served under the Yin.

[There is less precision in the Chinese than I have thought it well to
introduce into my translation, and the commentaries on the passage are by no
means explicit. But, having regard to the context, we can hardly doubt that Sun
Tzŭ is holding up I Chih and Lu Ya as illustrious examples of the converted
spy, or something closely analogous. His suggestion is, that the Hsia and Yin
dynasties were upset owing to the intimate knowledge of their weaknesses and
shortcoming which these former ministers were able to impart to the other side.
Mei Yao-ch’en appears to resent any such aspersion on these historic
names: “I Yin and Lu Ya,” he says, “were not rebels against the Government.
Hsia could not employ the former, hence Yin employed him. Yin could not employ
the latter, hence Hou employed him. Their great achievements were all for the
good of the people.” Ho Shih is also indignant: “How should two divinely
inspired men such as I and Lu have acted as common spies? Sun Tzŭ’s mention of
them simply means that the proper use of the five classes of spies is a matter
which requires men of the highest mental caliber like I and Lu, whose wisdom
and capacity qualified them for the task. The above words only emphasize this
point.” Ho Shih believes then that the two heroes are mentioned on account of
their supposed skill in the use of spies. But this is very weak.]

27. Hence it is only the enlightened ruler and the wise general who will use
the highest intelligence of the army for purposes of spying and thereby they
achieve great results.

[Tu Mu closes with a note of warning: “Just as water, which carries a boat from
bank to bank, may also be the means of sinking it, so reliance on spies, while
production of great results, is oft-times the cause of utter destruction.”]

Spies are a most important element in war, because on them depends an army’s
ability to move.

[Chia Lin says that an army without spies is like a man without ears or eyes.]

[1] “Aids to Scouting,” p. 2.

[2] “Marshal Turenne,” p. 311.