Having _inward spies_, making use of officials of the enemy.
官 includes both civil and military officials. 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
(飜覆變詐常持兩端之心者). 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: “羅尙 Lo Shang, Governor of 益州 I-chou, sent his
general 隗伯 Wei Po to attack the rebel 李雄 Li Hsiung of 蜀 Shu in
his stronghold at 郫 P‘i. After each side had experienced a number
of victories and defeats, Li Hsiung had recourse to the services
of a certain 朴泰 P‘o-t‘ai, a native of 武都 Wu-tu. He began by
having him whipped until the blood came, and then sent him off to
Lo Shang, whom he was to delude by offering to co-operate 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, marched 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, 李驤 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 特 T‘ê, _Chin Shu_, ch. 120, 121.]