Romans were foolishly allowed to
fight fasting, whereas Hannibal's men had breakfasted at
their leisure. See Livy, XXI, liv. 8, lv. 1 and 8.]

by noonday it has begun to flag; and in the evening, his mind is
bent only on returning to camp.
29. A clever general, therefore, avoids an army when its
spirit is keen, but attacks it when it is sluggish and inclined
to return. This is the art of studying moods.
30. Disciplined and calm, to await the appearance of
disorder and hubbub amongst the enemy:--this is the art of
retaining self-possession.
31. To be near the goal while the enemy is still far from
it, to wait at ease while the enemy is toiling and struggling, to
be well-fed while the enemy is famished:--this is the art of
husbanding one's strength.
32. To refrain from intercepting an enemy whose banners are
in perfect order, to refrain from attacking an army drawn up in
calm and confident array:--this is the art of studying
circumstances.
33. It is a military axiom not to advance uphill against
the enemy, nor to oppose him when he comes downhill.
34. Do not pursue an enemy who simulates flight; do not
attack soldiers whose temper is keen.
35. Do not swallow bait offered by the enemy.

[Li Ch`uan and Tu Mu, with extraordinary inability to see a
metaphor, take these words quite literally of food and drink that
have been poisoned by the enemy. Ch`en Hao and Chang Yu
carefully point out that the saying has a wider application.]

Do not interfere with an army that is returning home.

[The commentators explain this rather singular piece of
advice by saying that a man whose heart is set on returning home
will fight to the death against any attempt to bar his way, and
is therefore too dangerous an opponent to be tackled. Chang Yu
quotes the words of Han Hsin: "Invincible is the soldier who
hath his desire and returneth homewards." A marvelous tale is
told of Ts`ao Ts`ao's courage and resource in ch. 1 of the SAN
KUO CHI: In 198 A.D., he was besieging Chang Hsiu in Jang, when
Liu Piao sent reinforcements with a view to cutting off Ts`ao's
retreat. The latter was obliged to draw off his troops, only to
find himself hemmed in between two enemies, who were guarding
each outlet of a narrow pass in which he had engaged himself. In
this desperate plight Ts`ao waited until nightfall, when he bored
a tunnel into the mountain side and laid an ambush in it