[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. As soon as the
whole army had passed by, the hidden troops fell on his rear, while
Ts’ao himself turned and met his pursuers in front, so that they were
thrown into confusion and annihilated. Ts’ao Ts’ao said afterwards:
"The brigands tried to check my army in its retreat and brought me to
battle in a desperate position: hence I knew how to overcome them."]