When an invading force crosses a river in its onward march, do not
advance to meet it in mid-stream. It will be best to let half the army
get across, and then deliver your attack.
The _T‘ung Tien_ and _Yü Lan_ read 度 for 濟, without change of
meaning. Wu Tzŭ plagiarises this passage twice over:—ch. II _ad
fin._, 涉水半渡可擊; ch. V, 敵若絶水半渡而擊. Li Ch‘üan alludes to
the great victory won by Han Hsin over 龍且 Lung Chü at the 濰 Wei
River. Turning to the _Ch‘ien Han Shu_, ch. 34, fol. 6 _verso_, we
find the battle described as follows: “The two armies were drawn
up on opposite sides of the river. In the night, Han Hsin ordered
his men to take some ten thousand sacks filled with sand and
construct a dam a little higher up. Then, leading half his army
across, he attacked Lung Chü; but after a time, pretending to have
failed in his attempt, he hastily withdrew to the other bank. Lung
Chü was much elated by this unlooked-for success, and exclaiming:
“I felt sure that Han Hsin was really a coward!” he pursued him
and began crossing the river in his turn. Han Hsin now sent a
party to cut open the sandbags, thus releasing a great volume of
water, which swept down and prevented the greater portion of Lung
Chü’s army from getting across. He then turned upon the force
which had been cut off, and annihilated it, Lung Chü himself being
amongst the slain. The rest of the army, on the further bank, also
scattered and fled in all directions.”