With regard to _precipitous heights_, if you are beforehand with your
adversary, you should occupy the raised and sunny spots, and there
wait for him to come up.
Ts‘ao Kung says: 地形險隘尤不可致於人 “The particular advantage of
securing heights and defiles is that your actions cannot then
be dictated by the enemy.” [For the enunciation of the grand
principle alluded to, see VI. § 2]. Chang Yü tells the following
anecdote of 裴行儉 P‘ei Hsing-chien (A.D. 619–682), who was sent
on a punitive expedition against the Turkic tribes. “At nightfall
he pitched his camp as usual, and it had already been completely
fortified by wall and ditch, when suddenly he gave orders that the
army should shift its quarters to a hill near by. This was highly
displeasing to his officers, who protested loudly against the
extra fatigue which it would entail on the men. P‘ei Hsing-chien,
however, paid no heed to their remonstrances and had the camp
moved as quickly as possible. The same night, a terrific storm
came on, which flooded their former place of encampment to the
depth of over twelve feet. The recalcitrant officers were amazed
at the sight, and owned that they had been in the wrong. ‘How did
you know what was going to happen?’ they asked. P‘ei Hsing-chien
replied: ‘From this time forward be content to obey orders without
asking unnecessary questions.’ [See _Chiu T‘ang Shu_, ch. 84, fol.
12 _r_^o, and _Hsin T‘ang Shu_, ch. 108, fol. 5 _v_^o.] From this
it may be seen,” Chang Yü continues, “that high and sunny places
are advantageous not only for fighting, but also because they are
immune from disastrous floods.”