We cannot enter into alliance with neighbouring princes until we are
acquainted with their designs. We are not fit to lead an army on
the march unless we are familiar with the face of the country—its
mountains and forests, its pitfalls and precipices, its marshes and
swamps. We shall be unable to turn natural advantages to account
unless we make use of local guides.
These three sentences are repeated from VII. §§ 12–14—in order
to emphasise their importance, the commentators seem to think. I
prefer to regard them as interpolated here in order to form an
antecedent to the following words. With regard to local guides,
Sun Tzŭ might have added that there is always the risk of going
wrong, either through their treachery or some misunderstanding
such as Livy records (XXII. 13): Hannibal, we are told, ordered a
guide to lead him into the neighbourhood of Casinum, where there
was an important pass to be occupied; but his Carthaginian accent,
unsuited to the pronunciation of Latin names, caused the guide to
understand Casilinum instead of Casinum, and turning from his
proper route, he took the army in that direction, the mistake not
being discovered until they had almost arrived.