After that, comes tactical manœuvring, than which there is nothing
more difficult.
I have departed slightly from the traditional interpretation of
Ts‘ao Kung, who says: 從始受命至於交和軍爭難也 “From the time of
receiving the sovereign’s instructions until our encampment over
against the enemy, the tactics to be pursued are most difficult.”
It seems to me that the 軍爭 tactics or manœuvres can hardly be
said to begin until the army has sallied forth and encamped,
and Ch‘ên Hao’s note gives colour to this view: “For levying,
concentrating, harmonising and intrenching an army, there are
plenty of old rules which will serve. The real difficulty comes
when we engage in tactical operations.” Tu Yu also observes that
“the great difficulty is to be beforehand with the enemy in
seizing favourable positions.”
The difficulty of tactical manœuvring consists in turning the devious
into the direct, and misfortune into gain.
以迂爲直 is one of those highly condensed and somewhat enigmatical
expressions of which Sun Tzŭ is so fond. This is how it is
explained by Ts‘ao Kung: 示以遠速其道里先敵至也 “Make it appear that
you are a long way off, then cover the distance rapidly and arrive
on the scene before your opponent.” Tu Mu says: “Hoodwink the
enemy, so that he may be remiss and leisurely while you are
dashing along with the utmost speed.” Ho Shih gives a slightly
different turn to the sentence: “Although you may have difficult
ground to traverse and natural obstacles to encounter, this is a
drawback which can be turned into actual advantage by celerity of
movement.” Signal examples of this saying are afforded by the two
famous passages across the Alps—that of Hannibal, which laid Italy
at his mercy, and that of Napoleon two thousand years later, which
resulted in the great victory of Marengo.