9. The Army on the March
Literally, "no martial advance." That is to say, CHENG tactics and frontal attacks must be eschewed, and stratagem resorted to instead.
This is an obscure sentence, and none of the commentators succeed in squeezing very good sense out of it. I follow Li Ch`uan, who appears to offer the simplest explanation: "Only the side that gets more men will win." Fortunately we have Chang Yu to expound its meaning to us in language which is lucidity itself: "When the numbers are even, and no favorable opening presents itself, although we may not be strong enough to deliver a sustained attack, we can find additional recruits amongst our sutlers and camp-followers, and then, concentrating our forces and keeping a close watch on the enemy, contrive to snatch the victory. But we must avoid borrowing foreign soldiers to help us." He then quotes from Wei Liao Tzu, ch. 3: "The nominal strength of mercenary troops may be 100,000, but their real value will be not more than half that figure."