occupying the raised and sunny spots, and carefully guard your line of
supplies.
[The general meaning of the last phrase is doubtlessly, as Tu Yu says,
"not to allow the enemy to cut your communications." In view of
Napoleon’s dictum, "the secret of war lies in the communications," [1]
we could wish that Sun Tzŭ had done more than skirt the edge of this
important subject here and in I. § 10, VII. § 11. Col. Henderson says:
"The line of supply may be said to be as vital to the existence of an
army as the heart to the life of a human being. Just as the duelist who
finds his adversary’s point menacing him with certain death, and his
own guard astray, is compelled to conform to his adversary’s movements,
and to content himself with warding off his thrusts, so the commander
whose communications are suddenly threatened finds himself in a false
position, and he will be fortunate if he has not to change all his
plans, to split up his force into more or less isolated detachments,
and to fight with inferior numbers on ground which he has not had time
to prepare, and where defeat will not be an ordinary failure, but will
entail the ruin or surrender of his whole army." [2]
Then you will be able to fight with advantage.