If forced to fight in a salt-marsh, you should have water and grass near you, and get your back to a clump of trees. 443 So much for operations in salt-marshes.

In dry, level country, take up an easily accessible position 444 with rising ground to your right and on your rear, 445 so that the danger may be in front, and safety lie behind. 446 So much for campaigning in flat country.

These are the four useful branches of military knowledge 447 which enabled the Yellow Emperor to vanquish four several sovereigns. 448