When you leave your own country behind, and take your army across neighborhood territory, 641 you find yourself on critical ground. 642 When there are means of communication 643 on all four sides, the ground is one of intersecting highways. 644

When you penetrate deeply into a country, it is serious ground. When you penetrate but a little way, it is facile ground.

When you have the enemy’s strongholds on your rear, 645 and narrow passes in front, it is hemmed-in ground. When there is no place of refuge at all, it is desperate ground.