This passage lays out camping and combat rules for four terrains: mountains, rivers, marshes and plains. It details optimal positions and tactics like striking foes halfway across water. Mastery of such geographic edges enabled the Yellow Emperor to defeat rival tribal lords.
This passage warns against reckless forced marches: rushing ahead loses supplies, while full baggage slows troops. Longer rapid marches cause severe troop attrition. It stresses armies need supplies, plus knowing allies, terrain and guides for safe movement.