Weak Points & Strong/Illusion and Reality explains how an army's opportunities come from the openings in the environment caused by the relative weakness of the enemy in a given area.
Learning highlight : <<故善战者，致人而不致于人>> ~ The person adept in warfare seeks to control and manipulate his enemy instead of being controlled and manipulated.
Cache is attached to a tall structure and near to ground level.
Bonus' data to collect : what is the "red number" on the structure? Take this as C6.
Bonus cache : GC49EWB (The Art of War Bonus - Left Flank).