This passage from The Art of War emphasizes proactive defense. Never hope the enemy will stay away or refrain from attacking; instead, fully prepare your troops and fortify positions to make your camp unassailable against any incoming assaults.
Sun Tzu states hiding your battlefield forces foes to spread defenses thin everywhere. Troops weaken when passively guarding all fronts. Wu Zixu’s rotating border raids on Chu perfectly embody this logic, exhausting Chu’s scattered army and paving Wu’s final victory.