Chen Ji's Inquiry on Fortifications
无壁垒者，车为垒，弩为衡，步为守，骑为袭。
When there are no fortifications, use chariots as barriers, crossbows as defenses, infantry as guards, cavalry as raiders.
陈忌问垒曰：'吾闻兵法，必以坚壁，何以？'孙膑曰：'非坚壁也，必以车、弩、步、骑协同，险地设伏，以逸待劳。'
无壁垒者，车为垒，弩为衡，步为守，骑为袭，控隘道，断归路。
陈忌问关于防御工事的问题："我听说兵法上说必须依靠坚固的壁垒，为什么？"孙膑回答："不只是坚固的壁垒，而是要以战车、弩兵、步兵、骑兵协同作战，在险要之地设伏，以逸待劳。"没有现成壁垒时，用战车作屏障，弩兵作防线，步兵守卫，骑兵突击，控制隘道，切断退路。
Chen Ji asked about fortifications. Sun Bin replied: "Not just strong fortifications, but coordination of chariots, crossbows, infantry, and cavalry, ambushes in dangerous areas, and waiting for the enemy while resting." When there are no fortifications, use chariots as barriers, crossbows as defenses, infantry as guards, cavalry as raiders, occupy narrow passes, and cut off the enemy's retreat.
无壁垒时，以车弩步骑协同布阵；险地设伏、以逸待劳
Coordinate chariots, crossbows, infantry, cavalry; ambush in dangerous terrain.
孙膑的"动态防御"思想——不依赖固定工事，而是以兵种协同创造移动防线。这是对静态防御的重大突破，体现了"以战代守"的积极防御理念。
Compare to mobile defense doctrine (German Bewegliche Verteidigung). Compare to modern combined arms operations.
韩信背水列阵激发士气，同时派骑兵突袭赵军营垒，前后夹击大败赵军。
Han Xin lined up with his back to the river to inspire his troops' fighting spirit, while sending cavalry to raid the Zhao camp, crushing them in a pincer attack.
斯巴达国王列奥尼达利用温泉关隘道地形，以少量精兵阻击波斯大军。
King Leonidas of Sparta used the narrow pass at Thermopylae to hold off the massive Persian army with a small elite force.
阿富汗游击队利用山地地形，以灵活机动战术对抗装备精良的苏军。
Afghan guerrillas used mountainous terrain and flexible mobile tactics to fight the well-equipped Soviet army.