Book 14 · 备水 · Chapter 46
城内堑外周道，广八步，备水谨度四旁高下。城地中偏下，令耳亓内，及下地，地深穿之令漏泉。置则瓦井中，视外水深丈以上，凿城内水耳。
Within the city wall dig a moat, and outside it a circular road eight paces wide. In preparing against inundation, carefully survey the relative heights of the ground on all four sides. Where the ground inside the city is low-lying, set drainage conduits there, and at the lowest ground dig deep so as to let the water flow off into springs. Set earthenware pipes within wells. When you observe that the water outside has risen to a depth of one zhang or more, bore drainage conduits to carry off the water inside the city.
并船以为十临，临三十人，人擅弩计四有方，必善以船为轒轀。二十船为一队，选材士有力者三十人共船，亓二十人人擅有方，剑甲鞮瞀，十人人擅苗。先养材士为异舍，食亓父母妻子以为质，视水可决，以临轒轀，决外堤，城上为射机疾佐之。
Lash boats together to make ten assault-rafts (lin); each raft carries thirty men. Each man is armed with a crossbow, and four of them carry the "fang" (a polearm or boarding-weapon). They must be skilled, using the boats as covered assault-vehicles (fen-wen). Twenty boats make one squad. Select strong and able-bodied men, thirty to a boat; of these, twenty men each carry a "fang," together with sword, armor, leather boots, and helmet, while ten men each carry a long lance (miao). Beforehand, lodge these picked soldiers in separate quarters, feed their fathers, mothers, wives, and children as hostages [for their loyalty]. When you judge that the [enemy's] water can be breached, use the assault-rafts and covered vehicles to break open the outer dyke, while atop the wall the shooting-engines are worked vigorously in their support.