備城門

Qin Guli asked Master Mozi: 'Following the words of the sages, the phoenix does not appear, the feudal lords have rebelled against the Shang-Zhou order, armored troops are rising everywhere under Heaven, the large attack the small and the strong seize the weak. I wish to defend a small state -- what should I do?' Master Mozi said: 'What type of attack would you defend against?' Qin Guli replied: 'The common methods of attack in today's world are: mounds for overlooking, hooks, battering rams, siege ladders, earthen ramps, water flooding, tunneling, breakthrough, hollow rams, ant-climbing, covered assault wagons, and elevated chariots. How does one defend against these twelve methods?'

Master Mozi said: 'When the city walls and moats are in good repair, defensive equipment is ready, grain supplies are sufficient, those above and below trust each other, and one can obtain relief from neighboring states -- these are the means of holding out.' The general method for defending a besieged city: the walls must be thick and high; the moats deep and wide; the towers and parapets in good repair with well-maintained defensive equipment; fuel and food sufficient for at least three months; a large and selected garrison; harmony between officials and people; senior ministers who have rendered service to the ruler, whose trustworthiness and righteousness attract the people's loyalty without limit. Failing that: the people's ancestral graves are there. Failing that: the surrounding forests and marshes provide ample resources. Failing that: the terrain is difficult to attack and easy to defend. Failing that: there is deep enmity against the enemy and great merit in the eyes of the ruler. Failing that: rewards are clearly trustworthy and punishments are severe enough to inspire fear. When these fourteen conditions are met, the city can be defended. When not a single one is met, even the most capable cannot defend it.

The general method for defending a city: to fortify the city gate, construct a suspended gate with a drop mechanism two zhang long and eight chi wide, made as a double-leaf gate; the gate leaves should overlap by three cun when closed. Earth is applied on top of the leaves, no more than two cun thick. A trench is dug in the center, one zhang five chi deep, as wide as the gate leaves, and of a length determined by the available labor.

The defensive standard: for every fifty paces of wall, assign ten adult men, twenty able-bodied women, and ten elderly and children -- a total of forty persons per fifty paces. For the garrison below the wall towers, the ratio is one person per pace: twenty people per twenty paces. Cities of all sizes should follow this ratio, which is sufficient for defense.