Chapter 52: Preparation of City Gates
Qin Guli asked Master Mo Zi: “According to the words of the sages, the phoenix no longer appears. The feudal lords have betrayed the order inherited from Yin and Zhou, and warfare is rising throughout the world. The large states attack the small, and the strong seize the weak. I wish to devise methods for defending small states – what should be done?”
Mo Zi said: “What kind of attack are you preparing to defend against?”
Qin Guli replied: “The methods commonly used for attacking cities today are: siege towers (lin), grappling hooks (gou), battering rams (chong), scaling ladders (ti), earthen ramps (yin), water attacks (shui), tunneling (xue), sudden sorties (tu), hollow breaches (kongdong), swarming assaults like ants (yifu), covered wagons (fenwen), and assault chariots (xuanche). May I ask how to defend against these twelve?”
Mo Zi said: “If our city walls are repaired and high, our moats deep and wide, our defensive equipment complete, our firewood and grain sufficient, our superiors and subordinates devoted to one another, and we can obtain aid from neighboring lords – these are the means by which we can hold out. Moreover, even if the defender is skilled, he still cannot defend if the ruler does not employ him. And if the ruler employs a defender who is not capable, he still cannot defend. Therefore, the defender must be skilled AND the ruler must honor and employ him – only then can the city be defended.”
The general principles for defending a besieged city are: walls thick and high; moats deep and wide; watchtowers sturdy; defensive equipment well-maintained; firewood and provisions sufficient to last three months or more; personnel selected with care; officials and people in harmony; many ministers who have rendered meritorious service; the ruler trustworthy and righteous, so that the people rejoice endlessly. Failing that: the people’s parents and ancestral tombs are within the city; failing that: the mountains, forests, marshes, and grasslands provide abundant profit; failing that: the terrain is difficult to attack and easy to defend; failing that: the people bear deep resentment toward the enemy and have great merit with their ruler; failing that: rewards are clear and trustworthy, and punishments are severe and feared. When these fourteen conditions are all present, the people will not turn against their superiors, and only then can the city be defended. If even one of the fourteen is lacking, then even a skilled defender cannot hold the city.
Therefore, the general principles for defending a city are as follows: For the city gates, install a suspended gate (xuanmen). The lifting mechanism (chenji) should be two zhang long and eight chi wide, with two matching parts. The gate panels should fit together with gaps of no more than three cun. Apply no more than two cun of earth on top of the panels. Dig a trench in front of the gate, one zhang and five chi deep, as wide as the gate panels, and of a length proportionate to the force required. At the end of the trench, install a suspended platform that can hold one person.
When the enemy arrives, order all gates and doors to be drilled with holes and fitted with rings. Each should have two rings and two holes, one drilled and fitted with a rope four chi long. At all four sides and four corners of the city, build high watchtowers and station the sons of noble families upon them to observe the enemy – watching their formations, movements, and shifts to the left and right. Any sentry who fails in this duty shall be executed.
If the enemy tunnels toward us, immediately dispatch tunneling experts (xueshi) to select the best men and dig counter-tunnels to meet them, and install crossbow mechanisms inside to respond.
All wooden beams, tiles, and stones in the people’s houses that can be used for city defense must be turned over to the authorities. Those who disobey this order shall be executed.
For the fortifications: place one barricade every seven chi, one rampart every five paces. For every five barricades, provide a spade. Long-handled axes should have shafts eight chi long. Every ten paces, provide a long sickle with an eight-chi handle. Every ten paces, provide a long mace (changzhui) with a six-chi handle and a one-chi head, with axe-blades at both ends. Every three paces, place a large iron spike (dating), with a one-chi front and five-cun claws. Cross two spikes and set them level – if not level, they are ineffective. Sharpen both ends.
For tunneling teams and battering-ram teams, carefully assess the width of the attacking formation, then dig diagonal tunnels so that the width of your opening matches the width of the enemy’s assault column.
Bundle trees loosely to make fire-logs (chaituan). For the outer face, use logs one zhang and seven chi and one cun long. Lay the fire-logs crosswise on the outside, then coat the exterior with thick mud so that no earth shows through. Make the width and thickness sufficient to support a wall of three zhang and five chi or higher. Gradually fill in with brushwood and earth to block it, making it as urgent and solid as possible. Prepare the front-face timbers in advance and join them early, so they can bear the mud coating and serve as battlements. Coat the exterior thoroughly so that it cannot be burned or pulled apart.
For a large city, build a postern gate (guimen) one zhang and five chi wide, four chi across. Build an outer gate (guomen) outside the main gate. Place a crossbeam between two wooden posts at the gate, drill holes in the posts, and secure them to the battlements above. Install a cutting suspended beam to sever the city approach. Use angled plank bridges leading outward, laid in sequence, sloping inward like the city wall’s batter. Inside the city, build earthen ramparts and use the inner earth as the outer defense. Dig trenches between them, one zhang and five chi deep. Fill the chambers with firewood, which can be set ablaze when the enemy approaches.
Attach listening-posts (ling’er) to the city wall and build double-layered towers. Dig beneath the outer battlements to a depth of one zhang and five chi and a width of one zhang and two chi. In the towers and listening-posts, assign the strongest men to face the enemy and the best archers to fire, with all assistants fully supplied with arrows. Construct rotating crossbow platforms (zhuansheji): the mechanism is six chi long with one chi buried. Join two timbers to form the carriage (wen), two chi long. In the center, drill a channel for the firing arm, with the arm reaching to the pivot. Place one every twenty paces, with a skilled archer as assistant, and let no one leave his post.
Every hundred paces on the wall, build a tower with four posts, each post fitted with a through-beam. The lower level is one zhang high, the upper level nine chi, with width and length each one zhang and six chi, all roofed. Every thirty paces, build a projecting emplacement (tu) nine chi long, ten chi wide, and eight chi high, with an opening three chi wide and a marker two chi high, all roofed. On the wall, install fire-brand holders (cuanhuo) with poles whose length matches the height of the wall, and place fire at their tips. Every nine chi on the wall, position one crossbow, one halberd, one mace, one axe, and one sickle, with piles of stones and caltrops beside them.
Build defensive barriers (qu) six chi long with twelve-chi arms and six-chi posts, with three chi buried. Set the barriers five cun from the battlements. Construct fire-screens (jimo) eight chi long and seven chi wide, with five-chi-wide wooden frames and a central bridge of bundled straw, with ropes at the ends. When the enemy attacks, one man goes up and down the screen without leaving. Every twenty paces on the wall, place a catapult (jiche); where the main assault comes, do not limit yourself to this number.
Every thirty paces on the wall, build a stove. Those carrying water must use cloth or leather buckets and leather basins, placed every ten paces. The handles should be eight chi long, and the buckets should hold two to three dou. Every ten paces, provide old and new cloth six chi long, with crude handles one zhang long. Every ten paces, place a hook (qian). Use water jars holding three shi or more, mixing large and small. Provide two basins and two ladles each. Prepare dried rations for the troops: two dou per person, stored in dry places in case of rain. Order the defenders to distribute meals outside the battlements.
Prepare equipment by crushing sand, gravel, and iron into broken-jar projectiles. Have the potters make thin-walled jars holding one to two dou, for immediate use, bound in sets of three. Build sturdy dividing walls on the rampart. Construct walkways twelve chi high with one sharpened end. Build postern gates with two panels, each capable of closing independently.
For defending against earthen siege ramps (yinchi): use fire and contest the approach, operating bellows. Pack clay on the inner and outer sides, and use brushwood as fuel. Set fire-pins (lingding) every three zhang, with fire-ears attached. Station one man every ten paces inside brushwood with a crossbow; for half the crossbows, surround them with dog-spear rings. Build walls every seven paces.
For defending against fire-attack chariots: when flaming arrows are shot at the city gates, drill holes in the gate panels and install walkways, then coat them with mud. Use cloth buckets and leather basins to fight the fire. The gate panels should have thin posts, each drilled half a chi deep, with one-inch pegs every seven cun, coated thickly with mud as fire protection. At each gate, place a water-dropping device with jars holding three shi or more, mixing large and small.
Gate posts and bolts must be secured with iron bands or iron plates, made absolutely firm. Double the gate bolts and plate them with iron for strength. Seal the bolts with a guard-seal, and have inspectors regularly check the seals and the depth of bolt insertion. Gate guards must not carry axes, adzes, chisels, saws, or maces.
Every two paces on the wall, place a barrier post one zhang and three chi tall, with a ten-zhang crown and a six-chi shield. Every two paces, place a screen nine chi wide and twelve chi long. Every two paces, position one flail, one long axe, and one long mace; place twenty spears within the two-pace interval. Every two paces, install a wooden crossbow capable of shooting at least fifty paces. Make many arrows – not only bamboo arrows, but also arrows of hardwood, zhao-wood, and elm. Seek iron from Qi for making projectiles to shoot at battering rams and siege towers.
Every two paces, pile stones weighing a thousand jun or more – five hundred of them. If fewer than a hundred, use quicklime, wall-stones, or any suitable material. Every two paces, pile twenty large logs, one circumference thick and one zhang long. Every five paces, place a jar of water, with small ladles holding one dou each. Every five paces, pile five hundred dog-spear stakes, each three chi long, with bundled ends and firm pegs. Every ten paces, pile twenty large logs over two circumferences thick and eight chi long.
Every twenty-five paces, build a stove with an iron cauldron holding one shi or more, kept filled with boiling water. Also keep no less than a thousand shi of sand. Every thirty paces, build a seated observation tower projecting four chi beyond the battlements, three chi wide and four chi long, with boards on three sides, tightly sealed, and a roof on top for summer. Every fifty paces, place a catapult with an iron pivot. Every fifty paces, build a well-screen surrounded by a wall eight chi high. Every fifty paces, store a square of supplies secured with bolts and locks. Every fifty paces, pile no less than three hundred shi of firewood, well coated with mud so that enemy fire cannot damage it.
Every hundred paces, build a siege tower (longcong) rising five zhang from the ground, in three stories, with a front eight chi wide at the base and thirteen chi at the rear, tapering upward accordingly. Every hundred paces, build a wooden tower nine chi wide at the front and seven chi high, projecting twelve chi beyond the city wall. Every hundred paces, dig a well with ten jars connected by wooden channels. Provide a hundred water vessels holding four to six dou each. Every hundred paces, pile fifty large stalks over two circumferences thick. Every hundred paces, build a shelter (lu) four chi wide and eight chi high, to serve as a battering-ram path. Every hundred paces, build a thousand hidden firing positions (youfen) three chi wide and four chi high. Every two hundred paces, build a standing tower twenty-five chi and two cun wide inside the city, twenty chi long, projecting five chi beyond the pivot.
The wall-walk must be three to four paces wide to allow troops to move and fight. Build parapets (bini) three chi wide and two chi and five cun high. Build steps two chi and five cun high, three chi wide and long, with outer approaches six chi wide. At the four corners of the wall, build five-chi-high platforms where the four commandants (wei) are stationed. Every seven chi on the wall, place a barrier one zhang and five chi long with three chi buried, set five cun from the battlements, with twelve-chi posts and six-chi arms. Drill a half-post with a hole, leaving five cun at the rear. Drill two holes in the post so that the front end of the barrier post sits four cun below the battlement. Dig channels and pits for the barriers, cover them with tiles, and in winter protect them from cold with straw – all awaiting orders. If tiles are used for the pits, cover them accordingly.
Every thousand paces on the wall, place a signal marker one zhang long, held by a water-disposal man who waves it. Every fifty paces, build a latrine connected to the cesspit below; those using it must not carry anything. Every thirty paces on the wall, place a catapult; where the main assault comes, do not limit the number. Every fifty paces, build a stairway two chi and five cun high and ten paces long. Every fifty paces, build a watchtower, and station brave and strong men there in double strength. Every hundred paces, build an earthen tower with an outer gate leading to the tower, flanked by barriers on both sides. Add a catapult screen to the tower, with a walkway projecting outward for rescue operations.
On the wall, there must be no buildings or anything that could provide cover for hiding. Remove all such structures. Below the city, within a hundred paces of the moat along the roads, demolish all walls and cut down all trees, large and small. Where the enemy is likely to approach – along narrow paths, nearby routes, or open ground before the city – build guard towers and plant bamboo stakes in the ground.
Build a large tower in the courtyard below the command hall, high enough to overlook the city, with a surrounding walkway below. Receive visitors in the central hall and keep them waiting. Regularly summon the three elders who are in the refuge palace, consult with them on plans, and when their virtue and strategies are in accord, admit them to the refuge. Once admitted to the defense, they must not walk the walls or leave their quarters. All defenders must carefully assess where the walls are low and the moats shallow, and adjust their deployments accordingly. Use morning and evening roll-calls with singing as the signal system, and rotate personnel when numbers are low.
The defensive deployment: every fifty paces, assign ten adult men, twenty able-bodied women, and ten old and young – forty people per fifty paces. The ground-level tower troops should be one man per pace, so twenty men per twenty paces. Scale this ratio to the size of the city, and it will be sufficient for defense.
When the enemy presses against the wall and swarms up like ants, if the defender knows in advance, the defender has the advantage and the attacker is disadvantaged. When the enemy attacks along siege ramps, even with a hundred thousand troops, they will not attack with more than four columns. The widest approach is five hundred paces, the middle is three hundred paces, and the narrowest is fifty paces. For any approach less than a hundred and fifty paces, the defender has the advantage and the attacker is in difficulty. Against a five-hundred-pace column, deploy a thousand men, two thousand able-bodied women, and a thousand old and young – four thousand in all – and it will be sufficient to respond. This is the calculation for defending an approach. Assign the old and young who cannot fight to guard sections of the wall not facing the main assault.
When the city is under siege, issue clear pass-chits (tianzhang) so that all officials and people know them. Any group of one to a hundred or more leaving the city without a pass-chit, or with people not on their roster, or with forged chits, must be stopped by any commander of a thousand or above. Anyone who passes or any official or soldier who accompanies them shall be executed, and the matter must be reported in full to superiors. This is one of the most important prohibitions of siege defense, for it is where treachery arises, and it must be scrutinized carefully.
On the wall, build firing holes (jue xue) three chi below the battlements, widened on the outside, every five paces. The holes should be large enough to hold a torch-bundle, six chi high or three chi low, with spacing adjusted as needed. Block the outer trench, seven chi from the barrier, and install a suspended beam. Where the city is too narrow to dig a trench, do not dig one. Every thirty paces on the wall, build a covered stove. Each man should have a torch-bundle five joints long. When the enemy is below the wall and the drum sounds, ignite the bundles. At the second drum, thrust the bundles into the firing holes to illuminate the outside.
All catapults must have iron fittings. The catapult posts are one zhang and seven chi long, with four chi buried. The main beam is three to three and a half zhang long, the horse-cheek (majia) two chi and eight cun long. Test the catapult’s force and set the counterweight accordingly, with three-quarters of the weight above. For smaller catapults, the beam is three chi long with two-thirds to three-quarters above, and the horse-cheek in the middle third. The horse-cheek is two chi and eight cun long; beams of twenty-four chi or less are not used. Construct the counterweight frame from large wagon wheels. The catapult pivot is one zhang and two chi and five cun long. All catapults must have iron fittings; those who repair them are stationed there.
When the enemy builds earthen siege ramps, construct water conduits four chi deep, firmly packed and buried, every ten chi, covered with tiles and awaiting orders. Take large timber two chi and four fen thick, and twelve chi or more in length. Burn the base well. These are called “long followers” (changcong). Place thirty of them every fifty paces.
Wooden bridges should be three zhang long, no fewer than fifty. Again, order the soldiers to hastily build ramparts and cover them with tiles. Use tile and wooden jars holding ten sheng or more – place ten every fifty paces, filled with water for use. Of the fifty-two items, place two every ten paces.
Below the city, the families in the neighborhoods shall each protect their surroundings – left, right, front, and rear – just as on the wall. If the city is small and the population large, send the old and weak to take refuge in the interior of the state or in other large cities.
When the enemy arrives and an attack is certain, the defender shall first clear the city outskirts, but shall not burn anything. When the enemy is at the foot of the wall, rotate the officials and soldiers at their posts, but do not change their provisions; the providers shall not go up the wall.
When the enemy is at the foot of the wall, collect all basins, jars, and farming implements and pile them below the city – one pile every hundred paces, five hundred piles in total. Inside the city gate there shall be no buildings; build surrounding structures for the gate officials.
Four chi makes a parapet. Build internal walkways and gates. Two bolts and one battlement.
Clear the area outside the city grounds. Within a hundred paces of the moat, demolish all walls and cut down all trees, large and small, removing them entirely. Where the enemy is likely to approach – along narrow paths, nearby routes, or open ground before the city – build guard towers and plant bamboo stakes in the ground.
Build a large tower in the courtyard below the command hall, high enough to overlook the city, with a surrounding walkway below. Receive visitors in the central hall and keep them waiting. Regularly summon the three elders who are in the refuge palace, consult with them on plans, and when their virtue and strategies are in accord, admit them to the refuge. Once admitted to the defense, they must not walk the walls or leave their quarters.
All defenders must carefully assess where the walls are low and the moats shallow, and adjust their deployments accordingly. Use morning and evening roll-calls with singing as the signal system, and rotate personnel when numbers are low.
The defensive deployment: every fifty paces, assign ten adult men, twenty able-bodied women, and ten old and young – forty people per fifty paces. The ground-level tower troops should be one man per pace, so twenty men per twenty paces. Scale this ratio to the size of the city, and it will be sufficient for defense.
When the enemy presses against the wall and swarms up like ants, if the defender knows in advance, the defender has the advantage and the attacker is disadvantaged. When the enemy attacks along siege ramps, even with a hundred thousand troops, they will not attack with more than four columns. The widest approach is five hundred paces, the middle is three hundred paces, and the narrowest is fifty paces. For any approach less than a hundred and fifty paces, the defender has the advantage and the attacker is in difficulty. Against a five-hundred-pace column, deploy a thousand men, two thousand able-bodied women, and a thousand old and young – four thousand in all – and it will be sufficient to respond. This is the calculation for defending an approach. Assign the old and young who cannot fight to guard sections of the wall not facing the main assault.
When the city is under siege, issue clear pass-chits so that all officials and people know them. Any group of one to a hundred or more leaving the city without a pass-chit, or with people not on their roster, or with forged chits, must be stopped by any commander of a thousand or above. Anyone who passes or any official or soldier who accompanies them shall be executed, and the matter must be reported in full to superiors. This is one of the most important prohibitions of siege defense, for it is where treachery arises, and it must be scrutinized carefully.
On the wall, build firing holes three chi below the battlements, widened on the outside, every five paces. The holes should be large enough to hold a torch-bundle, six chi high or three chi low, with spacing adjusted as needed. Block the outer trench, seven chi from the barrier, and install a suspended beam. Where the city is too narrow to dig a trench, do not dig one.
Every thirty paces on the wall, build a covered stove. Each man should have a torch-bundle five joints long. When the enemy is below the wall and the drum sounds, ignite the bundles. At the second drum, thrust the bundles into the firing holes to illuminate the outside.
All catapults must have iron fittings. The catapult posts are one zhang and seven chi long, with four chi buried. The main beam is three to three and a half zhang long, the horse-cheek two chi and eight cun long. Test the catapult’s force and set the counterweight accordingly, with three-quarters of the weight above. For smaller catapults, the beam is three chi long with two-thirds to three-quarters above, and the horse-cheek in the middle third. The horse-cheek is two chi and eight cun long; beams of twenty-four chi or less are not used. Construct the counterweight frame from large wagon wheels. The catapult pivot is one zhang and two chi and five cun long. All catapults must have iron fittings; those who repair them are stationed there.
When the enemy approaches the moat, construct water conduits four chi deep, firmly packed and covered, at intervals of ten chi; cover them with tiles and await orders. Take large timber with a circumference of two chi and four fen, and hollow them out in advance; place charcoal fire inside, join them together, and hurl them using the Jiche (catapult).
Construct “Swift Plow” projectiles, two chi and five cun long, with a circumference of two wei or more. Prepare “Zhuo Yi” (barbed stakes): the stakes should be seven cun long, spaced six cun apart, with their tips sharpened. Prepare “Dog Runners” (Gouzou): seven cun wide, one chi and eight cun long, with claws four cun long; attach dog-ears to them.
Master Mo Zi said: “The method of defending a city requires counting the timber within the city. What ten men can lift is one ‘qie’ (unit of weight/capacity); what five men can lift is five ‘qie’. For all matters of weight and lightness, use ‘qie’ to represent the number of men required. For carrying firewood, assign proper ‘qie’ to the strong and the weak, so that each matches their capacity. In all matters of weight and capacity, officials and people should each obtain their proper role. In times of food shortage within the city, the load of the qie shall be greatly reduced.
Dig a large trench five paces from the city gate. In high ground, make it three zhang deep; in low ground, dig down to the water level. Place caltrops (thorns) within it. On top, build a lifting beam and rig it with mechanisms. Cover it with brushwood and earth to make it look like a passable road. Have ditches and ramparts on the sides so that it cannot be bypassed. Make the exit narrow and constricted.
When the enemy enters, pull the mechanism to release the beam, and the enemy can be captured. The enemy will be terrified and filled with suspicion, and consequently will disperse.”
Note
This chapter records Mozi’s talk with disciple Qin Guli on city defense. It lists twelve siege tactics and matching countermeasures, detailing fortifications, weapons, manpower allocation and fourteen essential defense prerequisites.
Mo Zi (墨子, c. 468–376 BCE):
Born Mo Di (墨翟), he was a philosopher, educator, scientist, and military strategist of the late Spring and Autumn / early Warring States period. He was either from the State of Song (modern Shangqiu, Henan) or the State of Lu (modern Tengzhou, Shandong). He founded the Mohist school, whose core doctrines included universal love, condemnation of offensive warfare, and practical defensive warfare. The chapter “Gongshu” records his famous journey to the State of Chu to stop an attack on Song, where he demonstrated his defensive expertise against the inventor Gongshu Ban.
Qin Guli (Qin Huali, 禽滑釐):
Qin Guli, Mo Zi’s most prominent disciple. According to “Preparing against Ladders” (备梯), he served Mo Zi for three years with great devotion – “his hands and feet became calloused, his face turned dark” – before daring to ask about the Way of Defense. He appears as the questioner in several of the city-defense chapters, serving as Mo Zi’s interlocutor.
The Mohist School:
One of the major philosophical schools of the Warring States period, often regarded as the “philosophy of the laboring class.” The Mozi was originally recorded as 71 chapters in the Hanshu Yiwenzhi (汉书·艺文志), but the received text contains only 53 chapters, with 18 lost. The city-defense chapters (Part V, chapters 52–71) form a systematic treatise on defensive warfare, unique in pre-Qin literature.
“Mo Shou” – “Mo’s Defense” (墨守) :
Mo Zi’s reputation as the supreme authority on defensive warfare was so great that the term “Mo Shou” came to mean any impregnable defense in later Chinese usage. This contrasts with Sun Zi’s offensive-oriented military theory, forming a complementary pair in traditional Chinese military thought.
The Twelve Methods of Attack (十二攻法):
The chapter enumerates twelve siege techniques commonly used in the Warring States period – siege towers, grappling hooks, battering rams, scaling ladders, earthen ramps, water attacks, tunneling, sudden sorties, hollow breaches, swarming assaults, covered wagons, and assault chariots. These reflect the highly developed state of siege warfare technology in ancient China.
The Fourteen Conditions for Defense (守城十四者):
Mo Zi’s systematic list of fourteen prerequisites for a defensible city – ranging from physical infrastructure (walls, moats, provisions) to social conditions (harmony between officials and people, trustworthy governance, clear rewards and punishments) – represents an early example of integrating military, political, and social factors into a unified defense theory.
“The Phoenix Does Not Appear” (凤鸟之不出):
In ancient Chinese cosmology, the phoenix was a mythical bird whose appearance signaled the arrival of a sage-king and a golden age. Its absence, as Qin Guli laments, symbolizes the moral decay of the age – the collapse of the Zhou order and the descent into chaotic warfare among the feudal lords. This allusion echoes Confucius’ own lament: “The phoenix does not come; the River does not produce a chart. It is all over with me!” (凤鸟不至，河不出图，吾已矣夫).
“The Feudal Lords Betray the States of Yin and Zhou” (诸侯畔殷周之国):
This refers to the breakdown of the feudal hierarchy established under the Shang (Yin) and Zhou dynasties. By the Warring States period, the authority of the Zhou king had become nominal, and the regional lords operated as independent powers, engaging in wars of conquest. This historical backdrop motivates Qin Guli’s urgent question about defending small states.
“Host and Guest” Terminology:
Throughout the chapter, the defender is consistently called the “host” and the attacker the “guest”. This metaphor reflects the Mohist view that defensive warfare is inherently just – the host fights on his own ground to protect his people, while the guest is the aggressor. This linguistic convention permeates all the city-defense chapters.
Mohist Military Engineering:
Unlike other philosophical schools, Mohism possessed a highly systematic and practical military doctrine. Chapter 52 reads like an ancient military engineering manual, detailing exact measurements, logistical requirements, and mechanical designs. It reflects the Mohist belief that defensive warfare is a moral imperative to protect the weak from unprovoked aggression.
Total War and Civilian Mobilization:
The text illustrates the concept of total mobilization. Women, the elderly, and children are systematically integrated into the defense logistics and combat support (e.g., 2,000 women per 500-pace attack front). Private property (timber, stones) is requisitioned, and civilian infrastructure outside the city is deliberately destroyed to deny cover to the enemy.
Meritocratic and Strict Military Discipline:
The chapter emphasizes severe punishments (e.g., execution for failing to keep watch, executing unauthorized exits) alongside clear rewards. It also highlights the Mohist principle of matching tasks to physical capabilities, ensuring that the strong and weak carry loads proportional to their strength.
禽滑釐问于子墨子曰：“由圣人之言，凤鸟之不出，诸侯畔殷周之国，甲兵方起于天下，大攻小，强执弱，吾欲守小国，为之奈何？”子墨子曰：“何攻之守？”禽滑釐对曰：“今之世常所以攻者：临、钩、冲、梯、堙、水、穴、突、空洞、蚁傅、轒辒、轩车，敢问守此十二者奈何？”子墨子曰：“我城池修，守器具，推粟足，上下相亲，又得四邻诸侯之救，此所以持也。且守者虽善，则犹若不可以守也。若君用之，守者又必能乎守者，不能而君用之，则犹若不可以守也。然则守者必善而君尊用之，然后可以守也。”
凡守围城之法，厚以高，壕池深以广，楼撕揗，守备缮利，薪食足以支三月以上，人众以选，吏民和，大臣有功劳于上者多，主信以义，万民乐之无穷。不然，父母坟墓在焉；不然，山林草泽之饶足利；不然，地形之难攻而易守也；不然，则有深怨于适而有大功于上；不然，则赏明可信而罚严足畏也。此十四者具，则民亦不宜上矣，然后城可守。十四者无一，则虽善者不能守矣。
故凡守城之法，备城门，为县门，沈机；长二丈，广八尺，为之两相如；门扇数，令相接三寸；施土扇上，无过二寸。堑中深丈五，广比扇，堑长以力为度，堑之末为之县，可容一人所。客至，诸门户皆令凿而慕孔，孔之，各为二慕二，一凿而系绳，长四尺。城四面四隅皆为高磨燍，使重室子居其上候适，视其态状与其进左右所移处，失候，斩。适人为穴而来，我亟使穴师选本，迎而穴之，为之且内弩以应之。
民室杵木瓦石，可以盖城之备者，尽上之，不从令者斩。昔筑，七尺一居属，五步一垒，五筑有锑，长斧柄长八尺。十步一长镰，柄长八尺。十步一斗，长椎，柄长六尺，头长尺，斧其两端。三步一大铤，前长尺，蚤长五寸。两铤交之，置如平，不如平不利，兑其两末。穴队若冲队，必审如攻队之广狭，而令邪穿其穴，令其广必夷客队。
疏束树木，令足以为柴抟，毋前面树，长丈七尺一，以为外面，以柴抟从横施之，外面以强涂，毋令土漏。令其广厚，能任三丈五尺之城以上。以柴木土稍杜之，以急为故。前面之长短，豫蚤接之，令能任涂，足以为堞，善涂其外，令毋可烧拔也。
大城丈五，为闺门，广四尺。为郭门，郭门在外，为衡，以两木当门，凿其木，维敷上堞。为斩县梁，令穿断城，以板桥邪穿外，以板次之，倚杀如城报。城内有傅壤，因以内壤为外。凿其间，深丈五尺，室以樵，可烧之以待适。
令耳属城，为再重楼，下凿城外堞，内深丈五，广丈二。楼若令耳，皆令有力者主敌，善射者主发，佐皆广矢。治裾诸，延堞，高六尺，部广四尺，皆为兵弩简格。转射机，机长六尺，貍一尺。两材合而为之辒，辒长二尺，中凿夫之为道臂，臂长至桓。二十步一，令善射之者佐，一人皆勿离。
城上百步一楼，楼四植，植皆为通舄，下高丈，上九尺，广、丧各丈六尺，皆为宁。三十步一突，九尺，广十尺，高八尺，凿广三尺，表二尺，为宁。城上为攒火，夫长以城高下为度，置火其末。城上九尺一弩、一戟、一椎、一斧、一艾，皆积参石、蒺藜。渠长丈六尺，夫长丈二尺，臂长六尺，其貍者三尺。树渠毋傅堞，五寸。藉莫长八尺，广七尺，其木也广五尺，中藉苴为之桥，索其端；适攻，令一人下上之，勿离。城上二十步一藉车，当队者不用此数。
城上三十步一垄灶。持水者必以布麻斗、革盆，十步一。柄长八尺，斗大容二斗以上到三斗。敝裕、新布长六尺，中拙柄，长丈，十步一，必以大绳为箭。城上十步一鈂。水缻，容三石以上，小大相杂。盆、蠡各二财。为卒干饭，人二斗，以备阴雨，面使积燥处。令使守为城内堞外行餐。置器备，杀沙砾、铁，皆为坏斗。令陶者为薄缻，大容一斗以上至二斗，即用取，三秘合束。坚为斗城上隔。栈高丈二，剡其一末。为闺门，闺门两扇，令可以各自闭也。
救闉池者，以火与争，鼓橐。冯埴外内，以柴为燔。灵丁，三丈一，火耳施之。十步一人，居柴内弩；弩半，为狗犀者环之。墙七步而一。
救车火，为烟矢射火城门上，凿扇上为栈，涂之，持水麻斗、革盆救之。门扇薄植，皆凿半尺，一寸一涿弋，弋长二寸，见一寸，相去七寸，厚涂之以备火。城门上所凿以救门火者，各一垂水，火三石以上，小大相杂。
门植关必环锢，以锢金若铁鍱之。门关再重，鍱之以铁，必坚。梳关，关二尺，梳关一苋，封以守印，时令人行貌封，及视关入桓浅深。门者皆无得挟斧、斤、凿、锯、椎。
城上二步一渠，渠立程，丈三尺，冠长十丈，辟长六尺。二步一荅，广九尺，袤十二尺。二步置连梃、长斧、长椎各一物；枪二十枚，周置二步中。二步一木弩，必射五十步以上。及多为矢，节毋以竹箭，楛、赵、樜、榆，可。盖求齐铁夫，播以射冲及栊枞。
二步积石，石重千钧以上者，五百枚，毋百，以亢，疾犁、壁皆可善方。二步积苙，大一围，长丈，二十枚。五步一罂，盛水。有奚，奚蠡大容一斗。五步积狗尸五百枚，狗尸长三尺，丧以弟，瓮其端，坚约弋。十步积抟，大二围以上，长八尺者二十枚。
二十五步一灶，灶有铁鐕，容石以上者一，戒以为汤。及持沙，毋下千石。三十步置坐候楼，楼出于堞四尺，广三尺，广四尺，板周三面，密傅之，夏盖其上。五十步一藉车，藉车必为铁纂。五十步一井屏，周垣之，高八尺。五十步一方，方尚必为关籥守之。五十步积薪，毋下三百石，善蒙涂，毋令外火能伤也。
百步一栊枞，起地高五丈，三层，下广前面八尺，后十三尺，其上称议衰杀之。百步一木楼，楼广前面九尺，高七尺，楼吻居坫，出城十二尺。百步一井，井十瓮，以木为系连。水器容四斗到六斗者百。百步一积杂秆，大二围以上者五十枚。百步为橹，橹广四尺，高八尺，为冲术。百步为幽膹，广三尺高四尺者千。二百步一立楼，城中广二丈五尺二，长二丈，出枢五尺。
城上广三步到四步，乃可以为使斗。俾倪广三尺，高二尺五寸。陛高二尺五，广长各三尺，远广各六尺。城上四隅童异，高五尺，四尉舍焉。城上七尺一渠，长丈五尺，貍三尺，去堞五寸；夫长丈二尺，臂长六尺。半植一凿，内后长五寸。夫两凿，渠夫前端下堞四寸而适。凿渠、凿坎，覆以瓦，冬日以马夫寒，皆待命。若以瓦为坎。
城上千步一表，长丈，弃水者操表摇之。五十步一厕，与下同圂。之厕者不得操。城上三十步一藉车，当队者不用。城上五十步一道陛，高二尺五寸，长十步。城上五十步一楼撕，撕勇勇必重。土楼百步一，外门发楼，左右渠之，为楼加藉幕，栈上出之以救外。城上皆毋得有室，若也可依匿者，尽除去之。城下州道内百步一积薪，毋下三千石以上，善涂之。城上十人一什长，属一吏士，一帛尉。百步一亭，高垣丈四尺，厚四尺，为闺门两扇，令各可以自闭。亭一尉，尉必取有重厚忠信可任事者。二舍共一井爨，灰、康、粃、杯、马矢，皆谨收藏也。
城上之备：渠谵、藉车、行栈、行楼、到、颉皋、连梃、长斧、长椎、长兹、距、飞冲、县□、批屈。楼五十步一，堞下为爵穴，三尺而一。为薪皋，二围，长四尺半，必有洁。瓦石重二升以上上。城上，沙五十步一积。灶置铁鐟焉，与沙同处。木大二围，长丈二尺以上，善耿其本，名曰长从，五十步三十。木桥长三丈，毋下五十。复使卒急为垒壁，以盖瓦复之。用瓦木罂，容十升以上者，五十步而十，盛水且用之。五十二者，十步而二。
城下里中家人，各葆其左右前后，如城上。城小人众，葆离乡老弱国中及他大城。寇至，度必攻，主人先削城编，唯勿烧。寇在城下，时换吏卒署，而毋换其养，养毋得上城。寇在城下，收诸盆瓮耕积，之城下，百步一积，积五百。城门内不得有室，为周室桓吏。四尺为倪，行栈内閈，二关一堞。除城场外，去池百步，墙垣树木小大俱坏伐，除去之。寇所从来，若昵道、傒近若城场，皆为扈楼，立竹箭天中。
守堂下为大楼，高临城，堂下周散道。中应客，客待见。时召三老在葆宫中者，与计事得先，行德计谋合，乃入葆。葆入守，无行城，无离舍。诸守者审知卑城浅池而错守焉。晨暮卒歌以为度，用人少易守。守法：五十步丈夫十人、丁女二十人、老小十人，计之五十步四十人。城下楼卒，率一步一人，二十步二十人。城小大以此率之，乃足以守圉。
客冯面而蛾傅之，主人则先之知，主人利，客适。客攻以遂，十万物之众，攻无过四队者，上术广五百步，中术三百步，下术五十步。诸不尽百五步者，主人利而客病。广五百步之队，丈夫千人，丁女子二千人，老小千人，凡四千人，而足以应之，此守术之数也。使老小不事者，守于城上不当术者。
城持出必为明填，令吏民皆智知之。从一人百人以上，持出不操填章，从人非其故人，乃其稹章也，千人之将以上止之，勿令得行。行及吏卒从之，皆斩，具以闻于上。此守城之重禁之，夫奸之所生也，不可不审也。
城上为爵穴，下堞三尺，广其外，五步一。爵穴大容苴，高者六尺，下者三尺，疏数自适为之。塞外堑，去格七尺，为县梁。城陕不可堑者勿堑。城上三十步一聋灶。人擅苣，长五节。寇在城下，闻鼓音，燔苣。复鼓，内苣爵穴中，照外。诸藉车皆铁什。藉车之柱长丈七尺，其貍者四尺；夫长三丈以上至三丈五尺，马颊长二尺八寸，试藉车之力而为之困，失四分之三在上。藉车，夫长三尺，四二三在上，马颊在三分中。马颊长二尺八寸，夫长二十四尺，以下不用。治困以大车轮。藉车桓长丈二尺半。诸藉车皆铁什，复车者在之。
寇闉池来，为作水甬，深四尺，坚慕貍之，十尺一，覆以瓦而待令。以木大围长二尺四分而早凿之，置炭火其中合慕之，而以藉车投之。为疾犁投，长二尺五寸，大二围以上。涿弋，弋长七寸，弋间六寸，剡其末。狗走，广七寸，长尺八寸，蚤长四寸，犬耳施之。
子墨子曰：守城之法，必数城中之木，十人之所举为十挈，五人之所举为五挈，凡轻重以挈为人数。为薪樵挈，壮者有挈，弱者有挈，皆称其任。凡挈轻重所为，吏人各得其任。城中无食则为大杀。
去城门五步大堑之，高地三丈，下地至，施贼其中，上为发梁，而机巧之，比传薪土，使可道行，旁有沟垒，毋可逾越，而出佻且比，适人遂入，引机发梁，适人可禽。适人恐惧而有疑心，因而离。
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