《墨子》Vol. 14

This passage comes from the "Defensive Preparations of City Gates" chapter in Mozi, documenting the practical defensive techniques of the Mohist school. At the time, Mozi's disciple Qin Guli asked his teacher: In an era of chaotic warfare among feudal lords where the strong preyed on the weak, how could small states protect themselves?

Mozi first emphasized that the foundation of city defense lay in: maintaining strong walls and fortifications, stockpiling sufficient provisions, ensuring unity between rulers and ministers, and securing support from neighboring states. However, even with these conditions, success would remain elusive if the ruler failed to properly employ skilled defensive strategists.

The text then details the specifications for constructing gate defenses:

• City gates should be equipped with counterweighted suspension mechanisms (defensive devices), measuring two zhang (approx. 6 meters) in length and eight chi (approx. 2.4 meters) in width, installed symmetrically on both sides
• The crossbeams should be staggered with three cun (approx. 9 cm) of overlapping reinforcement
• The moat before the gate should be fifteen chi (approx. 4.5 meters) deep, matching the gate's width
• Observation ports should be carved above the gate, each fitted with two four-chi (approx. 1.2 meters) ropes
• Firefighting equipment like sandbags and water basins must be prepared, with gate surfaces thickly plastered for fireproofing
• Crossbeams require metal reinforcement with double iron bands
• Defensive trenches (qu) should be built along the walls every two paces (approx. 3 meters), each trench standing three zhang three chi (approx. 10 meters) high

These measures demonstrate the Mohist practical wisdom of prioritizing defense within their philosophy of "condemning aggression" (fei gong), creating robust city defenses through meticulous calculations and standardized construction. The described "suspended counterweight mechanisms" and "interlocking barriers" represent advanced military engineering technology of the period.

This passage describes the specifications and layout of ancient city defense facilities, constituting detailed records of military fortification engineering. It primarily outlines the precise measurements required for deploying various defensive structures and weapons around city walls.

Defensive installations were arranged at regular intervals (such as every two bu, five bu, or ten bu): for instance, within a two-bu distance, one should place one each of lian ting (a long-handled weapon), long axe, and long awl, accompanied by twenty spears. At five-bu intervals, a gourd container capable of holding one dou of water was required, while every ten bu necessitated a stack of twenty thick wooden poles (each with a circumference exceeding two arm spans and measuring eight chi in length).

Key defensive structures included: iron war chariots (ji che) deployed every fifty bu, accompanied by a well enclosed within an eight-chi-high wall; every hundred bu required the construction of a five-zhang-high, three-story watchtower (long chuang) with an eight-chi-wide base and thirteen-chi rear section; as well as wooden watchtowers projecting twelve chi outward from the city walls.

The text particularly emphasizes stockpiling defensive materials: no fewer than five hundred stones (each weighing over thirty jin), at least three hundred dan of firewood and grass (properly treated for fire prevention), along with water containers capable of holding four to six dou (lian shui qi) and fifty large bundles of straw.

This systematic arrangement of defenses—from close-quarter weapon placements to distant observation posts, from ground-level fortifications to fire prevention measures—forms a comprehensive urban defense system. All dimensional specifications were strictly regulated, reflecting the highly organized nature of ancient military engineering.

This passage records detailed specifications and deployment methods for ancient city wall fortifications, primarily describing the dimensions, spacing, and functions of various defensive structures along the battlements.

At each corner of the city walls stood five-chi-high "Tongyi" defensive structures. Every seven chi, a fifteen-chi-long "Qu" drainage ditch was installed, buried three chi underground. Five cun in front of the battlements ("Die"), twelve-chi-long "Fu" defensive barriers were erected, featuring six-and-a-half-chi extensions called "arms." During winter, these ditches required tiling for frost protection.

The walls featured one "Biao" marker pole every thousand paces, with latrines every fifty paces. Defensive "Jieche" chariots were stationed every thirty paces, while two-and-a-half-chi-high, ten-pace-long stairways ("Daobi") appeared every fifty paces. Watchtowers contained outer gates every hundred paces, flanked by drainage channels on both sides.

Beneath the walls, each hundred-pace section stored no less than three thousand dan of grain in secure storage. The defensive organization assigned one squad leader per ten soldiers, with a fourteen-chi-high, four-chi-thick guard "Ting" post every hundred paces featuring double gates. Sentry post commanders were required to demonstrate absolute loyalty.

Defensive armaments included: Qu ditches, Jieche chariots, mobile siege bridges ("Xingzhan"), towers, long axes, and spike hammers. Battlements were spaced every fifty paces, with three-chi-high "Jueni" defensive installations beneath them. Stockpiles of firewood, tiles, and stones were mandatory, with cooking stoves every fifty paces.

Finally, preparations required large timbers (two-armspan circumference, twelve-chi length) and ceramic jars (minimum ten-sheng capacity), with ten water storage jars per fifty-pace section. All defensive installations demanded meticulous maintenance for wartime readiness.

This passage documents the specific defensive arrangements and city-guarding principles of ancient fortifications. First, the construction standards for city walls: every ten paces required double-layered walls, with tall defensive structures built at the four cardinal directions and four corners. Important observation rooms were constructed atop the walls, manned by dedicated sentinels to monitor enemy movements—any guard whose negligence allowed enemy infiltration would face execution.

Preparations for defensive materials were meticulous: every seven feet of wall required a set of defensive tools, with a bastion positioned every five paces, all five types of weapons fully stocked. Long axes with eight-foot handles were placed every ten paces; similarly, eight-foot-handled scythes were stationed every ten paces; long awls (similar to spears) had six-foot shafts with one-foot heads. All defensive structures had to be built thick and tall, moats dug deep and wide, and watchtowers constructed for durability. Food reserves had to sustain the city for at least three months.

Selection criteria for defenders prioritized officials with military merits who had earned the people's trust. The motivation for defending the city relied on either the people's attachment to their homeland (with ancestral graves nearby), the natural defensibility of the terrain, deep-seated hatred toward the enemy, or a clear system of rewards and punishments that inspired awe. Even small households within the city were organized into mutual defense networks like the wall guards.

Special attention was given to gate defenses: no buildings were allowed inside the gates, maintaining a four-foot-wide passageway. All obstacles within a hundred paces outside the city were cleared to prevent enemy exploitation. When enemies approached, observation towers (hulou) were erected atop the walls, and tall structures were built beneath the commander's hall to oversee the entire city. When receiving envoys, village elders (sanlao) and defense officials were summoned for joint deliberations.

Finally, Mo Di (Mozi) particularly emphasized consulting "tunnel specialists" (xueshi)—experts in tunnel warfare—as underground attacks and countermeasures were among the key tactics in ancient siege warfare. The entire passage meticulously illustrates the sophisticated urban defense system characteristic of the Warring States period, as represented by the Mohist school.

This passage from Mozi details specific methods for organizing city defense. Tall observation towers must be constructed within the city, and fourteen types of defensive facilities should be prepared—none can be omitted. For every fifty paces along the wall, deploy ten able-bodied men, twenty women, and ten elderly or children, totaling forty defenders per fifty-pace section. Below the walls, assign one person per pace, meaning twenty people for every twenty paces—this proportional distribution of forces is essential for holding the line.

When the enemy attacks, defenders must seize the initiative. No matter how large the attacking force, their main assault will focus on no more than four directions. Defensive zones are divided into three grades: upper-grade zones span five hundred paces, middle-grade three hundred paces, and lower-grade fifty paces. For troop allocation, a five-hundred-pace defensive line requires one thousand officers (dafu), two thousand women, and one thousand elderly and children—totaling four thousand defenders. The elderly and children are stationed along less critical wall sections.

Exiting the city requires a pass (mingtian), and both officials and civilians must be aware of this rule. Any group of over a hundred people leaving without a pass, or following unauthorized personnel, will face severe punishment. Commanders overseeing a thousand or more troops have the authority to halt violations, with offenders executed and the incident reported. This is a crucial defensive regulation that must be strictly enforced.

Reconnaissance of enemy movements is vital. Signs such as sudden wall-building, piled earth, or abruptly murky water may indicate tunneling. In such cases, immediately dig trenches inside the city at corresponding locations and sink wells every five paces, each reaching three chi below the water table. Use ceramic jars (ying) filled with water, covered with thin leather, and place them in the wells. Skilled listeners should crouch over the jars to detect tunneling sounds, then counter-dig in the identified direction. Additionally, prepare crescent-shaped ceramic pipes (yueming), each two and a half chi long, joined to form sealed conduits. Both inner and outer surfaces must be coated with mud to prevent air leaks, with this method applied to both sides of the tunnel.

This passage meticulously records the city defense systems of the Warring States period, including troop deployment, pass regulations, and countermeasures against tunneling. It reflects the Mohist school’s emphasis on defensive engineering in military strategy.

This passage describes ancient city defense methods against tunnel warfare, detailing how to construct smoke kilns to counter enemy tunneling attacks. Here are the specific procedures:

When defending a city and detecting enemy tunneling (xuegong), smoke kilns must be built at corresponding positions inside the walls. Each kiln should measure five chi (approximately 1.2 meters) in length, with ventilation ducts on both sides and an internal furnace chamber large enough to hold seven or eight bundles of mugwort. Each kiln requires four leather bellows (tuo) for air supply.

During construction, use a well sweep (jiegao, a lever tool) to compact the earth. When rapidly pumping smoke, ensure the flames remain bright. The bellows operators must not leave the furnace mouth, adjusting wooden boards according to the tunnel's height and width. Workers follow these boards while excavating, with perforations allowing smoke passage—hole density should maximize smoke effectiveness against enemies.

Upon encountering an enemy tunnel, immediately seal it with prepared materials. After blocking one opening, reposition the board to address the next. When hearing movement in tunnels, swiftly block forward passages. If enemies flood in, seal with firewood and mud mixtures to prevent them from burning the boards.

Technical specifics: Place one-chi-long mugwort bundles (23 cm) in the kiln, first building the furnace wall facing the tunnel. Dig wells every three zhang (7 meters) along the inner wall base, adjusting positions based on external conditions while maintaining higher interior elevation. Install three or four monitoring wells on the wall, with listeners pinpointing tunnel locations.

After confirming tunnel paths, use sturdy poles with sharp axes attached. Select three strong men to operate the well sweep for impact, pouring ten-plus dan (≈600 liters) of waste matter. Wells should contain mugwort filled only 70%, covered with basins to contain smoke while adjacent bellows operate rapidly. Reinforce with wheels, hemp ropes, and three-zhang (7-meter) iron chains with hook rings, suspended above enemy tunnel entrances.

Tunnel defenses stand seven chi five cun tall (1.8 meters), with pillars spaced one chi two cun apart (28 cm), every two sharing a stone base. Critical pillars should measure two-and-a-half wei in girth (≈1.1-meter circumference) for stability. Each defensive point requires two kilns, a command post with dedicated personnel, and water access. Use materials from two chariots to create fireproof coatings over the tunnel defenses.

(Note: Ancient unit conversions: 1 chi ≈ 23 cm, 1 zhang = 10 chi ≈ 2.3 m, 1 wei ≈ 45 cm circumference)

This passage documents ancient methods of constructing city fortifications, primarily describing defensive structures and the precise specifications for crafting siege defense equipment.

Regarding defensive structures: Inside the city walls, tunnels (xue) were dug four to five feet deep, featuring multiple layers of defensive mechanisms. These tunnels contained rotating gate mechanisms fueled by three bundles of mugwort, with personnel stationed at specific ambush points. Two leather bellows (tuo) were positioned beside the tunnels as defensive tools, requiring constant supervision.

The specifications for siege defense equipment were meticulously precise: Iron weapons measured four and a half feet in length, resembling the shape of iron armor. Iron rings serving as mechanisms were installed seven feet above the tunnels, while wells were dug at designated spots along the walls. Construction required a workforce of fifty, with an equal number of men and women cooperating.

Defensive installations on the city walls included: observation ports (juexue) placed every five paces—larger ones capable of holding torches, with heights varying between three to six feet. Drawbridges (xianliang) were set up seven feet from the outer moat (qian). Cooking stoves were installed every thirty paces along the walls, using torches (ju) five sections long, which were lit upon hearing drum signals for illumination.

Detailed specifications were given for siege engines (jiche): The main pillar measured seventeen feet in length, buried four feet underground. The longest lever (fu) could extend up to thirty-five feet, while the "horse cheek" component (majia) was two feet eight inches. During strength testing, three-quarters of the components had to remain in the upper section. Wheels required special reinforcement using large timber.

Finally, methods to counter enemy water attacks were outlined: Drainage channels (shuiyong) four feet deep were constructed, covered at intervals of ten feet. Throwing devices (jili) were crafted from timber of specific dimensions—two feet five inches in length with a circumference exceeding two arm spans. Another defensive device called "dog runs" (gouzou) measured seven inches in width and one foot eight inches in length.

These details showcase the high degree of specialization in ancient military engineering, where every component adhered to strict measurements. The comprehensive defensive system reflects the practical philosophy of the Mohist school, which placed great emphasis on the utility of fortifications.

The Mozi records methods of city defense: First, one must inventory the timber within the city walls. A load that ten men can lift is called a "ten-qie," while a load five men can lift is called a "five-qie." When transporting firewood and straw, the weight should be distributed according to the number of people, with both strong and weak laborers assigned tasks according to their capabilities. Officials must also participate in the transportation work. If the city is short on grain, deep trenches should be dug five paces outside the city gates—three zhang (approx. 6.9 meters) deep in elevated areas and to an appropriate depth in lower areas.

When defending the city, a retractable bridge (faliang) should be installed over the trench, controlled by a mechanism. Firewood and earth should be piled beside the bridge to create a passageway, with trenches dug and ramparts built on both sides to prevent enemies from scaling them. When the enemy attacks, pulling the mechanism to remove the bridge can capture the enemy, instilling fear and causing them to waver, ultimately leading to their collapse.

In the chapter "Preparation Against Elevated Attacks", Qinzi asks Mozi: If the enemy builds earthen platforms (yangqian) outside the city, advances under the cover of shields (menglü), and attacks with arrows, how should one respond? Mozi replies that this yangqian tactic is a foolish method—it only exhausts the enemy's own strength and poses little threat to the city's defense.

The defensive method is as follows: Construct watchtowers (liaowang tai) atop the city walls to monitor the yangqian, extending twenty chi (approx. 4.6 meters) to each side, with the towers standing thirty chi (approx. 6.9 meters) high. By using powerful crossbows and mechanical devices for defense, the yangqian assault can be repelled. Additionally, repeating crossbow carts (liannu che) should be prepared. These weapons have a square base measuring one chi (approx. 23 cm) per side, with a length matching the thickness of the city wall, featuring two axles and three wheels. The crossbow arms are level with the carriage, which stands eight chi (approx. 1.84 meters) tall, while the crossbow axle is positioned three chi five cun (approx. 80.5 cm) above the base. The repeating crossbow uses a bronze mechanism with a draw weight of one dan thirty jin (approx. 75 kg in modern terms). The bolts are ten chi (approx. 2.3 meters) long and fired using rope controls. This weapon is equipped with a sighting device (yi) to adjust the firing angle, making it exceptionally powerful.

(Note: In the text, dan is an ancient unit of weight, approximately 60 kg in modern terms; chi is a unit of length, approximately 23 cm.)

The classic Mohist text Mozi·Beiti records methods for defending against cloud-ladder siege tactics. Qin Guli (a disciple of Mozi) studied under the master for three years, his hands and feet calloused, his face darkened by exposure, yet he dared not inquire about defensive strategies. Once at the foot of Mount Tai, when Mozi hosted him with wine and meat, Qin Guli finally bowed and asked about the art of city defense.

Mozi first admonished: In ancient times, some defenders failed to care for their people internally or govern effectively externally, using few to resist many and weakness to oppose strength—ultimately perishing along with their states. He then detailed specific countermeasures when facing numerous and fierce enemies equipped with cloud-ladders and other siege engines:

Cloud-ladders are heavy machinery, difficult to maneuver. Defenders must construct "temporary walls" (improvised elevated barriers) and "observation towers" atop the city walls, secured with looped ropes, their width adjusted according to terrain. Standard temporary walls should be twenty chi high (approx. 4.6 meters), topped with six-chi-high parapets (battlements) extending twenty chi laterally.

The walls should feature "arrow slits" and defensive mechanisms called "Da," equipped with counter-impact vehicles. Each wall section deploys ten swordsmen and five shock troops, all selected for exceptional strength. Sharp-eyed observers monitor enemy movements, directing concentrated arrow volleys via drum signals. Defensive materials like rolling stones, sand-charcoal mixtures, torches, and boiling water must be prepared, with timely rewards and punishments for troops.

Countering cloud-ladders requires rapid response: six-chi parapets should mount mechanical blades triggered upon ladder contact; caltrop-hurlers spaced three chi apart operate via cart-pulled mechanisms; auxiliary defenses called "Pi" are deployed beyond the walls. With composed execution, cloud-ladder assaults can be repelled.

This account reflects the Mohist philosophy of "condemning aggression" through meticulous defensive technology, emphasizing coordinated engineering and tactics—a testament to Warring States military ingenuity.

This passage records ancient methods of constructing city fortifications and defensive tactics, primarily detailing how to build walls and establish defensive installations to repel enemy attacks.

A ten-foot-deep moat should be dug outside the city walls, with the moat walls being ten feet thick, ensuring all large and small tree roots are completely cleared. Defensive structures should be installed every twenty paces, each equipped with two five-foot-wide gates. Shallowly bury obstacles near the city gates for quick removal when needed. Hang torches every four feet along the walls, place stoves every five paces, and keep charcoal fires ready at the gates. Once all enemies have entered, set fire to the gates while simultaneously lowering the hanging torches.

During defense, drums serve as signals—soldiers advance or retreat upon hearing them. At midnight, beating drums and shouting from all sides of the walls can disorient the enemy. Soldiers should wear white clothing and use secret signals to identify each other, effectively countering siege ladders.

For flood prevention: Dig a circular moat eight paces wide within the city, adjusting its depth according to terrain to ensure proper drainage. Excavate deep channels in low-lying areas to divert water, installing ceramic wells to monitor external water levels. Prepare boats to form a fleet, each vessel manned by thirty crossbowmen. Select twenty strong soldiers per boat, armed with swords and armor. Take family members of elite troops as hostages beforehand to ensure their desperate resistance. When water levels rise, floodgates can be opened to unleash torrents against enemies, coordinated with archers atop the walls.

For surprise attack prevention: Install hidden gates (secret passages) every hundred paces along the walls, with kiln stoves built inside. Block these passages with two-wheeled carts, securing the wheels with wooden braces and waterproofing them with mud. Assign dedicated personnel to operate these hidden gates, using vehicles to barricade the passages.

This passage comes from the "Defense Against Tunnels" chapter in Mozi, primarily describing ancient methods to counter enemy tunnel attacks on city walls. Here's a simplified interpretation:

Inside the city gate, measure the width of the passageway and set up a kiln-stove about four to five chi (ancient Chinese feet) from the entrance. Pile firewood beside the stove to create its appearance. When enemies enter, lower a barrier to block the exit, then fan the flames to smoke them out.

Qin Guli (a disciple of Mozi) respectfully inquired: Ancient experts in siege warfare would tunnel in and burn the city walls by setting fires around support pillars. To defend against such tactics, prepare two types of iron spears: the front spear should be one chi long with five-cun (inch) barbs. When crossing two spears, keep them perfectly level—otherwise they'll be ineffective.

When digging defensive tunnels, adjust dimensions according to the enemy's tunnel width. Our tunnels should be spacious and level, reinforced with timber bundles. Erect 1.7-zhang (about 17 feet) wooden poles as outer walls, then reinforce horizontally with firewood bundles coated thickly with mud to prevent soil leakage. The tunnel must be wide and sturdy enough to withstand pressure from 3.5-zhang high walls.

Gate design: Main cities should have a 1.5-zhang high "inner gate" (smaller entrance) and a 4-chi wide "outer gate." Install crossbeams outside the outer gate secured by two wooden bars with drilled holes. On the wall, build a retractable suspension beam (drawbridge) extended outward with slanted planks.

Inside the city, dig 1.5-zhang deep pit chambers stocked with firewood to burn invading enemies. Construct double-layered towers along inner walls with 1.5-zhang deep, 1.2-zhang wide trenches beneath them. Station elite warriors and expert archers equipped with powerful bows and crossbows. Install rotating ballistae (defensive artillery) every twenty paces, each manned by specialists.

Every hundred paces along the wall, build a four-pillared watchtower—the lower level 1 zhang high, the upper level 9 chi, both 1.6 zhang wide—with enough space to garrison thirty soldiers. All defensive structures must be fireproof and sabotage-resistant.

This passage documents the construction standards and defensive configurations of ancient city fortifications, pertaining to military engineering techniques. Here is a modern interpretation of the key points:

Wall construction followed strict dimensional standards: each section advanced nine chi (an ancient unit of length), with walls ten chi wide and eight chi tall. Trenches were dug three chi wide, with two-chi-high marker poles serving as measurement references.

Defensive installations atop the walls included:

• A torch lighting system with lengths adjusted according to wall height
• Weapon stations every nine chi, each equipped with crossbows, halberds, iron maces, axes, and sickles
• Stockpiles of stones and caltrops (spiked defensive implements) as projectile weapons
• Defensive trenches measuring one zhang six chi long, with six-chi-long arms buried three chi underground

Battlement (die) construction requirements:

• No sloping crenellations—maintaining three chi of vertical height
• Installation of eight-chi-long, seven-chi-wide wooden protective boards (jiemo)
• Central rope bridges woven from cattails for personnel movement

Key defensive positions featured:

• One catapult (jieche) every twenty paces
• One stove station every thirty paces, wrapped in fireproof cloth
• One eight-chi spear every ten paces, replaced with large rope arrows at critical points
• One water storage vat (fou) every ten paces, holding over three dan (approx. 180 liters), paired with two ladles of different sizes

Logistical support measures:

• Dry rations stockpiled at two dou (approx. 15kg) per person
• Stockpiles of sand, stones, iron blocks and other defensive materials
• Ceramic containers (bo fou) holding one to two dou
• Double-leaf gate design allowing independent closure

Special defensive tactics:

• Coordinated torch signals and drum beats
• One crossbowman stationed in ambush every ten paces
• Immediate alert upon detecting suspicious tunnels
• Counter-tunnel tactics: ten-chi-deep detection wells every twenty paces
• Tunnel entrances reinforced with pine wood and double-layered iron caltrops

These specifications reflect the highly systematic nature of ancient military engineering. From wall structures to weapon deployment, from logistical support to emergency protocols, they formed a complete urban defense system.

The text describes the construction methods and defensive strategies of ancient city fortifications, focusing on how to build defensive works to repel enemy attacks.

When constructing city walls, a circular defensive barrier should be built on the outer perimeter using stacked stones, reaching a height of seven chi (about 7 feet), with crenellated parapets (the notched low walls atop battlements) added above. Instead of building stairs, suspended rope ladders should be used for ascending and descending. Furnaces must be prepared and wrapped in oxhide. Each furnace should have two large earthenware jars and be equipped with bellows for forced airflow. Forty furnaces should be arranged in groups of ten for smoke generation.

If enemy forces dig tunnels approaching within five hundred paces of the city walls, counter-tunnels must be excavated. Upon encountering enemies in the tunnels, they should be surrounded but not pursued—feign retreat while waiting for the furnace smoke to be ignited. Then quickly withdraw and seal the tunnel entrance, installing mechanical locks and leaving only one passage for friendly movement.

Dogs should be kept in the tunnels; their barking will signal enemy presence. Assign fifty defenders inside the tunnels and prepare six thick hemp ropes wrapped in oxhide for lifting and dropping objects. When tunnels reach the perimeter, prepare logs by the outer moat, cut into ten sections for use. Near tunnel entrances, keep four-chi-long (about 4 feet) iron axes and spades.

To counter enemy tunnels, use four-chi-long iron hooks. In narrow sections, defend with short spears, halberds, and crossbows. Once tunnels are breached, wield five-chi-long metal swords as weapons. Prepare wooden stakes with sharp spikes to obstruct enemies. Additionally, bury earthen jars weighing at least thirty jin (about 33 lbs) at intervals of one zhang (about 10 feet) to monitor enemy movements.

Tunnels should be eight chi high (about 8 feet) and properly equipped with defenses. Protect tunnel entrances with whole oxhide and straw mats. Prepare two covers and stockpile mugwort to ignite for smoke dispersal. Keep three-chi-long axes as weapons. Each tunnel entrance should be equipped with forty tools, including axes, saws, chisels, and hoes. Iron grates should also be prepared for additional protection.

Build watchtowers ten and a half zhang tall (about 105 feet) and four chi wide (about 4 feet), with eight horizontal openings. Prepare torches and hemp ropes for illumination. If enemies use smoke, protect the eyes with vinegar. Place large basins in the tunnels containing at least four dou (about 16 liters) of vinegar to counteract smoke and safeguard vision.

Gongshuli (a disciple of Mozi) bowed respectfully twice and asked: "When the enemy's forces vastly outnumber ours and have already reached the city walls to begin scaling them—when they've ordered their rear troops to first cut down the moat bridges to create passageways, dug tunnels beneath the walls as strongholds, with their vanguard maintaining relentless assault while their rear rains down arrows—how should we defend against such a situation?"

Mozi replied: "You're asking about methods to counter the 'ant-style siege,' aren't you? This assault tactic often catches defending generals unprepared. For defense, we must prepare multiple lines of resistance: use mobile watchtowers (linche) to shoot the enemy, deploy catapults (xiaoji) to launch projectiles, employ rolling logs (taisi) to crush attackers, utilize fire attacks, and pour down sand and stones. These measures can effectively thwart the ant-style assault."

For specific defensive preparations, we should construct "hanging defense platforms" (xianpi) using two-inch-thick wooden planks—three chi long front and back, five chi wide left and right, and five chi tall—with curved bottoms for easy mobility. Install wheel axles one chi six cun in diameter, operated by one person. Equip both ends with double-edged square weapons suspended by iron chains. The platform should have mechanisms controlled by four strong men for raising and lowering.

Place one such defense platform every twenty bu. At the enemy's main assault points, prepare "defensive barriers" (leida) every six bu—each two zhang in length and width. Construct crossbeams from wood, weave with thick hemp ropes coated in fireproof mud, and install iron hooks at both ends. When enemies climb like ants, ignite the coverings and drop them while counterattacking with long spears (lianchi) and hooked sickles (chaoda).

We must also prepare two-wheeled war chariots with widely spaced axles to block enemy troops. Reinforce both ends of the chariots and coat the wheels with fireproof material. Fill the carriage with elm wood or thorns—called "fire bundles" (huozuo). Another method involves preparing boiling water to pour on climbing enemies while cutting their ropes to make them fall, then sending out brave warriors to attack.

On the city walls, promptly repair any damaged sections. Below the walls, prepare five-chi-long iron hooks (chanzhao) with sharpened tips, arranged in five rows with three-chi spacing, buried three chi deep. Install "interlocking defense devices" (lianshu)—five chi long and ten chi wide; "posts" (ting) two chi long and six cun thick; ropes two chi long; "hammers" (chui) with six-chi handles and one chi five cun heads; and axes with six-chi handles that must remain razor-sharp.

In the rear, erect protective screens one zhang two chi wide and one zhang six chi tall, with four-cun overhanging eaves and one-chi overlapping ends—arranged not like fish scales with only three overlaps. Secure them with twenty-six-chi wooden ropes. Fill any gaps in the screens with wooden planks, regularly sun-drying them to maintain dryness.

This passage comes from Mozi Volume 14, primarily discussing ancient methods of constructing defensive fortifications and tactics for defending cities. Here is the modern interpretation:

When repairing city walls, first reinforce damaged sections by embedding ten-foot wooden stakes. Support each damaged wall segment with timber, installing protective boards (卢薄) measuring eight feet high and seven inches wide on the exterior, secured with ropes at intervals of one foot. Suspended boulders (楼罗石) should be hung at high points on the walls, and defensive mechanisms installed on the inner side of the fortifications.

Around the perimeter, embed sharpened wooden stakes (杜格) four feet high—some as tall as ten feet—arranged in alternating lengths with their tips sharpened. Both the interior and exterior should be reinforced with thick mud. Build plank roads in front of the walls and construct curved watchtowers (曲裏) at corners, placing observation posts every five paces and concealed soldier pits (爵穴) every twenty paces.

Additional defensive measures include: setting up ten-foot-thick barriers (薄) ten feet outside the city walls, felling trees to make ten-foot stakes, and embedding them deep into the ground for stability. Establish ambush points (杀) every twenty paces, each with two gates five paces wide, designed for easy removal. Suspend large boulders on the walls facing the enemy’s main assault direction, place stoves every five paces, and keep charcoal ready at the stove openings.

During battle, once enemy troops enter firing range, ignite the fire piles at the gates and then drop suspended torches. If the enemy retreats from the flames but attacks again, repeat the fire assault. Should the enemy collapse in retreat, dispatch elite troops from hidden gates to pursue. The entire army must act in unison according to drum signals. At night, set ambushes while beating drums and shouting from all sides of the walls to disorient the enemy—this often leads to successful kills or captures of enemy commanders. Soldiers identify each other using specific clothing and signals.