墨子 MOZI

Qin Zi bowed repeatedly and said: ‘May I ask about the men of old who were skilled in attack and tunnelled through the ground to enter [the city], placing posts which they set on fire in order to damage our wall. When the wall was damaged, what did those within the city do?’ Master Mo replied: ‘Are you asking about the defence against the tunnelling of earth? In preparing against tunnelling, erect a high tower within the wall to maintain a vigilant surveillance of the enemy. If the enemy brings about changes, for example builds up walls of an extraordinary amount of earth or causes the water in the moat to become unusually muddy, this indicates the tunnelling of earth. Urgently dig a channel within the wall and excavate tunnels to counter this. Every 5 bu dig a well within the wall, making it close enough to the wall. [If the wall is on] high ground, [the wells should be] 1 zhang 5 chi deep; if it is on low ground, they should reach to 3 chi below the water level and stop. Direct potters to make ying (jars, geophones) with a capacity of 40 dou or more, cover them tightly with thin rawhide and place them in the wells. Get those with sharp hearing to lie prostrate and listen in order to get detailed information about where the [enemy] tunnels are situated, then dig [counter-]tunnels to meet them.’

Direct potters to make tiled pipes 2 chi 5 cun in length with a diameter of 6 wei (spans). Divide them in the centre, so that one half is facing upwards and one half facing downwards. The outside of the posts should be skilfully covered all around with mud. If what supports the posts doesn’t burn, the posts themselves don’t burn. Skilfully cover the joins in the drains with mud, so nothing can leak out. The two sides should both be like this as the tunnel advances. Place charcoal and chaff in them where the lower end reaches the ground, but not so as to fill them completely. Charcoal and chaff are placed throughout the length of the pipes and are distributed equally to the left and right. At the internal openings of the tunnels, there should be furnaces which are like kilns. They should contain seven or eight balls of artemisia. The left and right pipes should both be like this. The kilns use four bellows. When the tunnels meet, use well-sweeps to clear away the intervening earth and urgently stir up the bellows to provide smoke against the enemy. Be certain to issue clear orders to those attending the bellows not to leave the furnace openings. Make linked wooden planks of a height and width commensurate with that of the tunnel. Order the tunnellers with the planks to go forward together. Holes are cut in the planks to allow them to hold spears. There are variations in the density and number to allow them to be used to save the pipes. When the tunnels meet, the planks are used to resist the enemy and the spears are used to protect the pipes. Don’t let the pipes become blocked. If the pipes are blocked, take up the planks and withdraw. If one blocked pipe is encountered, ream it out so smoke can pass. When smoke can pass, urgently work the bellows to produce smoke. If from within the tunnel, the sounds of tunnelling are heard to the left or right, the tunnel is immediately blocked at the front and not allowed to proceed further. If there is a joining with the enemy’s tunnel, the opening is blocked with brushwood and mud. In this way, the attack by tunnelling is defeated.

When the enemy reaches our city, it becomes a matter of great urgency. In carefully preparing [against] the enemy if tunnels are thought to exist, respond to the enemy [tunnels] by urgently tunnelling. While [our] tunnels are not yet in place, we must be careful not to pursue [the enemy].

In general, to defeat an attack by tunnelling, excavate a [defensive] tunnel every 20 bu, each tunnel being 10 chi high and 10 chi wide. As the tunnel advances forward, there should be a fall of 3 chi for every 1 bu. Every 10 bu of advancement, excavate transverse tunnels (yongxue) to the left and right, the height and width of each one being 10 chi.

Bury two ying so that the depth of the mouths of the ying is level with the ground within the wall. Use joined planks to cover each ying. Then, lying prostrate, listen [to them]. Every 5 bu have one well. For each tunnel, use tong (wood) or pine to make doors. Within the doors, place two caltrops, making the length of each equal to that of the doors. The doors should have [iron] rings. All around the doors of the tunnel, there should be a wall of stones 7 chi high. Add a parapet above it. Do not make steps but use a suspended ladder to go up or down, out or in. Prepare a furnace and bellows, the bellows being made of ox-hide. For the furnace have two bellows. Use well-sweeps weighing 100 jin with the very smallest not less than 40 jin. Use burning charcoal to put into the furnace, fill it and cover it so as not to allow smoke to escape. If the enemy is rapidly approaching our tunnel and their tunnel is higher or lower than ours so it does not enter our tunnel, then excavate at an incline and seek to connect with it.

When there is a confrontation with the enemy in the tunnel, in all cases oppose [them] but don’t pursue [them]. There should be alternation between fighting and feigning defeat to draw the enemy into one’s own tunnel. Then await the burning in the furnaces while hiding in concealed side tunnels like rats in their holes. Make a window with a locking cover through which the comings and goings within can be observed. On the wall outside each tunnel have a dog. When the dog barks, it is an indication that there are people.

Cut artemisia and firewood, [preparing bundles] 1 chi in length. Place them in the kilns or furnaces. First, make a pile of stones to screen off the kiln, [and then,] where it faces the tunnel, have joined planks.

Dig wells close enough to the wall[, having] one every 3 zhang. Survey the terrain outside [the wall] to establish where to place the wells, taking care not to make a mistake. If the wall is low and the tunnel high, it is difficult to detect the [enemy] tunnels. Within the wall, dig three or four wells, and inside each well place newly made ying so it is possible to lie prostrate and listen to them, thus gaining a detailed knowledge of where the [enemy] tunnels are situated. Make [counter-]tunnels to meet them. If the tunnels do, in fact, meet, prepare well-sweeps which must have strong timber for the handles. Use sharp axes to make them. Give the order for three strong men to use the well-sweeps to rush against the enemy and pour in more than 10 dan of foul material.

Quickly fill the centre of the furnace with brushwood and place seven or eight balls of artemisia on top. Use a basin to cover the mouth of the furnace, so as not to let the smoke leak out above. Bring the bellows next to the mouth and rapidly activate them.

Make a wen from cart wheels. Make one bundle of firewood, using a hempen rope steeped in mud to bind it around the middle. Suspend an iron chain directly facing the mouth of the enemy tunnel. The iron chain should be 3 zhang long with one end having a ring and the other end a hook.

[Make] ‘rat holes’ (shuxue) 7 chi 5 cun high with a width between the pillars on either side equal to 7 chi. [On the side walls,] have one pillar every 2 chi with a foundation stone placed beneath each pillar. Every two pillars should have a transverse piece of timber beneath them which connects them. The space under the timber should be filled with earth to support it. The circumference of each pillar should be 2½ wei. The supporting earth must be packed firmly, while the pillars themselves should not interconnect.

For every tunnel have two kilns and have tiles covering the doors of the tunnels. Have zhili (assistants) and sheren (assistants), one of each. Water must be placed [there]. Block up the doors of the tunnels with a pair of carriage wheels, making a wen which is coated with mud on its upper surface. The size of these is determined by the height and width of the tunnel. Order that they be placed 4 or 5 chi into the tunnel and secured with rope. When the enemy is engaged in the tunnel, turn [the pulleys] and lower the wen to obstruct [the enemy], and light the kilns. Put three balls of artemisia into the kilns. Then let the enemy rush forward and enter the tunnel. From a concealed position to one side, work the bellows and don’t leave the post. The lances used in the tunnels are made of iron and are 4½ chi long. There are [also] large [weapons] like iron battleaxes, as well as two kinds of lance with sharpened blades. After the tunnel has progressed 1 chi from its opening, the digging should incline downwards so the tunnel descends down towards the centre of the earth. Use lances that are 7 chi long. In the tunnel have encircling ropes for going up and down, two per tunnel.

Dig wells below the wall. Wait until the well is about to break through. Then, standing on a wooden plank, dig out one side. When that is complete, dig out the other side. Have two well-sweeps. At the sides, bury their posts and have hooks near the two ends. In all, have fifty people digging the tunnel with equal numbers of men and women. In the tunnel have implements for moving the earth, including six baskets, bound around the bottom with hempen rope, that can lift out the earth for distribution [around the opening of the tunnel]. When the tunnel is completed, seven men are left to defend it. Within the rampart create one large room within which the tunnelling equipment can be stored.

To make it difficult [for the enemy] to tunnel, collect up the wood and bricks scattered on the sides of the moat. [Inside the wall,] dig a trench as deep as the water level. To make it difficult for tunnels near at hand, prepare iron axes. An axe and its handle should be 4 chi long. Make enough for requirements. When the enemy has tunnels, you should also have tunnels to oppose them.

Make iron hooks 4 chi long – enough to meet requirements – and when the tunnels communicate, use them to hook the enemy tunnellers. Make short spears, short halberds, short crossbows and short arrows – enough to meet requirements – and when the tunnels communicate, use them for the fighting. For hacking the enemy, use a weapon with a bronze blade 5 chi in length. Make a hole in the head to fit a wooden handle, and above the place where the hand grips the handle have a carved indentation. Use this to oppose the enemy tunnellers.

Prepare and have ying (geophones) with a capacity of 30 dou or more. Bury them in the tunnels, [three] every zhang, to listen for the sounds of [enemy] tunnelling.

Make tunnels with a height of 8 chi and a width of 8 chi. Set up good supporting pillars and coat the outer surfaces of these with mud. Prepare furnaces and ox-hide bellows as well as pipes [for the transmission of smoke]. Each tunnel should have two pipes. Add a supply of rapidly combustible material such as artemisia, and when the tunnels connect, use this to provide smoke [against the enemy].

Make axes with metal blades and handles 3 chi in length. Provide four for each tunnel. Make baskets (lei), forty per tunnel, and hoes (shu), four per tunnel. Make axes of different kinds, saws, chisels and large hoes, sufficient for requirements. Make iron rails, four per tunnel.

Make medium-sized lu (shields) 10½ chi high and 4 chi wide. Make large lu for placing across the tunnels. Have a large quantity of hemp stalks sufficient to provide illumination for the tunnels.

Have a large quantity of vinegar so that when the enemy creates smoke, it can be used to relieve the eyes. Once the eyes are relieved, attention can again be directed to digging out the tunnel. Use basins to hold the vinegar and place these within the tunnels. [They should be] large basins not less than 4 dou [in capacity]. When there is smoke, bring the eyes near to the upper surface of the vinegar, using it to protect the eyes.