Liber III, Pars III — Qualiter aedificanda sunt castra aut civitates, ne par pugnam ab obsidentibus facilius devincantur. Cap. XX.

Liber III, Pars III — Qualiter aedificanda sunt castra aut civitates, ne par pugnam ab obsidentibus facilius devincantur. Cap. XX.

After we discussed field warfare and determined the nature of siege warfare, we will teach those besieging how they should besiege fortifications and camps, and how to conquer them. In this part, we want to determine about defensive warfare: that after we have taught the besiegers how they should invade those under siege, we want to teach those under siege how they should defend themselves against the besiegers. The first thing that prevents a besieged city from being conquered by the besiegers, and that allows those under siege to defend their fortifications more easily, is knowing how camps, cities, and other fortifications should be built so that they are not easily attacked. There are five things to consider in such construction: through which fortifications are stronger and harder to capture. First, fortifications are strengthened and are harder to attack based on the nature of the location. Second, the angularity of the walls. Third, the terrain. Fourth, the battlements. Fifth, from the fortifications. Indeed, the nature of the location makes cities and fortifications stronger if they are built on steep cliffs or in high, inaccessible places; or if they are surrounded by the sea, marshes, or rivers. Therefore, when fortifications are to be built to defend against external attacks and besiegers, the nature of the location must be considered so that they are built in such a way that they are stronger due to the very site. If there is no time to build new fortifications, and some fear the wrath of their lords or the Lord, fearing the future of the people, they wish to protect themselves in some fortification: if the opportunity arises, they should seek a fortification that is stronger due to the very nature of the location and harder to attack. Secondly, cities and fortifications are harder to attack due to the angularity of the walls. For if a fortification has angular walls, if attackers manage to approach the walls to conquer the fortification, the defenders can more easily protect themselves from them, and they strike the attackers less severely. Indeed, due to the angularity of the walls, attackers strike not only from the front but also from the rear, and as if from the back parts, they strike at the fortification. Thus, angular walls must be built so that the fortification can be defended more easily. The third factor that makes a fortification harder to capture is the presence of earthen walls or walls made of earth. In constructing a fortification, one must not only consider the quality of the site and the angularity of the walls, but also build two walls at a distance from each other around the fortification; within the space between these two walls, earth should be placed, which can be dug from the ditches that are to be made around the fortification, or earth can be brought in from elsewhere and placed in that intermediate space. This earth should also be compacted within that space so that it binds together and forms a kind of wall. It is also possible to make towers from earth if it is well compacted; therefore, it is not inappropriate to construct such walls from compressed earth. Indeed, the construction of such walls is valuable for defending the fortification, so that it is not overcome by siege engines. For if it is granted that the entire outer wall collapses under such machines, a wall made of earth would receive the blows of the machines almost without damage, because when a stone thrown by a machine strikes such a wall, the softness of the earth would yield, and it would absorb the stone as if it were constructed that way. It is indeed proven that walls made of compacted earth are less likely to be damaged by stone-throwing machines than other walls. Such a wall made of earth should indeed be thick, because then it will receive the stones thrown by machines almost without damage. The fourth thing that makes fortifications stronger is towers and battlements. For on the walls themselves, towers and battlements should be built so that the fortification can be defended more easily. Especially before any gate of the fortification, where there is fear that besiegers might approach, towers and battlements should be constructed, and before such a gate, a drawbridge should be placed, hanging on iron rings all around, also iron-clad, preventing the entrance of enemies and the outbreak of fire. For if the besiegers wanted to set fire to the gates of the fortification, the drawbridge in front of the gate will prevent them. Again, above the drawbridge, there should be a perforated wall that receives it, through which stones can be thrown, and water can be emitted to extinguish the fire, if it were to happen that it was placed there by the besiegers. The fifth thing that makes fortifications more inaccessible and stronger is the width and depth of the ditches, which should be filled with water if there is the means to do so. Thus, with these methods, fortifications are made more difficult to capture. Therefore, it must be considered from the beginning by those who wish to defend the fortifications against besiegers, that in those fortifications all these things or more from these should come together to ensure they are defended more easily.