Liber III, Pars III — Quod utile est in exercitu facere fossas, et construere castra, et qualiter castra sunt construenda, et quae sunt attendenda in constructione castrorum. Cap. VIII.

Liber III, Pars III — Quod utile est in exercitu facere fossas, et construere castra, et qualiter castra sunt construenda, et quae sunt attendenda in constructione castrorum. Cap. VIII.

Military matters seem to be among the more dangerous activities, so great care must be taken with them. In such matters, one cannot be too careful. In battle, one must choose to exercise greater diligence than the circumstances of the conflict require. For Vegetius quotes Cato, saying that in other matters, if there is any error, it can be corrected later. However, mistakes in warfare cannot be corrected; punishment for errors follows immediately, because those who fight carelessly and imprudently either perish quickly or become so timid in flight that they hardly dare to engage in battle against their victorious foes. Therefore, if one must be exceedingly cautious in warfare, nothing should be overlooked that could be beneficial to the army in any situation, lest it be defeated by the enemy. It often happens, both during the day and at night, that when an army is without trenches and camps, and does not believe the enemy is nearby, it is caught off guard by approaching foes and is routed. Therefore, once the army has completed its daily routine, if it wishes to camp somewhere or extend its stay, it must be prepared to dig trenches and erect some fortifications as if they were camps, because nothing is found to be as beneficial or necessary in war as properly constructed fortifications and well-established camps, so that the entire army remains secure within the camp's boundaries, regardless of when or from where the enemy may attack. The army must carry appropriate fortifications with it, so that when it wants to camp, it seems to carry a fortified city with it. It is useful to make trenches and build camps around the army; it remains to show how such fortifications and camps should be constructed. For if the enemies are absent, it is easy to dig trenches around the army, to erect fortifications, and to build camps, but if the adversaries are present, it is more difficult to fortify the camps. In such a case, there are two necessities: namely, to resist the enemies and to build camps. In such an event, according to the wisdom of the wise, the army must be divided, so that all the cavalry and one part of the infantry should be arranged in battle line to repel the enemy's attack; the remaining part of the infantry that can suffice for the rapid construction of the camps should quickly build the camps. Moreover, there should always be some overseers appointed for the construction of the camps and the digging of the trenches, who will urge the negligent and instruct each one on what they should do. It has been shown that it is useful to build camps and how they should be constructed even in the presence of enemies; the remaining task is to declare what should be considered in the construction of the camps. In digging trenches and in constructing camps, there are three things to consider regarding the space where the army is to be positioned. That is, the location, shape; and the method of fortification. Regarding the location (as far as the present situation is concerned), there are four things to consider. First, there should be a supply of water available. And other necessities for the army. Second, there should not be a nearby hill from which the army could be attacked. Third, the space must be considered so that it accommodates the number of soldiers; the area for fortifications should not exceed what is required for such a multitude, nor should it be so small that the army is forced to be cramped and crowded. Fourth, if it is necessary to delay the army in that location, and if there is an opportunity, the healthiness of the air should be considered. For in an army, not only must the wounds from enemies be avoided, but also, as opportunities arise, the dangers of diseases must be avoided. Therefore, having established what needs to be considered regarding the location of the camp, it must be declared what its shape should be. Vegetius seems to suggest that the fortifications and trenches around the army should have a quadrilateral or oblong shape. However, since a circular shape is the most capacious, it is preferable to construct fortifications in a circular form or in the shape of many angles; because if there is great fear of an enemy attack, it would be necessary to create trenches with many angles, as this is more suitable for defense, as will be explained below. Such a shape is therefore better for the construction of camps, unless the location's site prevents it. For sometimes it happens that the site cannot accommodate such a shape. In such a case, semicircular, triangular, or square camps should be constructed, or any other shape that the situation and suitability require. The main gate should be built on the side facing the enemies, or where the army is protected. There should also be signs placed in the camps to frighten the enemies: and also for this purpose, so that if any of the army happen to stray from the camp, they can see the signs and know better how to return to the camp. Now that we've discussed what needs to be considered regarding the construction of fortifications, we must see what kind of fortification method should be followed. If the army intends to stay there for a long time, stronger fortifications should be chosen, and wider ditches should be dug. But if the army only wants to spend the night there, or if it will stay for a short time, it shouldn't require such extensive fortifications. Vegetius states the dimensions and type of ditches, saying that if there isn't a great threat from the enemy, the ditch should be nine feet wide and seven feet deep. However, if a stronger enemy force threatens, the ditch should be made wider and deeper, so that it is twelve feet wide and nine feet deep. It should be noted that if the ditch is nine feet deep, the earth thrown up over the ditch will raise it by about four feet, making the total depth about thirteen feet; thus, the ditch should be placed in front of the enemy, and the earth should be thrown to the inside where the army will be positioned. In that area, stakes, wood, and other fortifications should be set up, which the army must carry with them. Thus, once the fortifications are established and the ditches are dug, the army will be able to remain there safely.