Discourses on Fortifications

As can be seen with shot B in bastion C, and with shot D in bastion E. If one wishes to make the orecchione follow the straight line of the shoulder so that all the mouths of the embrasures near it are hidden, just as those near the shoulders in the higher plazas are, one must note that since the defenders must (as is reasonable) uncover the lowest part of the exterior angle of the bastion, the aforementioned embrasures will nevertheless always be exposed from the outside due to the scarpa sloping wall base.

Let no one believe they can cover these embrasures so that they are not somewhat seen while giving a slope to the faces of the bastions and wishing to defend their lower parts, unless one makes the embrasures hide so far under the shoulders or orecchioni that they cannot uncover more than half the length of the bastion faces. If this were done, besides the fact that the enemies walking through the ditch would only have to watch out for the embrasures that are very visible, they could also, before they reach the mark where they would be exposed, arrange themselves in such a way that little trouble would be given to them by the defenders, especially when a good part of the faces of said bastions is ruined.

To conclude, therefore, I say that to cover the said embrasures it will be necessary to do one of three things: either make the faces of the bastions without a slope, or make the orecchioni on the inside have the slope in reverse (that is, upside down) from that of the bastion face, or ensure that the embrasures cannot, as I said above, uncover the entire length of the bastion faces. Of these three things, I would consider it more beneficial not to give a slope to the faces of the bastions, nor to the orecchioni or shoulders on the inside, so that all the embrasures of their flanks could defend the faces of the opposite bastions or other buildings of similar intention with less trouble. This could not be done by all the aforementioned embrasures if the orecchione is given a reverse slope on the inside.

But of this second method, I would consider it even worse to cover the nearby embrasures so much with the shoulders and orecchioni that they cannot uncover more than half, or a little more, of the length of the bastion faces. This is because, as I said above, I could not harass the enemy coming under a bastion face, and the other embrasures, remaining few and quite exposed, would be very disturbed in performing their duty due to the aforementioned slope of the bastion faces.

Furthermore, it truly seems to me that one must take the greatest care in making these types of bastions everywhere and at all times, drawn from some part of the main curtain. If one gains the benefit I mentioned, one remains more subjected to other damages of no light weight, particularly when the bastions or other buildings of similar intention become acute. That acuteness increases the slope that is usually given to the enclosures, that is, at their exterior angles. Thus, because of the slope and the weakness of those angles, which could be easily ruined, the enemies could more easily impede the flanks in their duty.

Moreover, the longer the faces of such buildings are, the more the enemy could remain unvisited by the aforementioned flanks, though only in a less deep battery made at the extreme part of the bastion. But in proportion to the circuit, the building will always have little interior plaza. For the defense of such a space, due to the length of said faces, more people will be required than would be necessary for a more capable plaza, without the advantage of a circuit. Such a building would be less powerful due to its acuteness, and less able to be defended by the flanks, which, for the reasons mentioned, would be more impeded by the enemies.

Not only must all figures that produce acute, right, or slightly obtuse angles be avoided for the aforementioned effects, but also because with the same circumference of enclosure, one encloses less plaza. Therefore, quadrangular fortresses are not made when it is possible to do otherwise, nor are very large flanks made in them, nor are they made very close together, although this is also avoided to make the flanks less exposed to batteries and because of the increased expense in both making and maintaining them. Because, although the multiplication of angles in circular figures causes perfection, I do not believe that any person of judgment, provided the bastions are not acute, will set out to make a figure contain more angles just to make the bastions obtuse. It will be enough, to avoid acuteness, to leave the square and pentagonal shapes—even if they were of equal sides and angles—and make it of six angles.

Now, if one multiplies two angles to avoid acuteness, who would do that which, having only regard for multiplication, sets out to make acute angles that could have been obtuse? One must also consider that fortresses are not always made or cannot always be made entirely anew, giving them the desired shape, or without using some part of the old. It will not be out of place to note the difference between the two following bastions: although they are made with equal angles, the bastion G is nonetheless more perfect in its exterior angle, or to speak better, less wretched than the angle of bastion H, and it has flanks one-third longer. Bastion H, because its faces are directed toward the third part of the curtain I, having a shorter flank, is more imperfect in the exterior angle. Thus, when the bastion does not become too acute, it would not be a bad thing to make the flanks so large, as buildings would be more powerful due to their size and because the exterior angles would be much better, and the defenses could come from so far out that great trouble would be given to those who wanted to stand under a battery. And when the site forced me to make the bastions acute, I would always consider it better to err in the acuteness of bastion G than of the other.