Seventh Book

SEVENTH BOOK
You ought to know that towns and fortresses can be strong either by nature or industry. Those are strong by nature which are surrounded by rivers or marshes, as is Mantua or Ferrara, or those situated on a rock or sloping mountain, as Monaco and San Leo; for those situated on mountains which are not difficult to climb, today are ((with respect to caves and artillery)) very weak. And, therefore, very often today a plain is sought on which to build (a city) to make it strong by industry. The first industry is, to make the walls twisted and full of turned recesses; which pattern results in the enemy not being able to approach them, as they will be able to be attacked easily not only from the front, but on the flanks. If the walls are made too high, they are excessively exposed to the blows of the artillery; if they are made too low, they are very easily scaled. If you dig ditches (moats) in front of them to make it difficult (to employ) ladders, if it should happen that the enemy fills them ((which a large army can do easily)) the wall becomes prey to the enemy. I believe, therefore, ((subject to a better judgement)) that if you want to make provision against both evils the wall ought to be made high, with the ditches inside and not outside. This is the strongest way to build that is possible, for it protects you from artillery and ladders, and does not give the enemy the faculty of filling the ditches. The wall, therefore, ought to be as high as occurs to you, and not less than three arm lengths wide, to make it more difficult to be ruined. It ought to have towers placed at intervals of two hundred arm lengths. The ditch inside ought to be at least thirty arm lengths wide and twelve deep, and all the earth that is excavated in making the ditch is thrown toward the city, and is sustained by a wall that is part of the base of the ditch, and extends again as much above the ground, as that a man may take cover behind it: which has the effect of making the depth of the ditch greater. In the base of the ditch, every two hundred arm lengths, there should be a matted enclosure, which with the artillery, causes injury to anyone who should descend into it. The heavy artillery which defends the city, are placed behind the wall enclosing the ditch; for to defend the wall from the front, as it is high, it is not possible to use conveniently anything else other than small or middle sized guns. If the enemy comes to scale your wall, the height of the first wall easily protects you. If he comes with artillery, he must first batter down the first wall: but once it is battered down, because the nature of all batterings is to cause the wall to fall toward the battered side, the ruin of the wall will result ((since it does not find a ditch which receives and hides it)) in doubling the depth of the ditch, so that it is not possible for you to pass on further as you will find a ruin that holds you back and a ditch which will impede you, and from the