We have not yet noticed the frontiers of the state, nor said anything of the geometrical form of the whole system of fortresses, nor of the other geographical points in connection with their situation, because we regard the objects above mentioned as the most essential, and are of opinion that in many cases they alone are sufficient, particularly in small states. But, at the same time, other considerations may be admitted, and may be imperative in countries of a greater superficial extent, which either have a great many important towns and roads, or, on the contrary, are almost without any, which are either very rich, and, possessing already many fortresses, still want new ones, or those which, on the other hand, are very poor, and under the necessity of making a few answer, in short, in cases where the number of fortresses does not correspond with the number of important towns and roads which present themselves, being either considerably greater or less.
We shall now cast a glance at the nature of such other considerations.
The chief questions which remain relate to
1. The choice of the principal roads, if the two countries are connected by more roads than we wish to fortify.
2. Whether the fortresses are to be placed on the frontier only, or spread over the country. Or,
3. Whether they shall be distributed uniformly, or in groups.
4. Circumstances relating to the geography of the country to which it is necessary to pay attention.
A number of other points with respect to the geometrical form of the line of fortifications, such as whether they should be placed in a single line or in several lines, that is, whether they do more service when placed one behind another, or side by side in line with each other; whether they should be chequer-wise, or in a straight line; or whether they should take the form of a fortification itself, with salients and re-entering angles all these we look upon as empty subtilties, that is, considerations so insignificant, that, compared with the really important points, they are not worth notice; and we only mention them here because they are not merely treated of in many books, but also a great deal more is made of this rubbish than it is worth.
As regards the first question, in order to place it in a clearer light we shall merely instance the relation of the south of Germany to France, that is, to the upper Rhine. If, without reference to the number of separate states composing this district of country, we suppose it a whole which is to be fortified strategically, much doubt will arise, for a great number of very fine roads lead from the Rhine into the interior of Franconia, Bavaria and Austria. Certainly, towns are not wanting which surpass others in size and importance, as Nuremburg, Wurzburg, Ulm, Augsburg, and Munich; but if we are not disposed to fortify all, there is no alternative but to make a selection. If, further, in accordance with our view, the fortification of the greatest and wealthiest is held to be the principal thing, still it is not to be denied that, owing to the distance between Nuremburg and Munich, the first has a very different strategic signification from the second; and therefore it always remains to be considered whether it would not be better, in place of Nuremburg, to fortify some other place in the neighbourhood of Munich, even if the place is one of less importance in itself.
As concerns the decision in such cases, that is, answering the first question, we must refer to what has been said in the chapters on the general plan of defence, and on the choice of points of attack. Wherever the most natural point of attack is situated, there the defensive arrangements should be made by preference.