CHAPTER XVIII.
Defence of Streams and Rivers
Streams and large rivers, in so far as we speak of their defence, belong, like mountains, to the category of strategic barriers. But they differ from mountains in two respects. The one concerns their relative, the other their absolute defence.
Like mountains, they strengthen the relative defence; but one of their peculiarities is, that they are like implements of hard and brittle metal, they either stand every blow without bending, or their defence breaks and then ends altogether. If the river is very large, and the other conditions are favourable, then the passage may be absolutely impossible. But if the defence of any river is forced at one point, then there cannot be, as in mountain warfare, a persistent defence afterwards; the affair is finished with that one act, unless that the river itself runs between mountains.
The other peculiarity of rivers in relation to war is, that in many cases they admit of very good, and in general of better combinations than mountains for a decisive battle.
Both again have this property in common, that they are dangerous and seductive objects which have often led to false measures, and placed generals in awkward situations. We shall notice these results in examining more closely the defence of rivers.
Although history is rather bare in examples of rivers defended with success, and therefore the opinion is justified that rivers and streams are no such formidable barriers as was once supposed, when an absolute defensive system seized all means of strengthening itself which the country offered, still the influence which they exercise to the advantage of the battle, as well as of the defence of a country, cannot be denied.
In order to look over the subject in a connected form, we shall specify the different points of view from which we propose to examine it.
First and foremost, the strategic results which streams and rivers produce through their defence, must be distinguished from the influence which they have on the defence of a country, even when not themselves specially defended.
Further, the defence itself may take three different forms:—
1. An absolute defence with the main body.