Having given this explanation of the origin of these three different defensive means, we shall now proceed to consider the value of each of them separately, under the heads of strong lines, strong positions, and entrenched camps resting on fortresses.
- Lines.—They are the worst kind of cordon war: the obstacle which they present to the aggressor is of no value at all unless they are defended by a powerful fire; in themselves they are simply worthless. But now the extent to which an army can furnish an effective fire is generally very small in proportion to the extent of country to be defended; the lines can, therefore, only be short, and consequently cover only a small extent of country, or the army will not be able really to defend the lines at all points. In consequence of this, the idea was started of not occupying all points in the line, but only watching them, and defending them by means of strong reserves, in the same way as a small river may be defended; but this procedure is in opposition to the nature of the means. If the natural obstacles of the ground are so great that such a method of defence could be applied, then the entrenchments were needless, and entail danger, for that method of defence is not local, and entrenchments are only suited to a strictly local defence; but if the entrenchments themselves are to be considered the chief impediments to approach, then we may easily conceive that an undefended line will not have much to say as an obstacle to approach. What is a twelve or fifteen feet ditch, and a rampart ten or twelve feet high, against the united efforts of many thousands, if these efforts are not hindered by the fire of an enemy? The consequence, therefore, is, that if such lines are short and tolerably well defended by troops, they can be turned; but if they are extensive, and not sufficiently occupied, they can be attacked in front, and taken without much difficulty.