THE term cordon is used to denote every defensive plan which is intended directly to cover a whole district of country by a line of posts in connection with each other. We say directly, for several corps of a great army posted in line with each other might protect a large district of country from invasion without forming a cordon; but then this protection would not be direct, but through the effect of combinations and movements.
It is evident at a glance that such a long defensive line as that must be, which is to cover an extensive district of country directly, can only have a very small degree of defensive stamina. Even when very large bodies of troops occupy the lines this would be the case if they were attacked by corresponding masses. The object of a cordon can therefore only be to resist a weak blow, whether that the weakness proceeds from a feeble will or the smallness of the force employed.
With this view the wall of China was built: a protection against the inroads of Tartars. This is the intention of all lines and frontier defences of the European States bordering on Asia and Turkey. Applied in this way the cordon system is neither absurd nor does it appear unsuitable to its purpose. Certainly it is not sufficient to stop all inroads, but it will make them more difficult and therefore of less frequent occurrence, and this is a point of considerable importance where relations subsist with people like those of Asia, whose passions and habits have a perpetual tendency to war.
Next to this class of cordons come the lines, which, in the wars of modern times have been formed between European States, such as the French lines on the Rhine and in the Netherlands. These were originally formed only with a view to protect a country against inroads made for the purpose of levying contributions or living at the expense of the enemy. They are, therefore, only intended to check minor operations, and consequently it is also meant that they should be defended by small bodies of troops. But, of course, in the event of the enemy's principal force taking its direction against these lines, the defender must also use his principal force in their defence, an event by no means conducive to the best defensive arrangements. On account of this disadvantage and because the protection against incursions in temporary war is quite a minor object, by which through the very existence of these lines an excessive expenditure of troops may easily be caused, their formation is looked upon in our day as a pernicious measure. The more power and energy thrown into the prosecution of the war the more useless and dangerous this means becomes.
Lastly, all very extended lines of outposts covering the quarters of an army and intended to offer a certain amount of resistance come under the head of cordons.
This defensive measure is chiefly designed as an impediment to raids, and other such minor expeditions directed against single cantonments, and for this purpose it may be quite sufficient if favoured by the country. Against an advance of the main body of the enemy the opposition offered can be only relative, that is, intended to gain time: but as this gain of time will be but inconsiderable in most cases, this object may be regarded as a very minor consideration in the establishment of these lines. The assembling and advance of the enemy's army itself can never take place so unobservedly that the defender gets his first information of it through his outposts; when such is the case he is much to be pitied.
Consequently, in this case also, the cordon is only intended to resist the attack of a weak force, and the object, therefore, in this and in the other two cases is not at variance with the means.
But that an army formed for the defence of a country should spread itself out in a long line of defensive posts opposite to the enemy, that it should disperse itself in a cordon form, seems to be so absurd that we must seek to discover the circumstances and motives which lead to and accompany such a proceeding.
Every position in a mountainous country, even if taken up with the view of a battle with the whole force united, is and must necessarily be more extended than a position in a level country. It may be because the aid of the ground augments very much the force of the resistance; it must be because a wider basis of retreat is required, as we have shown in the chapter on mountain defences. But if there is no near prospect of a battle, if it is probable that the enemy will remain in his position opposite to us for some time without undertaking anything unless tempted by some very favourable opportunity which may present itself (the usual state of things in most wars formerly), then it is also natural not to limit ourselves merely to the occupation of so much country as is absolutely necessary, but to hold as much right or left as is consistent with the security of the army, by which we obtain many advantages, as we shall presently show. In open countries with plenty of communications, this object may be effected to a greater extent than in mountains, through the principle of movement, and for that reason the extension and dispersion of the troops is less necessary in an open country; it would also be much more dangerous there on account of the inferior capability of resistance of each part.
But in mountains where all occupation of ground is more dependent on local defence, where relief cannot so soon be afforded to a point menaced, and where, when once the enemy has got possession of a point, it is more difficult to dislodge him by a force slightly superior—in mountains, under these circumstances, we shall always come to a form of position which, if not strictly speaking a cordon, still approaches very near to it, being a line of defensive posts. From such a disposition, consisting of several detached posts, to the cordon system, there is still certainly a considerable step, but it is one which generals, nevertheless, often take without being aware of it, being drawn on from one step to another. First, the covering and the possession of the country is the object of the dispersion; afterwards it is the security of the army itself. Every commander of a post calculates the advantage which may be derived from this or that point connected with the approach to his position on the right or the left, and thus the whole progresses insensibly from one degree of subdivision to another.
A cordon war, therefore, carried on by the principal force of an army, is not to be considered a form of war designedly chosen with a view to stopping every blow which the enemy's forces might attempt, but a situation which the army is drawn into in the pursuit of a very different object, namely, the holding and covering the country against an enemy who has no decisive undertaking in view. Such a situation must always be looked upon as a mistake; and the motives through which generals have been lured by degrees into allowing one small post after another, are contemptible in connection with the object of a large army; this point of view shows, at all events, the possibility of such a mistake. That it is really an error, namely, a mistaken appreciation of our own position, and that of the enemy is sometimes not observed, and it is spoken of as an erroneous system. But this same system, when it is pursued with advantage, or, at all events, without causing damage, is quietly approved. Every one praises the faultless campaigns of Prince Henry in the Seven Years' War, because they have been pronounced so by the king, although these campaigns exhibit the most decided and most incomprehensible examples of chains of posts so extended that they may just with as much propriety be called cordons as any that ever were. We may completely justify these positions by saying, the prince knew his opponent; he knew that he had no enterprises of a decisive character to apprehend from that quarter, and as the object of his position besides was to occupy always as much territory as possible, he therefore carried out that object as far as circumstances in any way permitted. If the prince had once been unfortunate with one of these cobwebs, and had met with a severe loss, we should not say that he had pursued a faulty system of warfare, but that he had been mistaken about a measure and had applied it to a case to which it was not suited.
While we thus seek to explain how the cordon system, as it is called, may be resorted to by the principal force in a theatre in war, and how it may even be a judicious and useful measure, and, therefore, far from being an absurdity, we must, at the same time, acknowledge that there appear to have been instances where generals or their staff have overlooked the real meaning or object of a cordon system, and assumed its relative value to be a general one; conceiving it to be really suited to afford protection against every kind of attack, instances, therefore, where there was no mistaken application of the measure but a complete misunderstanding of its nature; we shall further allow that this very absurdity amongst others seems to have taken place in the defence of the Vosges by the Austrian and Prussian armies in 1793 and 1794.