Tuesday 29 December 2020

Tuesday’s Serial: “On War” by General Carl von Clausewitz (Translated into English by Colonel J.J. Graham) – XXXI

CHAPTER XX - A. Defence of Swamps

Very large wide swamps, such as the Bourtang Moor in North Germany, are so uncommon that it is not worth while to lose time over them; but we must not forget that certain lowlands and marshy banks of small rivers are more common, and form very considerable obstacles of ground which may be, and often have been, used for defensive purposes.

Measures for their defence are certainly very like those for the defence of rivers, at the same time there are some peculiarties to be specially noticed. The first and principal one is, that a marsh which except on the causeway is impracticable for infantry is much more difficult to cross than any river; for, in the first place, a causeway is not so soon built as a bridge; secondly, there are no means at hand by which the troops to cover the construction of the dyke or causeway can be sent across. No one would begin to build a bridge without using some of the boats to send over an advanced guard in the first instance; but in the case of a morass no similar assistance can be employed; the easiest way to make a crossing for infantry over a morass is by means of planks, but when the morass is of some width, this is a much more tedious process than the crossing of the first boats on a river. If now, besides, there is in the middle of the morass a river which cannot be passed without a bridge, the crossing of the first detachment of troops becomes a still more difficult affair, for although single passengers may get across on boards, the heavy material required for bridge building cannot be so transported. This difficulty on many occasions may be insurmountable.

A second peculiarity of a swamp is, that the means used to cross cannot be completely removed like those, used for passing a river; bridges may be broken, or so completely destroyed that they can never be used again; the most that can be done with dykes is to cut them, which is not doing much. If there is a river in the middle, the bridge can of course be taken away, but the whole passage will not by that means be destroyed in the same degree as that of a large river by the destruction of a bridge. The natural consequence is that dykes which exist must always be occupied in force and strenuously defended if we desire to derive any general advantage from the morass.

On the one hand, therefore, we are compelled to adopt a local defence, and on the other, such a defence is favoured by the difficulty of passing at other parts. From these two peculiarities the result is, that the defence of a swamp must be more local and passive than that of a river.

It follows from this that we must be stronger in a relative degree than in the direct defence of a river, consequently that the line of defence must not be of great length, especially in cultivated countries, where the number of passages, even under the most favourable circumstances for defence, is still very great.

In this respect, therefore, swamps are inferior to great rivers, and this is a point of great importance, for all local defence is illusory and dangerous to an extreme. But if we reflect that such swamps and low grounds generally have a breadth with which that of the largest rivers in Europe bears no comparison, and that consequently a post stationed for the defence of a passage is never in danger of being overpowered by the fire from the other side, that the effects of its own fire over a long narrow dyke is greatly increased, and that the time required to pass such a defile, perhaps a quarter or half a mile long, is much longer than would suffice to pass an ordinary bridge: if we consider all this, we must admit that such low lands and morasses, if means of crossing are not too numerous, belong to the strongest lines of defence which can be formed.

An indirect defence, such as we made ourselves acquainted with in the case of streams and rivers, in which obstacles of ground are made use of to bring on a great battle under advantageous circumstances, is generally quite as applicable to morasses.

The third method of a river-defence by means of a position on the enemy’s side would be too hazardous on account of the toilsome nature of the crossing.

It is extremely dangerous to venture on the defence of such morasses, soft meadows, bogs, etc., as are not quite impassable beyond the dykes. One single line of crossing discovered by the enemy is sufficient to pierce the whole line of defence which, in case of a serious resistance, is always attended with great loss to the defender.

 

B. Inundations

Now we have still to consider inundations. As defensive means and also as phenomena in the natural world they have unquestionably the nearest resemblance to morasses.

They are not common certainly; perhaps Holland is the only country in Europe where they constitute a phenomenon which makes them worth notice in connection with our object; but just that country, on account of the remarkable campaigns of 1672 and 1787, as well as on account of its important relation in itself to both France and Germany, obliges us to devote some consideration to this matter.

The character of these Dutch inundations differs from ordinary swampy and impassable wet low lands in the following respects:

 

1. The soil itself is dry and consists either of dry meadows or of cultivated fields.

2. For purposes of irrigation or of drainage, a number of small ditches of greater or loss depth and breadth intersect the country in such a way that they may be seen running in lines in parallel directions.

3. Larger canals, inclosed by dykes and intended for irrigation, drainage, and transit of vessels, run through the country in all possible directions and are of such a size that they can only be passed on bridges.

4. The level of the ground throughout the whole district subject to inundation, lies perceptibly under the level of the sea, therefore, of course, under that of the canals.

5. The consequence of this is, that by means of cutting the dams, closing and opening the sluices, the whole country can be laid under water, so that there are no dry roads except on the tops of the dykes, all others being either entirely under water or, at least, so soaked that they become no longer fit for use. Now, if even the inundation is only three or four feet deep, so that, perhaps, for short distances it might be waded through, still even that is made impossible on account of the smaller ditches mentioned under No. 2, which are not visible. It is only where these ditches have a corresponding direction, so that we can move between two of them without crossing either, that the inundation does not constitute in effect an absolute bar to all communication. It is easy to conceive that this exception to the general obstruction can only be for short distances, and, therefore, can only be used for tactical purposes of an entirely special character.

 

From all this we deduce

 

1. That the assailant’s means of moving are limited to a more or less small number of practicable lines, which run along very narrow dykes, and usually have a wet ditch on the right and left, consequently form very long defiles.

2. That every defensive preparation upon such a dam may be easily strengthened to such a degree as to become impregnable.

3. But that, because the defensive is so hemmed in, he must confine himself to the most passive resistance as respects each isolated point, and consequently must look for his safety entirely from passive resistance.

4. That in such a country it is not a system of a single defensive line, closing the country like a simple barrier, but that as in every direction the same obstacle to movement exists, and the same security for flanks may be found, new posts may incessantly be formed, and in this manner any portion of the first defensive line, if lost, may be replaced by a new piece. We may say that the number of combinations here, like those on a chessboard, are infinite.

5. But while this general condition of a country is only conceivable along with the supposition of a high degree of cultivation and a dense population, it follows of itself that the number of passages, and therefore the number of posts required or their defence, must be very great in comparison to other strategetic dispositions; from which again we have, as a consequence, that such a defensive line must not be long.

 

The principal line of defence in Holland is from Naarden on the Zuyder Zee (the greater part of the way behind the Vecht), to Gorcum on the Waal, that is properly to the Biesbosch, its extent being about eight miles. For the defence of this line a force of 25,000 to 30,000 was employed in 1672, and again in 1787. If we could reckon with certainty upon an invincible resistance, the results would certainly be very great, at least for the provinces of Holland lying behind that line.

In 1672 the line actually withstood very superior forces led by great generals, first Condé, and afterwards Luxembourg, who had under their command 40,000 to 50,000 men, and yet would not assault, preferring to wait for the winter, which did not prove severe enough. On the other hand, the resistance which was made on this first line in 1787 amounted to nothing, and even that which was made by a second line much shorter, between the Zuyder Zee and the lake of Haarlem, although somewhat more effective, was overcome by the Duke of Brunswick in one day, through a very skilful tactical disposition well adapted to the locality, and this although the Prussian force actually engaged in the attack was little, if at all, superior in numbers to the troops guarding the lines.

The different result in the two cases is to be attributed to the difference in the supreme command. In the year 1672 the Dutch were surprised by Louis XIV., while everything was on a peace establishment, in which, as is well known, there breathed very little military spirit as far as concerned land forces. For that reason the greater number of the fortresses were deficient in all articles of material and equipment, garrisoned only by weak bodies of hired troops, and defended by governors who were either native-born incapables, or treacherous foreigners. Thus all the Brandenburg fortresses on the Rhine, garrisoned by Dutch, as well as all their own places situated to the east of the line of defence above described, except Groningen, very soon fell into the hands of the French, and for the most part without any real defence. And in the conquest of this great number of places consisted the chief exertions of the French army, 150,000 strong, at that time.

But when, after the murder of the brothers De Witt, in August 1672, the Prince of Orange came to the head of affairs, bringing unity to the measures for national defence, there was still time to close the defensive line above-mentioned, and all the measures then adopted harmonised so well with each other that neither Condé nor Luxembourg, who commanded the French armies left in Holland after the departure of the two armies under Turenne and Louis in person, would venture to attempt anything against the separate posts.

In the year 1787 all was different. It was not the Republic of seven united provinces, but only the province of Holland which had to resist the invasion. The conquest of all the fortresses, which had been the principal object in 1672, was therefore not the question; the defence was confined at once to the line we have described. But the assailant this time, instead of 150,000 men, had only 25,000, and was no mighty sovereign of a great country adjoining Holland, but the subordinate general of a distant prince, himself by no means independent in many respects. The people in Holland, like those everywhere else at that time, were divided into two parties, but the republican spirit in Holland was decidedly predominant, and had at the same time attained even to a kind of enthusiastic excitement. Under these circumstances the resistance in the year 1787 ought to have ensured at least as great results as that of 1672. But there was one important difference, which is, that in the year 1787 unity of command was entirely wanting. What in 1672 had been left to the wise, skilful, and energetic guidance of the Prince of Orange, was entrusted to a so called Defence Commission in 1787, which although it included in its number men of energy, was not in a position to infuse into its work the requisite unity of measures, and to inspire others with that confidence which was wanted to prevent the whole instrument from proving imperfect and inefficient in use.

We have dwelt for a moment on this example, in order to give more distinctness to the conception of this defensive measure, and at the same time to show the difference in the effects produced, according as more or less unity and sequence prevail in the direction of the whole.

Although the organisation and method of defence of such a defensive line are tactical subjects, still, in connection with the latter, which is the nearest allied to strategy, we cannot omit to make an observation to which the campaign of 1787 gives occasion.

We think, namely, that however passive the defence must naturally be at each point in a line of this kind, still an offensive action from some one point of the line is not impossible, and may not be unproductive of good results if the enemy, as was the case in 1787, is not decidedly very superior. For although such an attack must be executed by means of dykes, and on that account cannot certainly have the advantage of much freedom of movement or of any great impulsive force, nevertheless, it is impossible for the offensive side to occupy all the dykes and roads which he does not require for his own purposes, and therefore the defensive with his better knowledge of the country, and being in possession of the strong points, should be able by some of the unoccupied dykes to effect a real flank attack against the columns of the assailant, or to cut them off from their sources of supply. If now, on the other hand, we reflect for a moment on the constrained position in which the assailant is placed, how much more dependent he is on his communications than in almost any other conceivable case, we may well imagine that every sally on the part of the defensive side which has the remotest possibility of success must at once as a demonstration be most effective. We doubt very much if the prudent and cautious duke of Brunswick would have ventured to approach Amsterdam if the Dutch had only made such a demonstration, from Utrecht for instance.

 

 

CHAPTER XXI - Defence of Forests

Above all things we must distinguish thick tangled and impassable forests from extensive woods under a certain degree of culture, which are partly quite clear, partly intersected by numerous roads.

Whenever the object is to form a defensive line, the latter should be left in rear or avoided as much as possible. The defensive requires more than the assailant to see clearly round him, partly because, as a rule, he is the weaker, partly because the natural advantages of his position cause him to develop his plans later than the assailant. If he should place a woody district before him he would be fighting like a blind man against one with his eyesight. If he should place himself in the middle of the wood then both would be blind, but that equality of condition is just what would not answer the natural requirements of the defender.

Such a wooded country can therefore not be brought into any favourable connection with the defensive except it is kept in rear of the defender’s army, so as to conceal from the enemy all that takes place behind that army, and at the same time to be available as an assistance to cover and facilitate the retreat.

At present we only speak of forests in level country, for where the decided mountain character enters into combination, its influence becomes predominant over tactical and strategic measures, and we have already treated of those subjects elsewhere.

But impassable forests, that is, such as can only be traversed on certain roads, afford advantages in an indirect defence similar to those which the defence derives from mountains for bringing on a battle under favourable circumstances; the army can await the enemy behind the wood in a more or less concentrated position with a view to falling on him the moment he debouches from the road defiles. Such a forest resembles mountain in its effects more than a river: for it affords, it is true, only one very long and difficult defile, but it is in respect to the retreat rather advantageous than otherwise.

But a direct defence of forests, let them be ever so impracticable, is a very hazardous piece of work for even the thinnest chain of outposts; for abattis are only imaginary barriers, and no wood is so completely impassable that it cannot be penetrated in a hundred places by small detachments, and these, in their relation to a chain of defensive posts, may be likened to the first drops of water which ooze through a roof and are soon followed by a general rush of water.

Much more important is the influence of great forests of every kind in connection with the arming of a nation; they are undoubtedly the true element for such levies; if, therefore, the strategic plan of defence can be so arranged that the enemy’s communications pass through great forests, then, by that means, another mighty lever is brought into use in support of the work of defence.

 

 

CHAPTER XX - The Cordon

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.

 

 

CHAPTER XXIII - Key to the Country

There is no theoretical idea in the art of war which has played such a part in criticism as that we are now entering upon. It is the “great war steed” in all accounts of battles and campaigns; the most frequent point of view in all arguments, and one of those fragments of scientific form with which critics make a show of learning. And yet the conception embodied in it has never yet been established, nor has it ever been clearly explained.

We shall try to ascertain its real meaning, and then see how far it can be made available for practical use.

We treat of it here because the defence of mountains, river defences, as well as the conceptions of strong and entrenched camps with which it closely connects itself, required to have precedence.

The indefinite confused conception which is concealed behind this ancient military metaphor has sometimes signified the most exposed part of a country at other times the strongest.

If there is any spot without the possession of which no one dare venture to penetrate into an enemy’s country that may, with propriety, be called the key of that country. But this simple, though certainly at the same time also, barren notion has not satisfied theorists, and they have amplified it, and under the term key of a country imagined points which decide upon the possession of the whole country.

When the Russians wanted to advance into the Crimean peninsula, they were obliged to make themselves masters of the isthmus of Perekop and its lines, not so much to gain an entrance generally—for Lascy turned it twice (1737 and 1738)—but to be able to establish themselves with tolerable security in the Crimea. That is very simple, but we gain very little in this through the conception of a key-point. But if it might be said, Whoever has possession of the district of Langres commands all France as far as Paris—that is to say, it only rests with himself to take possession—that is plainly a very different thing, something of much higher importance. According to the first kind of conception the possession of the country cannot be thought of without the possession of the point which we have called key; that is a thing which is intelligible to the most ordinary capacity: but according to the second kind of conception, the possession of the point which we have called key, cannot be imagined without the possession of the country following as a necessary consequence; that is plainly, something marvellous, common sense is no longer sufficient to grasp this, the magic of the occult sciences must be called into requisition. This cabala came into existence in works published fifty years ago, and reached its zenith at the end of the last century; and notwithstanding the irresistible force, certainty and distinctness with which Buonaparte’s method of conducting war carried conviction generally, this cabala has, nevertheless, still managed, we say, to spin out the thread of its tenacious existence through the medium of books.

(Setting aside for a moment our conception of the key-point) it is self-evident that in every country there are points of commanding importance, where several roads meet, where our means of subsistence may be conveniently collected, which have the advantage of being centrally situated with reference to other important points, the possession of which in short meets many requirements and affords many advantages. Now, if generals wishing to express the importance of such a point by one word have called it the key of the land, it would be pedantic affectation to take offence at their using that term; on the contrary we should rather say the term is very expressive and pleasing. But if we try to convert this mere flower of speech into the germ of a system branching out like a tree into many ramifications, common sense rises in opposition, and demands that the expression should be restricted to its true value.

In order to develop a system out of the expression, it was necessary to resort to something more distinct and absolute than the practical, but certainly very indefinite, meaning attaching to the term in the narrations of generals when speaking of their military enterprises. And from amongst all its various relations, that of high ground was chosen.

Where a road traverses a mountain ridge, we thank heaven when we get to the top and have only to descend. This feeling so natural to a single traveller is still more so in the case of an army All difficulties seem to be overcome, and so they are indeed in most instances; we find that the descent is easy, and we are conscious of a kind of feeling of superiority over any one who would stop us; we have an extensive view over the country, and command it with a look beforehand. Thus the highest point on a road over a mountain is always considered to possess a decisive importance, and it does in fact in the majority of cases, but by no means in all. Such points are very often described in the despatches of generals by the name of key-points; but certainly again in a somewhat different and generally in a more restricted sense. This idea has been the starting point of a false theory (of which, perhaps, Lloyd may be regarded as the founder); and on this account, elevated points from which several roads descend into the adjacent country, came to be regarded as the keypoints of the country—as points which command the country. It was natural that this view should amalgamate itself with one very nearly connected with it, that of a systematic defence of mountains, and that the matter should thus be driven still further into the regions of the illusory; added to which many tactical elements connected with the defence of mountains came into play, and thus the idea of the highest point in the road was soon abandoned, and the highest point generally of the whole mountain system, that is the point of the watershed, was substituted for it as the key of the country.

Now just at that time, that is the latter half of the preceding century, more definite ideas on the forms given to the surface of the earth through aqueous action became current; thus natural science lent a hand to the theory of war by this geological system, and then every barrier of practical truth was broken through, and reasoning floated in the illusory system of a geological analogy. In consequence of this, about the end of the eighteenth century we heard, or rather we read, of nothing but the sources of the Rhine and Danube. It is true that this nuisance prevailed mostly in books, for only a small portion of book wisdom ever reaches the real world, and the more foolish a theory the less it will attain to practice; but this of which we are now speaking has not been unproductive of injury to Germany by its practical effects, therefore we are not fighting with a windmill, in proof of which we shall quote two examples; first, the important but very scientific campaigns of the Prussian army, 1793 and 1794 in the Vosges, the theoretical key to which will be found in the works of Gravert and Massenbach; secondly, the campaign of 1814, when, on the principle of the same theory, an army of 200,000 men was led by the nose through Switzerland on to the plateau of Langres as it is called.

But a high point in a country from which all its waters flow, is generally nothing more than a high point; and all that in exaggeration and false application of ideas, true in themselves, was written at the end of the eighteenth and commencement of the nineteenth centuries, about its influence on military events, is completely imaginary. If the Rhine and Danube and all the six rivers of Germany had their common source on the top of one mountain, that mountain would not on that account have any claim to any greater military value than being suited for the position of a trigonometrical point. For a signal tower it would be less useful, still less so for a vidette, and for a whole army worth just nothing at all.

To seek for a key-position therefore in the so called key country, that is where the different branches of the mountains diverge from a common point, and at the highest source of its waters, is merely an idea in books, which is overthrown by nature itself, because nature does not make the ridges and valleys so easy to descend as is assumed by the hitherto so called theory of ground, but distributes peaks and gorges, in the most irregular manner, and not unfrequently the lowest water level is surrounded by the loftiest masses of mountain. If any one questions military history on the subject, he will soon convince himself that the leading geological points of a country exercise very little regular influence on the use of the country for the purposes of war, and that little is so over-balanced by other local circumstances, and other requirements, that a line of positions may often run quite close to one of the points we are discussing without having been in any way attracted there by that point.

We have only dwelt so long upon this false idea because a whole—and very pretentious—system has built itself upon it. We now leave it, and turn back to our own views.

We say, then, that if the expression, key-position, is to represent an independent conception in strategy, it must only be that of a locality the possession of which is indispensable before daring to enter the enemy’s country. But if we choose to designate by that term every convenient point of entrance to a country, or every advantageous central point in the country, then the term loses its real meaning (that is, its value), and denotes something which may be found anywhere more or less. It then becomes a mere pleasing figure of speech.

But positions such as the term conveys to our mind are very rarely indeed to be found. In general, the best key to the country lies in the enemy’s army; and when the idea of country predominates over that of the armed force, some very specially advantageous circumstances must prevail. These, according to our opinion, may be recognised by their tending to two principal results: first, that the force occupying the position, through the help of the ground, obtains extraordinary capability of tactical resistance; second, that the enemy’s lines of communication can be sooner effectively threatened from this position than he can threaten ours.

 

 

CHAPTER XXIV - Operating Against a Flank

We need hardly observe that we speak of the strategic flank, that is, a side of the theatre of war, and that the attack from one side in battle, or the tactical movement against a flank, must not be confounded with it; and even in cases in which the strategic operation against a flank, in its last stage, ends in the tactical operation, they can quite easily be kept separate, because the one never follows necessarily out of the other.

These flanking movements, and the flanking positions connected with them, belong also to the mere useless pageantry of theory, which is seldom met with in actual war. Not that the means itself is either ineffectual or illusory, but because both sides generally seek to guard themselves against its effects; and cases in which this is impossible are rare. Now in these uncommon cases this means has often also proved highly efficacious, and for this reason, as well as on account of the constant watching against it which is required in war, it is important that it should be clearly explained in theory. Although the strategic operation against a flank can naturally be imagined, not only on the part of the defensive, but also on that of the offensive, still it has much more affinity with the first, and therefore finds its place under the head of defensive means.

Before we enter into the subject, we must establish the simple principle, which must never be lost sight of afterwards in the consideration of the subject, that troops which are to act against the rear or flank of the enemy cannot be employed against his front, and that, therefore, whether it be in tactics or strategy, it is a completely false kind of notion to consider that coming on the rear of the enemy is at once an advantage in itself. In itself, it is as yet nothing; but it will become something in connection with other things, and something either advantageous or the reverse, according to the nature of these things, the examination of which now claims our attention.

First, in the action against the strategic flank, we must make a distinction between two objects of that measure—between the action merely against the communications, and that against the line of retreat, with which, at the same time, an effect upon the communications may also be combined.

When Daun, in 1758, sent a detachment to seize the convoys on their way to the siege of Olmütz, he had plainly no intention of impeding the king’s retreat into Silesia; he rather wished to bring about that retreat, and would willingly have opened the line to him.

In the campaign of 1812, the object of all the expeditionary corps that were detached from the Russian army in the months of September and October, was only to intercept the communications, not to stop the retreat; but the latter was quite plainly the design of the Moldavian army which, under Tschitschagof, marched against the Beresina, as well as of the attack which General Wittgenstein was commissioned to make on the French corps stationed on the Dwina.

These examples are merely to make the exposition clearer.

The action against the lines of communication is directed against the enemy’s convoys, against small detachments following in rear of the army, against couriers and travellers, small depôts, etc.; in fact, against all the means which the enemy requires to keep his army in a vigorous and healthy condition; its object is, therefore, to weaken the condition of the enemy in this respect, and by this means to cause him to retreat.

The action against the enemy’s line of retreat is to cut his army off from that line. It cannot effect this object unless the enemy really determines to retreat; but it may certainly cause him to do so by threatening his line of retreat, and, therefore, it may have the same effect as the action against the line of communication, by working as a demonstration. But as already said, none of these effects are to be expected from the mere turning which has been effected, from the mere geometrical form given to the disposition of the troops, they only result from the conditions suitable to the same.

In order to learn more distinctly these conditions, we shall separate completely the two actions against the flank, and first consider that which is directed against the communications.

Here we must first establish two principal conditions, one or other of which must always be forthcoming.

The first is, that the forces used for this action against the flank of the enemy must be so insignificant in numbers that their absence is not observed in front.

The second, that the enemy’s army has run its career, and therefore can neither make use of a fresh victory over our army, nor can he pursue us if we evade a combat by moving out of the way.

This last case, which is by no means so uncommon as might be supposed, we shall lay aside for the moment, and occupy ourselves with the accessory conditions of the first.

The first of these is, that the communications have a certain length, and cannot be protected by a few good posts; the second point is, that the situation of the line is such as exposes it to our action.

This weakness of the line may arise in two ways—either by its direction, if it is not perpendicular to the strategic front of the enemy’s army, or because his lines of communication pass through our territory; if both these circumstances exist, the line is so much the more exposed. These two relations require a closer examination.

One would think that when it is a question of covering a line of communication forty or fifty miles long, it is of little consequence whether the position occupied by an army standing at one extremity of this line forms an oblique angle or a right angle in reference to it, as the breadth of the position is little more than a mere point in comparison to the line; and yet it is not so unimportant as it may seem. When an army is posted at a right angle with its communications, it is difficult, even with a considerable superiority, to interrupt the communications by any detachments or partisans sent out for the purpose. If we think only of the difficulty of covering absolutely a certain space, we should not believe this, but rather suppose, on the contrary, that it must be very difficult for an army to protect its rear (that is, the country behind it) against all expeditions which an enemy superior in numbers may undertake. Certainly, if we could look at everything in war as it is on a sheet of paper! Then the party covering the line, in his uncertainty as to the point where light troops or partisans may appear, would be in a certain measure blind, and only the partisans would see. But if we think of the uncertainty and insufficiency of intelligence gained in war, and know that both parties are incessantly groping in the dark, then we easily perceive that a detached corps sent round the enemy’s flank to gain his rear is in the position of a man engaged in a fray with numbers in a dark room. In the end he must fall; and so must it also be with bands who get round an army occupying a perpendicular position, and who therefore place themselves near to the enemy, but widely separated from their own people. Not only is there danger of losing numbers in this way; there is also a risk of the whole instrument itself being blunted immediately; for the very first misfortune which happens to one such party will make all the others timid, and instead of bold attacks and insolent dodging, the only play will be constant running away.

Through this difficulty, therefore, an army occupying a perpendicular position covers the nearest points on its line of communications for a distance of two or three marches, according to the strength of the army; but those nearest points are just those which are most in danger, as they are the nearest to the enemy.

On the other hand, in the case of a decidedly oblique position, no such part of the line of communication is covered; the smallest pressure, the most insignificant attempt on the part of the enemy, leads at once to a vulnerable point.

But now, what is it which determines the front of a position, if it is not just the direction perpendicular to the line of communication? The front of the enemy; but then, again, this may be equally as well supposed as dependent on our front. Here there is a reciprocal effect, for the origin of which we must search.

 

lines of communication

If we suppose the lines of communication of the assailant, a b, so situated with respect to those of the enemy, c d, that the two lines form a considerable angle with each other, it is evident that if the defensive wishes to take up a position at e, where the two lines intersect, the assailant from b, by the mere geometrical relation, could compel him to form front opposite to him, and thus to lay bare his communications. The case would be reversed if the defensive took up his position on this side of the point of junction, about d; then the assailant must make front towards him, if so be that his line of operations, which closely depends on geographical conditions, cannot be arbitrarily changed, and moved, for instance, to the direction a d. From this it would seem to follow that the defender has an advantage in this system of reciprocal action, because he only requires to take a position on this side of the intersection of the two lines. But very far from attaching any importance to this geometrical element, we only brought it into consideration to make ourselves the better understood; and we are rather of opinion that local and generally individual relations have much more to do with determining the position of the defender; that, therefore, it is quite impossible to lay down in general which of two belligerents will be obliged soonest to expose his communications.

If the lines of communication of both sides lie in one and the same direction, then whichever of the two parties takes up an oblique position will certainly compel his adversary to do the same. But then there is nothing gained geometrically by this, and both parties attain the same advantages and disadvantages.

In the continuation of our considerations we shall, therefore, confine ourselves to the case of the line of communication of one side only being exposed.

Now as regards the second disadvantageous relation of a line of communication, that is to say, when it runs through an enemy’s country, it is clear in itself how much the line is compromised by that circumstance, if the inhabitants of the country have taken up arms; and consequently the case must be looked at as if a body of the enemy was posted all along the line; this body, it is true, is in itself weak without solidity or intensive force; but we must also take into consideration what the close contact and influence of such a hostile force may nevertheless effect through the number of points which offer themselves one after another on long lines of communication. That requires no further explanation. But even if the enemy’s subjects have not taken up arms, and even if there is no militia in the country, or other military organisation, indeed if the people are even very unwarlike in spirit, still the mere relation of the people as subjects to a hostile government is a disadvantage for the lines of communication of the other side which is always felt. The assistance which expeditionary forces and partisans derive merely through a better understanding with the people, through a knowledge of the country and its inhabitants, through good information, through the support of official functionaries, is, for them, of decided value; and this support every such body will enjoy without any special effort on its own part. Added to this, within a certain distance there will not be wanting fortresses, rivers, mountains, or other places of refuge, which of ordinary right belong to the enemy, if they have not been formally taken possession of and occupied by our troops.

Now in such a case as is here supposed, especially if attended with other favourable circumstances, it is possible to act against the communications of an army, although their direction is perpendicular to the position of that army; for the detachments employed for the purpose do not then require to fall back always on their own army, because being in their own country they are safe enough if they only make their escape.

We have, therefore, now ascertained that—

 

1. A considerable length,

2. An oblique direction,

3. An enemy’s province,

 

are the principal circumstances under which the lines of communication of an army may be interrupted by a relatively small proportion of armed forces on the side of the enemy; in order to make this interruption effectual, a fourth condition is still requisite, which is a certain duration of time. Respecting this point, we beg attention to what has been said in the fifteenth chapter of the fifth book.

But these four conditions are only the chief points which relate to the subject; a number of local and special circumstances attach themselves to these, and often attain to an influence more decisive and important than that of the principal ones themselves. Selecting only the most essential, we mention the state of the roads, the nature of the country through which they pass, the means of cover which are afforded by rivers, mountains, and morasses, the seasons and weather, the importance of particular convoys, such as siege trains, the number of light troops, etc., etc.

On all these circumstances, therefore, will depend the effect with which a general can act on his opponent’s communications; and by comparing the result of the whole of these circumstances on the one side with the result of the whole on the other, we obtain a just estimate of the relative advantages of both systems of communication, on which will depend which of the two generals can play the highest game.

What here seems so prolix in the explanation is often decided in the concrete case at first sight; but still, the tact of a practised judgment is required for that, and person must have thought over every one of the cases now developed in order to see in its true light the absurdity of those critical writers who think they have settled something by the mere words “turning” and “acting on a flank,” without giving their reasons.

We now come to the second chief condition, under which the strategic action against the enemy’s flank may take place.

If the enemy is hindered from advancing by any other cause but the resistance which our army opposes, let that cause be what it may, then our army has no reason to be apprehensive about weakening itself by sending out detachments to harass the enemy; for if the enemy should attempt to chastise us by an attack, we have only to yield some ground and decline the combat. This is what was done by the chief Russian army at Moscow in 1812. But it is not at all necessary that everything should be again on the same great scale as in that campaign for such a case to happen again. In the first Silesian war, Frederick the Great was each time in this situation, on the frontiers of Bohemia and Moravia, and in the complex affairs relating to generals and their armies, many causes of different kinds, particularly political ones, may be imagined, which make further advance an impossibility.

As in the case now supposed more forces may be spared to act against the enemy’s flank, the other conditions need not be quite so favourable: even the nature of our communications in relation to those of the enemy need not give us the advantage in that respect, as an enemy who is not in a condition to make any particular use of our further retreat is not likely to use his right to retaliate, but will rather be anxious about the direct covering of his own line of retreat.

Such a situation is therefore very well suited to obtain for us, by means less brilliant and complete but less dangerous than a victory, those results which it would be too great a risk to seek to obtain by a battle.

As in such a case we feel little anxiety about exposing our own line of communications, by taking up a position on one or other flank, and as the enemy by that means may always be comspelled to form front obliquely to his line of communications, therefore this one of the conditions above named will seldom fail to occur. The more the rest of the conditions, as well as other circumstances, co-operate, so much the more certain are we of success from the means now in question; but the fewer favourable circumstances exist, the more will all depend on superior skill in combination, and promptitude and precision in the execution.

Here is the proper field for strategic manœuvres, such as are to be found so frequently in the Seven Years’ War, in Silesia and Saxony, and in the campaigns of 1760 and 1762. If, in many wars in which only a moderate amount of elementary force is displayed, such strategic manœuvring very often appears, this is not because the commander on each occasion found himself at the end of his career, but because want of resolution and courage, and of an enterprising spirit, and dread of responsibility, have often supplied the place of real impediments; for a case in point, we have only to call to mind Field Marshal Daun.

As a summary of the results of our considerations, we may say, that the action against a flank is most effectual—

 

1. In the defensive;

2. Towards the end of a campaign;

3. Above all, in a retreat into the heart of the country; and

4. In connection with a general arming of the people.

 

On the mode of executing this action against the communications, we have only a few words to say.

The enterprises must be conducted by skilful detachment leaders, who, at the head of small bodies, by bold marches and attacks, fall upon the enemy’s weak garrisons, convoys, and small detachments on the march here and there, encourage the national levies (landsturm), and sometimes join with them in particular undertakings. These parties must be more numerous than strong individually, and so organised that it may be possible to unite several of them for any greater undertaking without any obstacle from the vanity or caprice of any of the single leaders.

We have now to speak of the action against the enemy’s line of retreat.

Here we must keep in view, above all things, the principle with which we commenced, that forces destined to operate in rear cannot be used in front; that, therefore, the action against the rear or flanks is not an increase of force in itself; it is only to be regarded as a more powerful application (or employment) of the same; increasing the degree of success in prospect, but also increasing the degree of risk.

Every opposition offered with the sword which is not of a direct and simple nature, has a tendency to raise the result at the cost of its certainty. An operation against the enemy’s flank, whether with one compact force, or with separate bodies converging from several quarters, belongs to this category.

But now, if cutting off the enemy’s retreat is not to be a mere demonstration, but is seriously intended, the real solution is a decisive battle, or, at least, the conjunction of all the conditions for the same; and just in this solution we find again the two elements above-mentioned—the greater result and the greater danger. Therefore, if a general is to stand justified in adopting this method of action, his reasons must be favourable conditions.

In this method of resistance we must distinguish the two forms already mentioned. The first is, if a general with his whole force intends to attack the enemy in rear, either from a position taken up on the flank for that purpose, or by a formal turning movement; the second is, if he divides his forces, and, by an enveloping position with one part, threatens the enemy’s rear, with the other part his front.

The result is intensified in both cases alike, that is—either there is a real interception of the retreat, and consequently the enemy’s army taken prisoners, or the greater part scattered, or there may be a long and hasty retreat of the enemy’s force to escape the danger.

But the intensified risk is different in the two cases.

If we turn the enemy with our whole force, the danger lies in the laying open our own rear; and hence the question again depends on the relation of the mutual lines of retreat, just as in the action against the lines of communication, it depended on the relation of those lines.

Now certainly the defender, if he is in his own country, is less restricted than the assailant, both as to his lines of retreat and communication, and in so far is therefore in a better position to turn his adversary strategically; but this general relation is not of a sufficiently decisive character to be used as the foundation of a practical method; therefore, nothing but the whole of the relations in each individual case can decide.

Only so much we may add, that favourable conditions are naturally more common in wide spheres of action than in small; more common, also, on the side of independent states than on that of weak ones, dependent on foreign aid, and whose armies must, therefore, constantly have their attention bent on the point of junction with the auxiliary army; lastly, they become most favorable for the defender towards the close of the campaign, when the impulsive force of the assailant is somewhat spent; very much, again, in the same manner as in the case of the lines of communication.

Such a flank position as the Russians took up with such advantage on the road from Moscow to Kaluga, when Buonaparte’s aggressive force was spent, would have brought them into a scrape at the commencement of the campaign at the camp of Drissa, if they had not been wise enough to change their plan in good time.

The other method of turning the enemy, and cutting off his retreat by dividing our force, entails the risk attending a division of our own force, whilst the enemy, having the advantage of interior lines, retains his forces united, and therefore has the power of acting with superior numbers against one of our divisions. This is a disadvantage which nothing can remove, and in exposing ourselves to it, we can only be justified by one of three principal reasons:—

 

1. The original division of the force which makes such a method of action necessary, unless we incur a great loss of time.

2. A great moral and physical superiority, which justifies the adoption of a decisive method.

3. The want of impulsive force in the enemy as soon as he has arrived at the culminating point of his career.

 

When Frederick the Great invaded Bohemia, 1757, on converging lines, he had not in view to combine an attack in front with one on the strategic rear, at all events, this was by no means his principal object, as we shall more fully explain elsewhere, but in any case it is evident that there never could have been any question of a concentration of forces in Silesia or Saxony before the invasion, as he would thereby have sacrificed all the advantages of a surprise.

When the allies formed their plan for the second part of the campaign of 1813, looking to their great superiority in numbers, they might very well at that time entertain the idea of attacking Buonaparte’s right on the Elbe with their main force, and of thus shifting the theatre of war from the Oder to the Elbe. Their ill-success at Dresden is to be ascribed not to this general plan but to their faulty dispositions both strategic and tactical. They could have concentrated 220,000 men at Dresden against Buonaparte’s 130,000, a proportion of numbers eminently favourable (at Leipsic, at least, the proportion was as 285 : 157). It is true that Buonaparte had distributed his forces too evenly for the particular system of a defence upon one line (in Silesia 70,000 against 90,000, in the Mark—Brandenburg—70,000 against 110,000), but at all events it would have been difficult for him, without completely abandoning Silesia, to assemble on the Elbe a force which could have contended with the principal army of the allies in a decisive battle. The allies could also have easily called up the army of Wrede to the Maine, and employed it to try to cut Buonaparte off from the road to Mayence.

Lastly, in 1812, the Russians might have directed their army of Moldavia upon Volhynia and Lithuania in order to move it forward afterwards against the rear of the principal French army, because it was quite certain that Moscow must be the extreme point of the French line of operations. For any part of Russia beyond Moscow there was nothing to fear in that campaign, therefore the Russian main army had no cause to consider itself too weak.

This same scheme formed part of the disposition of the forces laid down in the first defensive plan proposed by General Phul, according to which the army of Barclay was to occupy the camp at Drissa, whilst that under Bragathion was to press forward against the rear of the main French army. But what a difference of circumstances in the two cases! In the first of them the French were three times as strong as the Russians; in the second, the Russians were decidedly superior. In the first, Buonaparte’s great army had in it an impulsive force which carried it to Moscow 80 miles beyond Drissa: in the second, it is unfit to make a day’s march beyond Moscow; in the first, the line of retreat on the Niemen did not exceed 30 miles: in the second it was 112. The same action against the enemy’s retreat therefore, which was so successful in the second case, would, in the first, have been the wildest folly.

As the action against the enemy’s line of retreat, if it is more than a demonstration, becomes a formal attack from the rear, there remains therefore still a good deal to be said on the subject, but it will come in more appropriately in the book upon the attack; we shall therefore break off here and content ourselves with having given the conditions under which this kind of reaction may take place.

Very commonly the design of causing the enemy to retreat by menacing his line of retreat, is understood to imply rather a mere demonstration than the actual execution of the threat. If it was necessary that every efficacious demonstration should be founded on the actual practicability of real action, which seems a matter of course at first sight, then it would accord with the same in all respects. But this is not the case: on the contrary, in the chapter on demonstrations we shall see that they are connected with conditions somewhat different, at all events in some respects, we therefore refer our readers to that chapter.

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