NOTE: This version of Clausewitz's On War is the long-obsolete J.J. Graham translation published in London in 1873. The 1976/84 Howard/Paret version is the  standard translation today.


Chapter XI

Attack of a Mountain

FROM the fifth and following chapters of the sixth book, may be deduced sufficiently the strategic relations of a mountain generally, both as regards the defence and the attack. We have also there endeavoured to explain the part which a mountain plays as a line of defence, properly so called, and from that naturally follows how it is to be looked upon in this signification from the side of the assailant. There remains, therefore, little for us to say here on this important subject. Our chief result was there that the defence must choose as his point of view a secondary combat, or the entirely different one of a great general action; that in the first case the attack of a mountain can only be regarded as a necessary evil, because all the circumstances are unfavourable to it; but in the second case the advantages are on the side of the attack.

An attack, therefore, armed with the means and the resolution for a battle, will give the enemy a meeting in the mountains, and certainly find his account in so doing.

But we must here once more repeat that it will be difficult to obtain respect for this conclusion, because it runs counter to appearances, and is also, at first sight, contrary to the experience of war. It has been observed, in most cases hitherto, that an army pressing forward to the attack (whether seeking a great general action or not), has considered it an unusual piece of good fortune if the enemy has not occupied the intervening mountains, and has itself then hastened to be beforehand in the occupation of them. No one will find this forestalling of the enemy in any way inconsistent with the interests of the assailant; in our view this is also quite admissible, only we must point out clearly a fine distinction here between circumstances.

An army advancing against the enemy, with the design of bringing him to a general action, if it has to pass over an unoccupied range of mountain, has naturally to apprehend that the enemy may, at the last moment, block up those very passes which it proposes to use on its march: in such a case, the assailant will by no means have the same advantages as if the enemy occupied merely an ordinary mountain position. The latter is, for instance, not then in a position extended beyond measure, nor is he in uncertainty as to the road which the assailant will take; the assailant has not been able to choose his road with reference to the enemy's position, and therefore this battle in the mountains is not then united with all those advantages on his side of which we have spoken in the sixth book; under such circumstances, the defender might be found in an impregnable position—According to this, the defender might even have means at his command of making advantageous use of the mountains for a great battle.—This is, at any rate, possible; but if we reflect on the difficulties which the defender would have to encounter in establishing himself in a strong position in the mountains just at the last moment, particularly if he has left it entirely unoccupied before, we may put down this means of defence as one upon which no dependence can be placed, and therefore as one, the probability of which the assailant has little reason to dread. But even if it is a very improbable case, yet still it is natural to fear it; for in war, many a thing is very natural, and yet in a certain measure superfluous.

But another measure which the assailant has to apprehend here is, a preliminary defence of the mountains by an advanced guard or chain of outposts. This means, also, will seldom accord with the interests of the defender; but the assailant has not the means of discerning how far it may be beneficial to the defender or otherwise, and therefore he has only to provide against the worst.

Further, our view by no means excludes the possibility of a position being quite unassailable from the mountainous character of the ground: there are such positions which are not, on that account, in the mountains (Pirna, Schmotseifen, Meissen, Feldkirch), and it is just because they are not in the mountains, that they are so well suited for defence. We may also very well conceive that positions may be found in mountains themselves where the defender might avoid the ordinary disadvantages of mountain-positions, as, for instance, on lofty plateaux; but they are not common, and we can only take into our view the generality of cases.

It is just in military history that we see how little mountain-positions are suited to decisive defensive battles, for great generals have always preferred a position in the plains, when it was their object to fight a battle of the first order; and throughout the whole range of military history, there are no examples of decisive battles in the mountains, except in the Revolutionary Wars, and even there it was plainly a false application and analogy which led to the use of mountain-positions, where of necessity a decisive battle had to be fought (1793 and 1794 in the Vosges, and 1795, 1796, and 1797 in Italy). Melas has been generally blamed for not having occupied the Alpine passes in 1800; but such criticisms are nothing more than "early notions"—we might say—childlike judgments founded on appearances. Buonaparte, in Mela's place, would just as little have thought of occupying the passes.

The dispositions for the attack of mountain-positions are mostly of a tactical nature; but we think it necessary to insert here the following remarks as to the general outline, consequently as to those parts which come into immediate contact with, and are coincident with, strategy.

1. As we cannot move wide of the roads in mountains as we can in other districts, and form two or three columns out of one, when the exigency of the moment requires that the mass of the troops should be divided; but, on the contrary, we are generally confined to long defiles; the advance in mountains must generally be made on several roads, or rather upon a somewhat broader front.

2. Against a mountain line of defence of wide extent, the attack must naturally be made with concentrated forces; to surround the whole cannot be thought of there, and if an important result is to be gained from victory, it must be obtained rather by bursting through the enemy's line, and separating the wings, than by surrounding the force, and so cutting it off. A rapid, continuous advance upon the enemy's principal line of retreat is there the natural endeavour of the assailant.

3. But if the enemy to be attacked occupies a position somewhat concentrated, turning movements are an essential part of the scheme of attack, as the front attacks fall upon the mass of the defender's forces; but the turning movements again must be made more with a view to cutting off the enemy's retreat, than as a tactical rolling up of the flank or attack on the rear; for mountain positions are capable of a prolonged resistance even in rear if forces are not wanting, and the quickest result is invariably to be expected only from the enemy's apprehension of losing his line of retreat; this sort of uneasiness arises sooner, and acts more powerfully in mountains, because, when it comes to the worst, it is not so easy to make room sword in hand. A mere demonstration is no sufficient means here; it might certainly manœuvre the enemy out of his position, but would not ensure any special result; the aim must therefore be to cut him off, in reality, from his line of retreat.