On War

by Carl von Clausewitz

(*) The Prussians at Jena, 1806. Wellington at Waterloo.

If we are thoroughly penetrated with the conviction that with a considerable superiority of numbers everything possible is to be effected, then it cannot fail that this clear conviction reacts on the preparations for the War, so as to make us appear in the field with as many troops as possible, and either to give us ourselves the superiority, or at least to guard against the enemy obtaining it. So much for what concerns the absolute force with which the War is to be conducted.

The measure of this absolute force is determined by the Government; and although with this determination the real action of War commences, and it forms an essential part of the Strategy of the War, still in most cases the General who is to command these forces in the War must regard their absolute strength as a given quantity, whether it be that he has had no voice in fixing it, or that circumstances prevented a sufficient expansion being given to it.

There remains nothing, therefore, where an absolute superiority is not attainable, but to produce a relative one at the decisive point, by making skilful use of what we have.

The calculation of space and time appears as the most essential thing to this end—and this has caused that subject to be regarded as one which embraces nearly the whole art of using military forces. Indeed, some have gone so far as to ascribe to great strategists and tacticians a mental organ peculiarly adapted to this point.

But the calculation of time and space, although it lies universally at the foundation of Strategy, and is to a certain extent its daily bread, is still neither the most difficult, nor the most decisive one.

If we take an unprejudiced glance at military history, we shall find that the instances in which mistakes in such a calculation have proved the cause of serious losses are very rare, at least in Strategy. But if the conception of a skilful combination of time and space is fully to account for every instance of a resolute and active Commander beating several separate opponents with one and the same army (Frederick the Great, Buonaparte), then we perplex ourselves unnecessarily with conventional language. For the sake of clearness and the profitable use of conceptions, it is necessary that things should always be called by their right names.

The right appreciation of their opponents (Daun, Schwartzenberg), the audacity to leave for a short space of time a small force only before them, energy in forced marches, boldness in sudden attacks, the intensified activity which great souls acquire in the moment of danger, these are the grounds of such victories; and what have these to do with the ability to make an exact calculation of two such simple things as time and space?

But even this ricochetting play of forces, “when the victories at Rosbach and Montmirail give the impulse to victories at Leuthen and Montereau,” to which great Generals on the defensive have often trusted, is still, if we would be clear and exact, only a rare occurrence in history.

Much more frequently the relative superiority—that is, the skilful assemblage of superior forces at the decisive point—has its foundation in the right appreciation of those points, in the judicious direction which by that means has been given to the forces from the very first, and in the resolution required to sacrifice the unimportant to the advantage of the important—that is, to keep the forces concentrated in an overpowering mass. In this, Frederick the Great and Buonaparte are particularly characteristic.