Concentration
"It is impossible to be too strong at the decisive point," said Napoleon. To concentrate every available man and gun at the decisive point so as to attain superiority there, is not an easy thing, for the enemy will be making a similar attempt. "The calculation of time and space appears the most essential thing to this end. But the calculation of time and space, though 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." "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 distribution which by that means has been given to the forces from the very first, and in the resolution to sacrifice the unimportant to the advantage of the important. In this respect Frederick the Great and Bonaparte are especially characteristic."[50]
"There is no simpler and more imperative rule for strategy than to keep all the forces concentrated. No portion to be separated from the main body unless called away by some urgent necessity. On this maxim we stand firm, and look upon it as a fact to be depended upon."[51]
"The concentration of the whole force (i.e. within supporting distance) should be the rule, and every separation or division is an exception which must be justified."[52] Of course, this does not mean that all the troops are to be kept concentrated in one mass upon one road, but within supporting distance, for he expressly states, "It is sufficient now if the concentration takes place during the course of the action."[53] This doctrine, qualified by the last sentence, makes Clausewitz the germ of modern military thought, for the last sentence leaves room for all the modern developments of new roads, railways, telegraphs, wire and wireless, and so forth.
Therefore in war, according to Clausewitz, concentration, concentration, concentration, and every division or detachment is an evil which can only be justified by urgent necessity. Here again we find a simple truth, which, however, the history of all wars shows us to be very difficult to carry out. Hence the value of keeping such an imperative maxim always in our minds.