I place friction here before the more detailed consideration of actual war, of war in itself, because it is that which distinguishes war on paper from real war, the statesman's and soldier's part from the part of the soldier only, and is therefore to be fitly treated midway between the two.

Friction in war is one of Clausewitz's most characteristic ideas. He always looks at everything from that point of view, and as friction and the fog of war, and their influence on human nature will always be the chief characteristic of real war as distinguished from theoretical war or war on paper, it is chiefly this habit or mode of thought which makes his writings of such great and permanent value. It is also a habit which we ought sedulously to cultivate in ourselves.

"In war everything is very simple, but the simplest thing is difficult,"[26] runs his famous saying. Why is the simplest thing difficult? Because of the friction of war. And how can that friction be minimized? Only by force of character, and the military virtues of discipline, perseverance, resolution, energy, and boldness. Hence the great emphasis which he always and everywhere lays upon character and these military virtues as the deciding factors in war.

"Friction is the only conception which in a general way corresponds to that which distinguishes real war from war on paper," he says. Each individual of the army "keeps up his own friction in all directions." "The danger which war brings with it, the bodily exertions which it requires, augment this evil so much that they may be regarded as the greatest causes of it."[27] "This enormous friction is everywhere brought into contact with chance, and thus facts take place upon which it was impossible to calculate, their chief origin being chance. As an instance of one such chance take the weather. Here the fog prevents the enemy from being discovered in time,​—​a battery from firing, or a report from reaching the general. The rain (mud) prevents a battalion from arriving,​—​or the cavalry from charging effectively, because it had stuck fast in the heavy ground." And so on. Consider for examples the foggy mornings of Jena or Austerlitz, of Eylau, the Katzbach, Grosbeeren, Dennewitz, Pultusk, Dresden, Sadowa; or the mud of Poland, the snow of Russia, or, latest, the mud of Manchuria.

"Activity in war is movement in a resistant medium." "The knowledge of friction is a chief part of that so often talked of experience in war, which is required in a good general." "It is therefore this friction which makes that which appears easy in war so difficult in reality."[28] In considering any situation in war we must therefore always add to the known circumstances​—​friction.

War Itself

In Clausewitz's way of looking at war itself I assign at once the first place to his doctrine, "The destruction of the enemy's military force is the leading principle of war, and for the whole chapter of positive action the direct way to the aim."[29] This dictum, repeated in many different forms, underlies his whole conception of war. All the old theoretical ideas about threatening by manœuvring, conquering by manœuvring, forcing the enemy to retreat by manœuvring, and so forth, in which his predecessors entangled strategy, and from which even the Archduke Charles and Jomini had not completely freed themselves, he brushes aside by "our assertion is that ONLY great tactical results can lead to great strategical results."[30] Thus he leads and concentrates our thoughts in strategy on the central idea of victory in battle, and frees us once for all from the obscuring veil of lines and angles and geometrical forms by which other writers have hidden that truth. "Philanthropists may easily imagine that there is a skilful method of overcoming and disarming an adversary without causing great bloodshed, and that this is the proper tendency of the art of war. However plausible this may appear, it is an error which must be extirpated, for, in such dangerous things as war, the errors which spring from a spirit of benevolence are just the worst."[31] For "he who uses force unsparingly without reference to the quantity of bloodshed, must obtain the superiority if his adversary does not act likewise." And the "worst of all errors in wars" is still the idea of war too commonly held by civilians in this country, as witness the outcries which greeted every loss during the South African war, which shows how much Clausewitz is needed as a tonic to brace their minds to the reality.

"War is an act of violence which in its application knows NO bounds." "Let us not hear of generals who conquer without bloodshed; if a bloody slaughter be a horrible sight, then that is a ground for paying more respect to war (for avoiding unnecessary war), but not for making the sword we wear blunt and blunter by degrees from feelings of humanity, till some one steps in with a sword that is sharp, and lops off the arm from our body."

Simple Plans

The second place I assign to his doctrine of the simplest plans, because time is required for the completion of complicated evolutions, but "a bold, courageous, resolute enemy will not let us have time for wide-reaching skilful combination."[32] "By this it appears to us that the advantage of simple and direct results over those that are complicated is conclusively shown."