Clausewitz says that bodily exertion and fatigue in war "put fetters on the action of the mind, and wear out in secret the powers of the soul." "Like danger, they belong to the fundamental causes of friction."[36]
To one who, like Clausewitz, had seen the retreat from Moscow, the awful passage of the Beresina, and the battle of the nations round Leipzig, bodily exertion could not be overlooked. Had he not seen bodily exertion and hardship break up the Grand Army into a small horde of stragglers, and destroy the army of Kutusoff in almost an equal measure, in 1812, as well as practically ruin the spirit, and largely break up the great army of Napoleon in 1813?
As for the effects of bodily exertion on the mind, purpose, and resolution of the general, compare Benningsen at Eylau after thirty-six hours in the saddle, or Napoleon at Dresden, by which he lost all the results of his victory.
Information in War
"The foundation of all our ideas and actions," but "in a few words, most reports are false." "When in the thick of war itself one report follows hard upon the heels of another, it is fortunate if these reports in contradicting each other show a certain balance of probability." In another passage, in order to illustrate this perpetual uncertainty under which all decisions in war have to be made, he compares two opposing commanders to two men fighting in a dark room and groping uncertainly for one another.
"These things which as elements meet together in the atmosphere of war and make it a resistant medium for every activity, we have designated danger, bodily exertion, information, and friction."[37] He never loses sight of this; it pervades everything he writes.
The Moral and Physical
"And therefore the most of the subjects which we shall go through in this book are composed half of physical, half of moral causes and effects, and we might say that the physical are almost no more than the wooden handle, whilst the moral are the noble metal, the real bright polished weapon."[38] Pages might be filled with extracts showing his opinion that the moral is everything in war, but the reader is already convinced of that. Compare Napoleon's in war, "The moral is to the physical as three to one." Clausewitz regards all military questions from this point. His psychological attitude is what chiefly characterizes Clausewitz from all writers who came before him, and which makes his deductions so realistic, so interesting and so valuable for all who come after him.
Tension and Rest in War
In order not to weary the reader I will bring this chapter to a conclusion with one or two extracts relating to "tension and rest; the suspension of the act in warfare." This is explanatory of those frequent halts which take place in a campaign, which appear at first sight contradictory to the absolute theory of war. These halts are due to many causes, such as preparations, exhaustion, uncertainty, irresolution, friction, waiting for reinforcements, etc.