Moral vs. Physical Force

One of Clausewitz's innovations in On War is to distinguish sharply between moral and physical forces and emphasize the importance of the moral over the physical. Physical forces include all the standard elements in a theory of war, including strength of numbers, position, type and number of arms, territory and timing. But moral forces include factors like moral, military virtue, military genius and so on. While troops certainly need physical nourishment they also need, for instance, a stable balance between tension and rest. Tension and rest illustrates a particularly important feature of the moral force, as it explains how soldiers often can have their spirits broken through excessive stress through constant fighting. On the other hand, too much rest produces its own sort of fatigue through boredom and loss of focus.

Moral forces are much harder to theorize about, in Clausewitz's opinion, as they are...