[William Cloud Hicklin]

All of warfare is ultimately about morale. The natural human instinct for self-preservation is only held at bay by a complex (and artificial) structure of training, discipline, esprit de corps, confidence, patriotism and so on, collectively termed morale: but there can come a point for any soldier where it all collapses in the face of the biological desire to be somewhere else, as fast as possible. Napoleon understood this instinctively: he spoke of a battle as "two large groups of men trying to frighten each other," and of the "crucial moment" in a battle which, when seized properly, will cause the enemy to "break." Battles aren't decided by killing every last one of them, but by inflicting sufficient casualties and creating the prospect of inflicting a lot more, such that the rest run away or surrender.