The only way you can understand the truth about killing an enemy in combat is by killing an enemy in combat.

—Miyamoto Musashi, the Book of Five Rings, 1643

I’ll tell you in two words what the battle was: Murder and fear, murder and fear. I know I’ll never be the same person again. All the things that used to bother me are so small and silly. I know what life is worth, now that I’ve seen so much death

—Israeli paratrooper, 1967

How men react to the experience of battle is a product of their mental state and preparation. Repeated exposure to combat increases chances of survival due to a learning curve—studies of aerial combat done during Vietnam indicated that after 10 missions, the chances of living through a combat tour were greatly enhanced. But what about that first taste of battle? The mind of the neophyte warrior wrestles with the possibilities...what may happen? What will things look like, sound like? How will I perform? These questions are considered in the context of a man’s notions of battle: what the battlefield will be like, where enemy and friendly forces will be, and how they will look.

These pre-conceptions of battle are formed in training, in literature, in movies, in TV. The closer reality conforms to expectations the better, because the warrior may be better able to act and react more quickly and effectively than one who is surprised or shocked by a reality that is far removed from expectations.