The question of what it means to be an enemy, so apparently simple, particularly in wartime, is explored in practically all literature that deals with war at all. One of the points most frequently made is that the animosity one might experience on a personal level toward an antagonist in everyday life is entirely absent when considering the collective enemy in wartime. The soldier is more likely to hate his own officers than the men on the other side of the battle-lines, who are only “enemies” for the arbitrary reason that they happen to be citizens of another country. This idea is expressed in a single line by G.K. Chesterton when he puts into the mouth of a man who fought in the Napoleonic Wars the understandable sentiment, “I knew no harm of Bonaparte, and plenty of the Squire.” It is also explored in Thomas Hardy’s poem “The Man He Killed,” which points out that the soldier who shot a man on the other side would probably have bought him a drink if they had met socially at an inn.

In All Quiet on the Western Front, Remarque discusses the idea of what constitutes an enemy when he says,

A word of command has made these silent figures our enemies; a word of command might transform them into our friends … Any non-commissioned officer is more of an enemy to a recruit, any schoolmaster to a pupil, than they are to us.

The notion that a single military command immediately transforms an enemy into an ally emphasizes how arbitrary and contingent the concept really is.