The Red Badge of Courage is not a war novel. It is a novel about life. This novel illustrates the trials and tribulations of everyday life. Stephen Crane uses the war as a comparison to everyday life. He is semi-saying that life is like a war. It is a struggle of warriors - the every day people - against the odds.
In these battles of everyday life, people can change. In The Red Badge of Courage, the main character, Henry Fleming, undergoes a character change that shows how people must overcome their fears and the invisible barriers that hold them back from being the best people - warriors, in the sense that life is war - they can be. Henry has a character change that represents how all humans have general sense of fear of the unknown that must be overcome. In the first part of the novel, Henry is a youth that is very inexperienced. His motives were impure. He was a very selfish and self-serving character.
He enters the war not for the basis of serving his country, but for the attainment of glory and prestige. Henry wants to be a hero. This represents the natural human characteristic of selfishness. Humans have a want and a need to satisfy themselves. This was Henry's main motive throughout the first part of the novel. On more than one occasion Henry is resolved to that natural selfishness of human beings.
After Henry realizes that the attainment of glory and heroism has a price on it. That price is by wounds or worse yet, death. Henry then becomes self-serving in the fact that he wants to survive for himself, not the Union army. There is many a time when Henry wants to justify his natural fear of death.
He is at a point where he is questioning deserting the battle; in order to justify this, he asks Jim, the tall soldier, if he would run. Jim declared that he'd thought about it. Surely, thought Henry, if his companion ran, it would be alright if he himself ran. During the battle, when Henry actually did take flight, he justified this selfish deed - selfish in the fact that it did not help his regiment hold the Rebs - by natural instinct. He proclaimed to himself that if a squirrel took flight when a rock was thrown at it, it was alright that he ran when his life was on the line. This was a selfish reason for fleeing, in the broad sense.
Henry's fear of death was a natural human fear that would not work in a war. This is where Henry's character change took place. In everyday life, humans often go about their natural business not thinking at about what they are doing. Henry, in a sense, represented this in his war efforts. Henry was so busy thinking about death and running and all these selfish ideas about the war that he could not operate as a good soldier. A good soldier is one that goes about fighting, killing, defending and even dying for the cause.
These may not be great things, but they are what soldiers do. Henry was the epitome of not doing these soldier's tasks. In order for Henry to do his job the best, he had to become unthinking. This was a selfless act rather than a selfish act that would benefit the army, rather than hinder it. Once Henry got past his invisible barrier, his fear, he was able to become an unthinking war machine. This is similar to everyday life.
For humans to do the best job possible, whatever it may be, they must not think. If they think too much about the task at hand, they will become preoccupied with it and fail. This was Henry's problem; he overcame his fear of death and became the war machine. As an unthinking machine, Henry selflessly sacrificed his consciousness and became an outstanding soldier. In turn, his instinct kicked in, and he was able to survive the predicament he was in. The character change in The Red Badge of Courage illustrates the conflicting nature of human instinct.
The instinct wishes to serve itself, but it cannot serve itself if it is preoccupied with itself, such as in Henry's case. Henry's predicament in The Red Badge of Courage shows how he had to overcome his self-serving fear of death in order to accomplish the very same thing, surviving death. This is basic human nature. Henry's ordeal is a small look at how humans need to overcome the fear of what they are doing in order to function at maximum capacity at what they are doing.
The battle of life is won by compensating for one's weakness by challenging and defeating that weakness, as Henry Fleming did in The Red Badge of Courage.