In his experimenting with psychological realism in The Red Badge of Courage, Stephen Crane has his character Henry face an array of feelings about war.  As he faces combat for the first time, Henry feels anxiety, self-confidence, courage, and zeal.

Before entering battle Henry has mixed emotions, critically judging the men who speak of their fears and observations about the forthcoming battle. But, as he sees the "stampede" of men coming from a squirmish, Henry

...resolved to get a view of it, and, then, he might very likely run better than the best of them.

However, many of Henry's fantasies dissolve as the men grow closer to engaging in battle.  He feels isolated and anxious.  But when he perceives that the enemy is upon them, Henry fires his rifle with "a red rage," that of "a driven beast" as he fights until the enemy is repelled. He feels himself a part, a "member," of the regiment, rather than a whole man:

He was wielded into a common personality....It was a mysterious fraternity born of the smoke and danger of death.

With animalistic emotion, Henry loses himself in the battle.  But, contrary to his imaginings, there "was a singular absence of heroic phrases" after the battle and the officers "neglected to stand in picturesque attitudes."  As he does feel a thrill when he sees the flags, like beautiful birds strangely undaunted in a storm," Henry remarks with astonishment that "Nature had gone on tranquilly with her golden process in the midst of so much devilment."

Along with the realization that it is an indifferent universe in which man engages in all his joys and conflicts, Henry begins to see the real horror of war.  He feels "like the proverbial chicken" as he runs from death:  "Destruction threatened him from all points."  Henry looks in amazement at the battery who seem "unaware of the impending annihilation."  He becomes bitter at their blind ignorance, and feels himself enlightened in comparison.  But he dreads returning to camp where the "density" of the others that would prevent their understanding of his "sharper point of view":

A dull animal-like rebellion against his fellows, war in the abstract, and fate grew within him.

In short, whereas the idealistic Henry has been swept into a "red rage" in the first squirmish, he later realizes the waste and futility of war in an indifferent universe.