Crane suggests that there is a lunacy about battles and war. Reread the first few pages of Chapter 19 and note all of the allusions to madness and insanity.

His eyes were fixed in a lurid glare. And with his soiled and disordered dress, his red and inflamed features surmounted by the dingy rag with its spot of blood, his wildly swinging rifle, and banging accouterments, he looked to be an insane soldier.

It seemed to the youth that he saw everything. Each blade of the green grass was bold and clear. He thought that he was aware of every change in the thin, transparent vapor that floated idly in sheets. The brown or gray trunks of the trees showed each roughness of their surfaces. And the men of the regiment, with their starting eyes and sweating faces, running madly, or falling, as if thrown headlong, to queer, heaped-up corpses-- all were comprehended.