Morning dawns on a riverside encampment of soldiers: Union army volunteers from the 304th regiment of New York. As the camp stirs, a tall soldier named Jim Conklin tells the others he's heard a rumor that the generals plan to march their regiment into battle soon. The regiment has yet to see battle, and the soldiers debate Jim's news: some believe it, but some don't. One private, angry that the regiment hasn't marched for weeks, calls Jim a liar.
The novel shows the war from the perspective of soldiers who are always uninformed. Their arguments are never about the political issues of war. By leaving out the politics, Crane separates the war from the grand ideas that motivate the armies, and focuses on the soldiers' direct experience of battle.
A young private, Henry Fleming, listens to Jim and returns to his bunk to think. As a youth, he had always dreamed of glorious battles, his imagination inflamed by newspaper reports of great victories. He remembers enlisting against his mother's wishes. She warned him not to disgrace himself or do anything that he would be ashamed to tell her. This irritated Henry. He wasn't enlisting to avoid shame. He was out for glory.
Henry's dreams of battles and heated newspaper reports all greatly differ from the gritty reality of war. His mother's advice is Henry's first taste of the difference between the ideal and the real. Her view of war is bureaucratic rather than heroic—she tells him to do his duty and not mess up.
Henry suspects that education, religion, and daily concerns have sapped the greatness from men that was described in Greek classics, such as the Iliad. He had thought that enlisting and fighting was the only way he could gain the glory he craved. And as the crowds cheered his regiment just after it formed in Washington, he had felt like a hero. But since then, military life has been nothing but monotonous drills, reviews, and waiting.
Henry's idealized vision of war is shared by the non-soldiers who cheer on the army. But as for reality, Henry's mother is right. Modern warfare is bureaucratic, with its waiting and drills, compared to the high drama of battles like those in the Iliad.
Now faced with the possibility of battle, Henry realizes he doesn't really know how he'll act: will he fight courageously, or will he run away? Henry asks Jim if he's ever considered running. Jim replies that he'd run if everyone else did, but if they stood firm and fought, so would he. Henry feels reassured.
Just before battle, Henry realizes his own inexperience. Jim's response to Henry outlines a pragmatic idea of courage—he's uninterested in being a hero, and knows he couldn't be blamed for doing what everyone else does.