The Red Badge of Courage was Stephen Crane's best known novel. It was one of his two great ones, the other being the underrated Maggie: A Girl of the Streets, which was also a ground-breaking work, taking up the subject of women's plights in industrial society as Red Badge takes up men's plight in wartime.
The story is a cerebral one, about what the protagonist, new recruit Henry Fleming, an 18-year-old Yankee, thinks. As in most Crane writing, most characters remain nameless, such as the Tall Soldier. The story starts with all the enthusiasm of newbies going to war. Then Fleming faces the boredom of military camp. As a writer famously said, 99% of the time is boredom, 1% terror. Crane introduces us to that subject through this novel.
In the first battle, Henry runs, but he is covered by the confusion and gets to return and reunite with his fellows. He picks up a fake injury to justify this by being bonked on the head by another retreating soldier.
In the last section, Fleming steps up as the flag carrier, fights well, and survives for another day. A later Crane short story, "The Veteran", features Fleming as an older man, so presumably he survived the Civil War. But this is all left open ended in the novel, which only covers a few weeks time in the four-year war. Listen to "The Veteran" to see how it all turned out and was remembered.