The protagonist of The Red Badge of Courage by Stephen Crane is Henry Fleming, a young man who joins the Union army to fight in the Civil War. His mother disapproves and worries about him going. Henry himself often worries about his performance, especially when he initially arrives. He fears when things get bad, he will run. In the beginning the men are most bothered by a lack of food and sleep. One soldier, named Wilson, gives Henry a yellow envelope with his personal belongings to give to his family in case he dies.

The first battle leads to some injuries and death. Henry is surprised when he hears that their side has won. He decides to leave. In the woods he finds a dead man propped up against a tree. A tattered man comes across Henry and asks where he has been hit. Henry feels guilty that he has not been given his own "red badge of courage," or wound from the war. Henry then ran into Jim Conklin, a man from his regiment. Henry tried to assist him, but Jim took off running before he fell down dead. Henry found a large wound in Jim's side. The tattered man encourages Henry to have someone check on his injuries as they might be worse than Henry realizes, just as Jim's were. This conversation and this man represented all the guilt that Henry felt about fleeing.

Some men coming running in Henry's direction, and one hits Henry on the head with his gun. A cheerful man then helps return Henry to his regiment. Simpson decides that Henry must have been grazed by a bullet, and his friend Wilson takes care of him. The next morning as the men talk around the fire, Henry tells them that Jim Conklin died. He returns the yellow envelope to Wilson.

The men are then marched to a trench to relieve another regiment. At one point Henry finds himself firing into a deserted field. The men worry about his health. Later Wilson offers to get the men water, so Henry assists. They overhear some officers calling their regiment "mule drivers" and predicting that many of them would not make it home.

During the next battle, Henry has the opportunity to capture the opponent's flag, which with the help of his friend Wilson, they do. Henry offers to carry it. They find out that the colonel said they deserved to be promoted, and they felt proud of themselves. When the fighting resumes, Wilson is able to capture another flag, and their side is declared victorious. The men begin the walk home with Henry making peace with his experience in the war.