The Red Badge of Courage is the story of Henry Fleming, a teenager who enlists with the Union Army in the hopes of fulfilling his dreams of glory.
Shortly after enlisting, the reality of his decision sets in. He experiences tedious waiting, not immediate glory. The more he waits for battle, the more doubt and fear creep into his mind. When he finally engages in his first battle, he blindly fires into the battle haze, never seeing his enemy. As the next enemy assault approaches, Henry's fears of death overwhelm him, and he runs from the field.
Henry continues his retreat for some time, even after he overhears that his regiment repelled the enemy. When he finally slows and rests, he hears the sound of a renewed battle and, ironically, he returns to the battle from which he has fled. He comes upon many wounded men returning from the front to get medical assistance. One of these wounded soldiers, identified as "a tattered soldier," befriends Henry and begins a conversation with him; however, when the tattered soldier asks Henry where he is wounded, Henry evades the question by leaving him and drifting into the crowd of soldiers.
As Henry continues walking with the wounded, he sees a veteran soldier of his company, Jim Conklin, who is mortally wounded. Henry follows Jim, and, eventually, the tattered soldier joins them. When Jim suddenly collapses and dies, Henry is devastated. The tattered soldier again asks Henry about his wound. Again, Henry can't explain that he has no wound, so he leaves the disoriented, wounded, tattered soldier stumbling in the field.
Henry anguishes over his lack of courage, but he can't overcome the guilt and self-hatred that stop him from returning to his regiment. He hears the noise of a battle and sees reinforcement troops heading toward the front. As he watches, the battle turns against the Union forces, and many of the men begin to retreat. Henry gets caught up in their retreat. He tries to stop a retreating soldier to find out what is happening; however, the soldier only wants to get away, so he hits Henry over the head with his rifle, leaving Henry with a serious head wound. He is dazed by the blow and wanders back through the woods. Henry is then befriended by a cheery soldier who returns him to his regiment.
Henry fears being ridiculed by his comrades on his return, but when he enters his camp, two soldiers, Wilson and Simpson, see his injury and immediately begin ministering to him. They assume that Henry was hurt in battle; however, Simpson asks Henry about his whereabouts, and Henry can't answer.
As the regiment prepares to move out, Wilson asks Henry to return a packet of letters that he gave Henry before the first battle. (Wilson feared that he was going to die in battle, and he wanted Henry to give the letters to his family.) Henry realizes that Wilson was also afraid of battle, and Henry is overjoyed to think that he now has power, and a weapon, to use to hold over somebody else's head. This knowledge gives Henry courage and restores his confidence.
Henry converts his fear of the enemy into anger and becomes a leader, fighting boldly at the side of his lieutenant. Henry becomes such a confident, assertive, aggressive soldier that, ironically, he becomes a fighting machine himself. Henry resolves his guilt over abandoning the tattered soldier by deciding to use the memory of this selfish, uncaring act to keep himself humble — to control any egotism he feels because of his now strong fighting ability.
When Henry's regiment is chosen to charge the enemy, Henry leads the charge with the lieutenant, and, eventually, he even assumes the role of color bearer for the regiment after the color sergeant is killed.
Henry's transformation from a fearful, lost, doubting youth, to a courageous, confident, duty-bound soldier is the essence of the novel. It is the story of the growth of a young man from innocence to maturity.