In Stephen Crane's The Red Badge of Courage, protagonist Henry Fleming decided to enlist in the Civil War (in the Union Army) because he had a romantic view of warfare and desired to earn the glory reserved for great warriors. Having heard countless tales of the "Homeric" glory associated with warfare, Henry desired to prove himself a hero (like Odysseus, Achilles, Hector, and the many other heroes whom Homer wrote about).
Despite this, Henry feared he would not have the courage to face the battle. As the narrator says:
Whatever he had learned of himself was here of no avail. He was an unknown quantity.
Having never experienced anything quite like combat, Henry did not know whether he had the courage necessary to attain the glory he so desired. These fears caused Henry (and cause the reader) to reconsider his presuppositions about the relationship between glory and courage--and whether or not cowards could earn glory.