The word imprecate is defined as wishing misfortune or bad luck upon something. In literature, an imprecative mood is often used, usually in a negative sense rather than a positive. (A more positive style would be the optative mood, wishing good luck upon something instead.) Author Stephen Crane does create an imprecative mood through much of The Red Badge of Courage, since the narrator often hopes for ill fortune to fall upon the enemy (and even his own officers) rather than wishing for good fortune to grace Henry's regiment. For example, in Chapter XI, Henry hopes for his own regiment to be defeated.
In a defeat there would be a roundabout vindication of himself. He thought it would prove, in a manner, that he had fled early because of his superior powers of perception.