The omniscient point of view used by Crane comes into play as Crane tells the reader how the other soldiers react to the wound — the reader and Henry being the only observers having knowledge of how he sustained the injury.
Fear — in this case, fear of the unknown — grows because Henry has not yet seen the enemy.
Henry, the inexperienced youth, can't judge how much truth is in the veterans' tales.
This lack of knowledge contributes to his fear, which he internalizes completely, leaving him isolated from the other men.
This move surprises the Union troops, including Henry, and his fears return.
Indeed, he becomes so afraid that he drops his rifle and runs as the enemy approaches. Crane uses the quick shifts in Henry's character from chapter to chapter to show Henry's unstable mental condition; his courage and commitment to duty don't come from within, but are entirely influenced by external forces which whip him from one extreme to the other.