what mood is left for the youth and the reader at the end of the chapter? how is this achieved

The mood is chaotic and frightening at the end of this chapter. Under the din of smoke soldiers run in terror. The youth is conjuring enough courage to just see the monster which is his enemy. Then the youth thinks he will likely run like the rest of the men.

Crane uses the metaphor of a monster to describe the violence of both the enemy and the battle itself. There is yet a little courage in Henry to see this carnage but the chaos and terror will envelope him as it has the other men.