Henry's regiment was supposed to have served in this battle as reinforcements. But now, with the front line gone, they hurriedly get ready for the enemy's charge, fumbling awkwardly with cartridges of ammunition. Henry feels startled and stupefied.
The soldiers' lack of any battle experience shows up in their physical clumsiness. This foreshadows the officer's insulting comments in chapter 18.
The screaming mob of enemies approaches through the trees. Without waiting, Henry fires a first wild shot. As his regiment starts blazing away, Henry's individual anxieties disappear: he feels like a cog in a machine, or part of a "mysterious fraternity." Henry gets furious with the oppressive battle smoke. He fires and loads automatically without stopping.
The lieutenant collars a soldier trying to run away and beats him back into line. Henry sees several soldiers get shot, their faces looking betrayed, their bodies dropping into awkward poses as if they'd fallen from the sky.
Henry's regiment repels the enemy charge. Gunfire gives way to the regiment's triumphant cheers. The soldiers grin at each other in congratulations. Henry feels like he's just worked a hellish day in a factory.
The soldiers need each other like fellow workers on an assembly line. The work is not glamorous, but they all appreciate a job well done.
Henry watches the scene around him. A battery of artillery guns is lobbing shells overhead. The Union battle flag flies again over distant troops. And to Henry's astonishment, the sun shines brightly in the blue sky above.
The mood of battle is not reflected in the landscape. It might be hellish for Henry, but it's just another sunny day for mother Nature, indifferent to human strife.