The little boy has been playing at soldiers out in the woods. In the meantime, a bloody battle, the battle of the title, has been raging all around him. Yet he remains blissfully unaware of this as he attacks invisible foes in the forest with his little wooden sword.

However, once a real-life foe appears on the horizon—in the shape of a rabbit, no less—then the boy suddenly gets scared. So long as he was in the land of make-believe, everything was just fine. But the sudden appearance of a rabbit has broken the spell. This foreshadows the terrible moment later on in the story when the little boy will return home to find his mother dead and their plantation destroyed.

But before then, the little boy is so disturbed by his encounter with the rabbit that he starts crying. In fact, he cries so much that he actually ends up crying himself to sleep. In the meantime, the Battle of Chickamauga, one of the most brutal battles of a particularly brutal war, rages not far from where he lies asleep between two rocks by a stream. But the little boy remains completely undisturbed by any of this. As he's deaf, he can't hear a thing.

In "Chickamauga," it may seem unrealistic that he was able to sleep through a battle going on all around him. What fact, revealed near the end, might explain how that was possible?

In Ambrose Bierce's short story "Chickamauga," a little boy wanders into a Civil War battle while he is pretending to be a soldier. The little boy feels terrified as he wanders through the woods; he cannot find his way home and, exhausted, eventually falls asleep. 

Hours later, the child wakes up and sees injured men dragging themselves on the ground. The child has heard nothing during his time in the woods. Thousands of men have passed through the woods during the course of the battle. The story presents some horrific scenes of men suffering and dying around the child, but he does not seem to understand what is happening. The narrator relates that it was a "merry spectacle" for the child. 

Near the end of the story, the little boy follows a glowing red light and discovers several burning buildings. Only after dancing joyfully in the flames does he see the body of a dead woman - his mother - and recognize the fiery buildings as his home. 

Here we finally learn the reason behind the boy's strange behavior during the story - he is deaf and mute. He cries aloud - "a startling, soulless, unholy sound, the language of a devil." Because he was unable to hear the battle raging around him or to hear the cries of his family, he remains oblivious to what is happening until the very end of the story.