Tom is sitting on top of the Civil War cannon in the courthouse square, pretending to kill Doug. Doug pretends to die,
then lies on the ground looking thoughtful, like Doug does.
Tom says, "You look like you're going to get out the old pencil any second now," because Tom is awesome and says funny things right after sad chapters when we really need them.
Doug's morose about Colonel Freeleigh's death. He's also morose about Ching Ling Soo dying in Colonel Freeleigh's story, and about all the people who died in the Civil War, and about death in general, because he's Doug, and he worries.
Doug says, "I never dreamed so many people could die so fast, Tom," and we realize once again that this book is Bradbury's attempt to come to terms with his own mortality.
Tom tells Doug he needs to go write all this down, but he's being sarcastic—he actually wants Doug to stop being so emo and keep playing Civil War.
But Doug gets up and starts walking away, because he takes Tom seriously. Tom keeps yelling, "BOOM!" from atop the cannon, and yells after Doug that he just killed him three times.
Doug doesn't listen, so Tom just stays on top of the cannon pretending to shoot invisible stuff.