The key element is the character of Virgil Caine, the soldier in question. Virgil seems to be a low level guy working on supply lane between Danville and Richmond. Personally, he's suffered considerably. His brother had been killed in the war. Virgil's not fairing a whole lot better, as he describes himself and those around him as "hungry, just barely alive".
Virgil's a fairly simple guy. He comes from a line of farmers and it seems like its of the sustenance farming variety; he isn't above chopping wood for some extra cash. Virgil probably doesn't really stand to gain much from the war. It's basically impossible to assign a single cause to the Civil War, but whether you're in the slavery, states' rights, or tariffs camp the war isn't about improving life for Virgil. He's tied to the conflict merely because he's tied to the land.
Virgil's fucked. The only way to end his suffering will be that his side loses. And through all this, he's utterly powerless. The supply train he's on is continuously having its tracks torn up by the Union troops. The situation is perfectly futile. He's in a conflict where he can gain nothing, has already lost basically everything, and can't do anything. And it's playing out over and over again.
Pretty fucking sad.