The Killer Angels by Michael Shaara

They had stripped the rails from both sides of the road, to widen the passage, and some of the men were marching in the fields.

The road was already going to dust and the dust was rising, and there was nothing to see ahead but troops in the dust toiling upward toward the crest of a divide. The bands played as he went by. He nodded, touching his cap, head cocked, listening, searching beyond the music and the noise of rolling wagons and steely clinking of sabers and guns for the distant roll of artillery which was always there, beyond the hills. They came to a narrow pass: rocky country, dark gorges, heavily wooded. He thought: if there is a repulse, this will be good country to defend. Longstreet could bring up his people and hold this place and we would shelter the army back in the mountains.