Shelby Foote's massive three-volume narrative history of the Civil War is one of the glories of American letters.
You can buy the paperback edition here:
The set is also available in hardback but recent printings are no longer bound in sewn signatures — for a definitive version,
it's worth tracking down one of the earlier hardback editions.
also recorded two sections of the work as audiobooks, and it's wonderful to
hear him read this great prose in his classic Mississippi storyteller's
drawl. The Beleaguered City, covering the Vicksburg campaign, and The Stars In Their Courses, covering the Gettysburg campaign, are both out of print but can sometimes be found through online sellers.