This article is from the U.S. Civil War FAQ, by Justin M. Sanders firstname.lastname@example.org with numerous contributions by others.
Ambrose Bierce, In the Midst Of Life.
A collection of short stories: the first half of the book is stories
of soldiers in the War. His themes are (1) the nature of courage; (2)
the ghastliness of war; (3) fighting between family members. Sort of "All
Quiet on the Western Front" for the ACW.
Stephen Crane, The Red Badge of Courage. 1891.
The most literary novel to emerge from the Civil War. It is a loose
description of the battle of Chancellorsville, although it doesn't say so.
It's about three Union enlisted men, and their motivations for fighting
Michael Shaara, Killer Angels. 1974.
A novelized version of the Gettysburg campaign, told from the
viewpoints of Lee, Longstreet, and Joshua L. Chamberlain, colonel of the
20th Maine. A must-read for those who want to know what it was like to be
Irene Hunt, Across Five Aprils.
A novelized account of a family living in Southern Illinois which has
sons fighting on both sides of the war. Written for children about ages
ten to twelve, but a good read for adults as well.