The Bloody Ground by Bernard Cornwell

The Bloody Ground (The Starbuck Chronicles, Book 4) - This story of “the bloodiest single day in the Civil War” is the most attention getting story in this series so far.  General Faulconer, demoted to the War department has finagled Nathaniel Starbuck into a humiliating position, commander of the Yellowlegs.  The Yellowlegs were a battalion that was rumored to have run in the face of battle.  Adam Faulconer is at the Northern War Department waiting for contact from a spy in the southern ranks.