1. American Civil War Guerrillas: Changing the Rules of Warfare by Daniel Sutherland (Praeger, 2013).
Sutherland champions the idea that the irregular war, far from being a mere adjunct of or distraction from the conventional fighting, had a tremendous impact on the conduct and results of the Civil War. From the description, it appears this new book revisits many of the ideas raised and developed in Sutherland's earlier A Savage Conflict.
2. Union Infantryman vs Confederate Infantryman: Eastern Theater 1861-65 by Ron Field (Osprey, 2013).
Part of Osprey's Combat series, the book examines the character of Civil War action at a small scale, using situations drawn from First Bull Run, Spotsylvania, and Chaffin's Farm.
3. Smithsonian Civil War: Inside the National Collection edited by Neil Kagan and Stephen Hyslop (Smithsonian Books, 2013).
A pictorial history of over 500 objects from the Smithsonian's Civil War collection.