Book Chancellorsville Chancellorsville

Covers the events from Hooker replacing Burnside through the entire Chancellorsville battle. Some will consider it a Hooker apologia, but I think it does a effective job of explaining the many factors contributing to Union defeat: Hooker's concussion, mistakes by other generals, communication issues, Union strength on paper being misleading due to expiring enlistments, etc.

Not the definitive work on the campaign, but a very good read.