Some of the best works on the subject are Shelby Foote's classic Civil War series and James McPherson's also classic Battle Cry of Freedom. Grant's autobiography delves into the subject a bit as do books like Lee's Lieutenants and South of Appomattox. There is information to be found in numerous biographies and autobiographies, but since these works focus on a specific individual, they are often skewed in their objectivity.
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