I would recommend these three books.
Oliver P. Temple, East Tennessee and the Civil War (Cincinnati: Ayer Company Publishers, reproduction of 1899 edition), an eyewitness account of the strife in East Tennessee; Paul D. Escott, After Secession: Jefferson Davis and the Failure of Confederate Nationalism (Baton Rouge: Louisiana State University Press, 1978), the most thorough recent book about the internal dissent among the Confederates; and Phillip Paludan, Victims: A True Story of the Civil War (Knoxville: University of Tennessee Press, 1981), a dramatic account of the pro-Union Confederates who were shot in East Tennessee.