It has only been in the past 10-15 years that scholarly work has begun on the war in Appalachia. East Tennessee, Eastern Kentucky, what became West Virginia, West North Carolina, North Georgia, and Alabama had significant numbers of Unionist or those who did not support the war. This area of Civil War historiography has long been neglected and only until recently been explored other than local accounts that have not made it past the local archives or libraries. The war in Appalachia was not pretty and lots of bad things happened on both sides and nothing that historians of the "Lost Cause" era or those up until recent years wanted to talk about. This is the same issue with postbellum writing on the Western Theater and the Army of Tennessee. Much more chic to talk about Lee, Jackson, Stuart, and the Army of Northern Virginia.
Below are two books that could get you started.
Mountain Rebel: East Tennessee Rebels 1860-1870, by W. Todd Groce.
War at Every Door: Partisan Politics and Guerrilla Violence in East Tennessee, 1860-1869 by Noel C. Fisher.
Respectfully,
Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment