I recall reading that eastern Tennessee was made up of small farmers living in a hilly/mountainous area; while western Tennessee (the flat land near the Mississippi River) was the cotton plantation area. Few slaves in the eastern part and much more in the western part. This produced totally different feelings about slavery and the war.
By the way, the nickname of "Volunteer State" for Tennessee comes from the
War with Mexico during which Tennessee provided a large number of volunteers for the US army.
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I recall reading this while visiting the Tennessee State history museum in Nashville.