Would you be referring to John Maupin Black b: 5 Dec 1830 Calloway MO, d: 20 Feb 1907 Jackson Oregon? His wife wrote a diary which has been published about the trip on the Overland Route and Oregon Trail the family made in 1865.(ISBN 0-936738-36-7) He has a Civil War draft record in July 1863 from Calloway county that lists him as a nonresident and living in Salt River Twsp Audrain County. That matches his 1860 census listing. His Oath of Allegiance done 5 Februaury 1865 is here: https://www.fold3.com/image/280144298
I find no military service for him.
He was a slave holder. See Marguerite Black's introduction and Bio of J M Black here:
This indicates the family was not banished but following other extended family to the opportunity of the West.