Do you claim any relation to Kermit Smith who was b. about 1910 in Bear Creek, AL, was a veterinarian and is buried in the Bear Creek cemetery?He was married to my late aunt, the former Pauline Phillips.
I did not find your ancestor's name in the listing of men who fought in the First Alabama Cav. USA in Glenda Todd's book, "First Alabama Cavalry USA: Homage to Patriotism," Heritage Books, Inc.Her book has a lot of good information about the Union movement in NW Alabama.
Another book which is written as an historical novel is "Southerners in Blue: They Defied the Confederacy," Quarry Press, Dallas, TX, 2002.It focuses on Unionists who lived in both Marion and Winston counties.
You might find some more mentions about Mr. Nelson in Southern Claims Commission testimony.