The August 2, 1940 issue of the Dexter Statesman [Dexter, Missouri] published a photo of “Uncle” George Fox and Francis M. Snider , the last two surviving Civil War soldiers in Southeast, Missouri and noting that with the recent passing of Fox, Snider was the last surviving Civil War veteran in the Southeast Missouri district.
Last of Southeast Missouri Civil War Veterans. 02 Aug 1940, Fri The Dexter Statesman (Dexter, Missouri) Newspapers.com
However, the paper did not reveal the two veterans loyalty during the war. I was able to find the information on a webpage that listed attendees of the 1938 Veterans Reunion held at Gettysburg, Pa. , remarkably both Fox and Snider both attended the event and were listed as serving in the Union Army.