James M. Campbell has a military service file with Co. "I", 6^th Tennessee Cavalry Regiment, a Confederate miiltary organization.

http://www.tngennet.org/civilwar/csacav/csawheeler.html

"It was known in the field, all muster rolls made out as, and paroled as 1st (Wheeler's) Tennessee Cavalry Regiment. However, the Adjutant and Inspector General's Office, on September 12, 1862 ordered that it be known as the 6th Tennessee Cavalry Regiment, as there were already rolls on file for one 1st Tennessee Cavalry Regiment."

This is the right man. Copies of his military service files are available here --