How about this- On April 24, 1865 Col. Joseph Parsons of the 9th Tennessee Cavalry was ordered to turn over command of Camp Cantonment Springs and resume command of his regiment to prepare to move . At that time the 9th was located at Boyd Ferry. Next day (the 25th) the 9th was ordered to move to from Boyd Ferry to Rogersville Junction.

This would suggest that Cantonment was located at Boyd Ferry, later apparently known as Boyd bridge and located near what is now Boyd Island just north from the junction of the Holston and French Broad rivers.

Not much help but all I could find.