The card that shows his capture also says, "due to be released at Louisville". I believe Louisville was the port where it was determined what prison Confederates captured in the western theater would be sent to. Some chose and agreed to remain north of the Ohio river for the duration, but family men usually made a b-line for home at the first opportunity. I believe the Union 1st Tennessee Cavalry (from upper East Tennessee) was operating in the area of Cowan. I've always wondered if John may have been captured by someone he was acquainted with that "looked the other way" and maybe furnished an old worn-out nag and pointed him toward Sullivan County.