No, the McCune born in 1916 would have been 49 at the end of the War. I was speaking of the younger man, born in 1848. Fortunately, Texas was not invaded on a scale in comparison to any of the other Confederate States. Men of his age in Texas were never compelled or actively conscripted to the Confederate Army. Don't assume this is the same man. You mentioned another James McCune, but did not give his birth date. If this is the elder James, then he would be exceptional indeed.

You have a lot of research ahead of you. A good place to start is to obtain his NARA military record. You can do that through the advertisements on this message board.