Jim --

This was a state unit enlisted for short-term (six months or less) duty. That's why it may not be mentioned in the OR. You should be able to locate something about the battery at the Georgia State Archives. For that matter, this man's service file ought to have some information about where he was and what he might have been doing.

A Confederate battery was entitled to have an assistant surgeon on staff; not sure what the rules were for Georgia state units. Dugger appears on roll as a private only, but could have doctored anyone who needed his assistance.

You might notice that Dugger appears with other Georgia units, some of them being State Guard units. He may have been with other units before and after he belonged to Pruden's Georgia State Battery. Here's the NPS link to check this name:

http://www.itd.nps.gov/cwss/soldiers.htm

Since Dugger was a physician, he would've been exempt from Confederate and state militia duties. That of course means he enlisted as a volunteer.