My earlier statement was, ""Near Atlanta" does not necessarily connect to Action at Camp Creek GA, Aug 18, 1864."
Certainly this man's regiment was under fire almost every day during August 1864, although not involved in an actual battle or recorded engagement. Routine picket and artillery fire along the lines caused casualties almost every day.

Here's my guess about how this mistake was made:
A family researcher came across information not available to you giving date of death as Aug 18, 1864. Assuming this man's death must have been the result of a recorded military action in the Atlanta area, the researcher identified "Combat at Camp Creek" on this date. Of course it immediately qualified, and no further questions were asked. Not until now, anyway.

Until you can locate real information, it's probably best to investigate and confirm all of this.

On a personal note, if I was ever so foolish as to add similar unsourced/unconfirmed information to my wife's family tree, there would be combat in my home or wherever she happened to locate me.