My ancestor was a Naval Landsman in the Civil War. I'm still trying to research what that entails, but can anyone tell me what the Naval Service detail means?

"Potomac, Varina, Oneida, Ohio Sabine North Carolina"

I know that Potomac is a River near DC, and Oneida is a town in NY State, and that Sabine Pass was a Confederate victory in TX. But these don't all look like battle sites, just general locations.