Moosezilla
Grognard Warlord
Yeah, thank you T. "I don't know nuttin'!" again
Or if it's a Barbarian entering the same tile as your Def.0/Hidden Nat. unit, then you lose it too.No, it's not captured. Both units are overlaid and you remain in command of it. Unless it's on a city tile (or airfield or plane carrier) in which case, so sorry, you're screwed and you lose it.
So it'd be nice if we could switch the order of the civs somehow.