by lomn
On a related note, because this has come up before and can play a fairly substantial role:An HQ with no troops is not controlled by any player, and so it does not count as a Red Star for any player. Any player can expand into its space (treat it as "unoccupied", even though the territory is technically "occupied but uncontrolled"), but would have to lose troops if there is also a city in that space, etc, and does not get to draw a resource card for occupying that space (it wasn't conquest). A player rejoining the war cannot place his troops in that space, even if he's the original owner, because the space is occupied.