Scenario setup: Territory with a port has two land units and three ships in port. An attacker defeats the land units. They can only retreat to an area that already has one land unit. The losing player's supply limit means only one army of three. Which happens first: The ships in port are destroyed (or become the attacker's), or the land units retreat? If the former, the retreating player keeps all of their retreating units. If the latter, one of them is destroyed. This came up in a game yesterday when I attacked Lannisport as Greyjoy. Poor guy was getting bashed from all sides so we let him keep all three land units, though it makes more sense to me that the losing player must retreat before the attacker takes control of the territory and thus destroys the ships in port.

The rules state that the attacking player (if he wins) immediately takes control of the ships in port. I would read this as, the moment that the victor is determined, which is before the retreating phase. The argument would not be hard to make that it should be after combat is completely finished though.

Probably not the clear answer that you were hoping for.

Actually the Rules say that taking the ships in Port only happens after the Attacker has "taken control" of the area (Page 25) -- which happens during Step 4 of Combat Resolution (Page 20 & 21), right after Step 3 (Retreats and Routing).

Land Units are Retreated/Routed first -- then ships are taken or destroyed.

kauai,

Can you point me to the spot that directly states that is when the attacker takes control of the area? I don't see anywhere in the combat resolution where it says when the attacker officially takes control, so I assumed immediately when he is determined the victor is when he takes control of the territory.

Page 21:

4. Combat Cleanup

If the combat was won by the attacker, remove any Order token the
defender had assigned to the embattled area (if one remains) as well
as any Power token in the area (which would exist if the defending
player had previously established control there, see page 24).

If your Power token is there, you still control the area (even if you have no units there). Once your Power token is gone, you lose control.

Also in the FAQ, Page 3:

Q: At what point does the winner of a combat
exert control over the embattled area?

A: Control over an area does not change hands
until all stages of combat are completed. In the case
of a completely emptied area, at no point of time
during the combat would the area be considered
controlled by the attacker (and so would not count
towards his victory condition).