Aurvandil's might, fully mobilized and ready, is lesser than the 'moot's might, unprepared and unmobilized.
I don't expect to require a miracle at all, though indeed Barca's gonna bleed some.
That would imply Aurvandil has brought it's full might to bear, and not instead, left a considerable chunk at home. We don't need to send our full mobile army to deal with Barca, that would just be needlessly expensive in terms of equipment repair.
