I'm thinking that, given the usual Heortling preference for mobility
and ambush, there would be several hero bands always working outside
the walls to disrupt lunar supply lines, harass foraging parties,
kill messengers, and the like. This also gives the defenders a way
to use allies that don't relish being trapped inside Whitewall, or
who have only mustered out for a season. And when they leave, they
tell stories of the bravery of the defenders, which spread further.
I have one hero band in mind. I might write it up.