What whould be cool is to like, do a "king of the hills" game.
Simple rules. We split the garrison into 8 sections. One in each corner of the garrison and on two floors, Roof and main halls.
Divide the Militia into 8 teams and let them barricade thier part as much as possible and have the lich king attack. It whould be fun RP and a good chance too cractice both dueling and roll fighting ( if there is a too great level diffrance )
This even could come along with the Lich kings attack. The cult gets heavly reienficed by a large number of undeads an spot their chance too invade thier number one enemie in a full frontal attack.
If the Militia are too win, then congrats, we are superior then the Cult. Or if the Cult win the militia have too move out too a small settelment of Tents 'till they regroup and take over it again (Maybe automaticly after a few days) Or just arrange the event that the Militia will win in the end.
I always wanted too see a large battle in the garrison, burning walls, falled soldiers, dead cultists and an endless bloodshed in there.