Once you've killed Gathbin's guys in tavern and you return to Caed Nua, Marshal Forwyn waits in the main hall to inform you about Gathbin's preparations.
However, a couple of days later, a second Marshal Forwyn spawned outside of the tower, together with the scripted crowd that you can pay off earlier in the quest.
I've beat Gathbin's army, and the Marshal in the main hall is gone, but the one outside with the crowd remains, and while he has the same dialogue options as the other one, none of them do anything.
