Upgrading the Barracks will allow you to employ hirelings to defend your stronghold during attacks.
The heart of the garrison at Caed Nua - a potential one, at any rate.
Points of interest
- You need it to hire hirelings. It consist of a single room to the north of the front door of the keep. While there are a few things to look at, there is nothing significant to do there once the upgrade is complete.