Courage Comes in Casks
My quartermaster tells me that our stock of ale casks has gotten low. Get coin from him and acquire me more casks of ale so that we may toast our victories in the field appropriately..
Once you have taken this quest you'll be compensated with enough denars to buy the required casks and be granted permission to leave the army. These casks should normally be acquired through trading with the merchants, but you can obtain them through raiding if a village has them. There is no limitation on how they are obtained.
Once you have sufficient casks in your inventory the quest will update and notify you to merge back into the Oathbound Lord's army for completion.