Brendan fought alongside Zoltan many times. At one point Brendan became a leader of a company that followed him into battles. Unfortunately, they all died during the siege of Hattenburg and Brendan himself only barely survived. He blamed this military failure on commander Nargash who sent pikemen to capture walls without giving them any siege weapons. Brendan got his entire back scorched with hot oil that the defenders poured down from the walls, marking him for the rest of his life and causing that he could never again fight in the open field.
After this battle, he considered learning a new trade or joining some city guard as a sort of retirement. When Zoltan met him some time after the battle he was happy his friend survived and advised him to become a bouncer in Novigrad but Brendan rejected the idea, fearing the rise of anti-nonhuman sentiments in the city. Shortly after their camp was attacked by unknown archer and Zoltan accused him of not revealing some facts.