On November 22, 3001 3A, Móg, along with Thrugg and Grimbosh, was ordered by Saruman to lead an army of 20,000 Uruk-hai to march towards Helm's Deep where the people of Rohan have taken refuge. Upon arriving to the fortress at around nightfall, he lacked the unique helmet worn by other Uruk-hai commanders however, so it can be assumed he was a normal warrior. He stands on a huge boulder and roars, ordering the others to attack the fortress. After the first death of an Uruk-hai soldier, he stood on a rock without a helm roared at the host, meaning to attack the fortress. He leaped down from the rock and joined the charge, but was killed as soon as the Elven and Rohirrim archers started firing their arrows, killing him and many Uruk-hai that were reaching the fortress. After Thrugg was second to die by Aragorn, Grimbosh was left in charge to lead the Uruk-hai until dawn.