During the Battle of Castle Black, Hill takes part in defending the Wall against Mance Rayder's forces. When Castle Black's inner gate is threatened by the giantMag Mar Tun Doh Weg, he accompanies Grenn, Cooper, and other black brothers to defend it. Although he initially wavers and considers fleeing upon seeing the Giant, he is convinced by Grenn to stay and fulfill his oath to the Night's Watch. They successfully kill the giant, but all of the black brothers are slain in the process. Their bodies are discovered by Jon Snow and Samwell Tarly after the battle. After the arrival of Stannis Baratheon and his forces, though not seen Donnel is among the numerous bodies of fallen black brothers burned in Castle Black's courtyard.
Donnel is one of the four brothers who, at Jon's command, shoot arrows at Mance Rayder (actually, it is Lord of Bones in disguise) while he is executed by burning, in order to grant him a quick and painless death.