The correct answer to this open question is the following.
In "the battle with the dragon," the dragon keeps the treasure it steals in the cave or its lair. The dragon dwells in a cave.
The reference is to the story of Beowulf. In the final act, Beowulf fights against a big dragon. Indeed, the dragon is the third creature Beowulf confronts in the story. This is the result of a robbery. A slave steals a jewel, a precious cup from the Dragon’s lair. The Dragon burns the towns and that is when Beowulf decides to face the creature and kill it.