Answer:
Beowulf had gone to help King Hrothgar of the Danes to defeat a monster called Grendel who had tormented the kingdom for a long time. He defeated the monster with his bare hands after he discovered his weapons had no effect on him.
Shortly after defeating Grendel the monster, his mother comes for revenge and Beowulf goes after her and also defeats her, but it was an epic battle. After helping the Danes, he was rewarded with a lot of gifts and he went back home to Geats as a hero and was subsequently made their King.
Fifty years later, Beowulf is called to action again and defeats a dragon who mortally wounds him, he dies, is cremated, and a statue is erected for him by the sea.
Beowulf might have failed in his role as King by fighting the dragon because, with his death, his kingdom was defenceless against attacks and possible invasion.