What are the main four plot points in section XIX -XXI of Beowulf?

In sections XIX-XXI of Beowulf, the main plot points are: Beowulf prepares to fight the dragon to protect his people, he faces the dragon alone as his warriors retreat in fear, Beowulf's sWord fails him in battle, and Wiglaf comes to his aid, helping Beowulf defeat the dragon but also getting wounded in the process.