This account of the destruction of Lake-town, the town of men, emphasizes the formidable power of Smaug, against whom even human beings are powerless. Bard appears for the first time and successfully kills the dragon by shooting an arrow into the same weak spot under his left breast that Bilbo observed earlier. It is interesting that Bard receives advice on this matter from a thrush; a thrush was the creature that reminded Bilbo of Durin's Day and allowed the dwarves to unlock the secret opening to Smaug's lair.
There is the suggestion here of the groups that will converge in the Battle of Five Armies, as the Master of Lake-town reminds his people of their enemies, the dwarves, and the Elvenking enters Lake-town to aid in the recovery from Smaug's devastation.
