User blog comment:WitchKingofMorgul/Black Arrow theory/@comment-75.1.134.103-20130204000426

In The Hobbit didn't Smaug say that his underside was "unique" or something in the way that his underside was much thicker than a normal dragons. And that the White Council was concerned about Sauron possibly making an alliance with Smaug. In fact keeping Smaug busy (and maybe getting rid of him) was the whole point of Gandalf helping Thorin!