[Archaic Elf]

Originally Posted by Pitchwife

Smaug himself might be sufficiently interested in Bilbo for goblet-thieving and being a sneaky annoyance to go after him, but he wouldn't have known where Bilbo came from (except presumably somewhere west of the Misty Mountains, from what Bilbo told him in his riddles), and I don't see him inquiring for directions to the Shire like the Black Riders did, so the Shire might have been safe, for a while at least.

The thought of Smaug wanting to get revenge on Bilbo helped inspire the thought of Smaug torching the Shire. It would present a very ghastly visual of innocent hobbits caught in an air raid...perhaps that's a little too WWII...

Originally Posted by Pitchwife

If Sauron would have controlled Smaug somehow, I doubt he would have sent him for the Ring instead of the Nazgûl, knowing how possessive dragons tend to get about treasures. But he certainly could have used Smaug to attack his other enemies - Thranduil probably first, then Lórien, possibly Rivendell, maybe even Gondor and Rohan. Like Tolkien says in LotR Appendix A III (Gandalf speaking):

Yeah, it would be a very bad idea for Smaug to go after the ring. Dragons fire can destroy it, so Sauron wouldn't want any unfortunate accidents, like Frodo getting caught in a blast while wearing the ring.

I am assuming that Smaug would form an alliance with Sauron. Glaurong was a willing helper of Morgoth, but Glaurong did seal himself up in Nargothrond with all the wealth once he sacked the fortress with the help of the orcs. I think Smaug would be the same way...help out Sauron for some profit, and then retire from action when he's satisfied or his own purposes are met. Smaug would likely want to keep his realm secure and possibly finish off Bilbo (or at least make an example out of a few random hobbits). Once those two goals are met, Smaug would probably return to the lonely mountain.

Originally Posted by Legate of Amon Lanc

I think the idea was that Sauron would eventually recruit Smaug to his cause and use him as a vanguard of his army which would allow the Easterlings (not hindered by the Men of Dale and the Dwarves of Erebor) to pass through the Grey Mountain narrows, cross the Anduin close to its beginning (where it was still possible) and pass the mountains to Eriador - resp. retake Angmar and basically re-launch the Angmarian campaign all over again. All the other things mentioning that subject seem to point towards this direction (and I have been looking into this topic rather deeply, actually, as I used to be interested in it a lot).

Smaug would have been a major player in the War of the Ring, like the Witch King and Saruman. Even if Smaug had already wiped out the men of Dale, Smaug's position put him at odds with the elves of Mirkwood and the dwarves of the Iron Hills. He would still have enemies, so working with Sauron to allow passage of the Easterlings seems like a good idea on his part.