What if??

[mormegil]

My first thought here is that Smaug's will is his own and would not be held under Sauron's sway because while Sauron is powerful he is no Morgoth and controlling a dragons is something I don't see possible especially without his ring.

Now as for an Eagle taking on a dragon there is no competition, a dragon is much greater.

[Farael]

but it'd make for an interesting story, as it is believed that the fire of the dragons could destroy the Ring!!

I don't believe either that Sauron could control the will of a Dragon, yet it is possible that they could work together, trying to outsmart each other yet moving towards the same goal in the beginning. Something along the lines of destroying the oposittion first and then they'd probably kill each other. After all we should consider that Smaug fell of a single (Well placed) arrow and Sauron could probably defeat him if caught of guard, but Smaug would be too smart to be easily tricked.

[the phantom]

My first thought here is that Smaug's will is his own and would not be held under Sauron's sway...

I'm not so sure.

Gandalf says this in UT, The Quest of Erebor-

The Dragon Sauron might use with terrible effect. Often I said to myself: 'I must find some means of dealing with Smaug.'

Gandalf thought Sauron would be able to "use" Smaug.

[mormegil]

I see your point but Sauron also thought he used Shelob but he didn't control her, so my point remains valid if it is seen that Smaug is his own master. Using a creature like that can be unpredictable.

[Fingolfin II]

I'm inclined to agree with mormegil here. While, as the phantom points out with that quote from UT, Smaug could be used by Sauron, the control Sauron would have over him IMHO would be very limited- like Shelob, as astutely pointed out by morm.

I suppose the same thing may be said of the Balrog of Khazad-Dum also; if Sauron tried to persuade Smaug or the Balrog to his service, they would probably start out by following his instructions, yet Smaug's desire for gold and riches and the Balrog's desire to....kill....would in the end overcome their 'servitude' to Sauron and they would serve only themselves, destroying for pleasure. Not that this is totally out of line with Sauron's desires- only they probably wouldn't completely obey all his desires.

[Voralphion]

Now as for an Eagle taking on a dragon there is no competition, a dragon is much greater

Actually the eagles fought the winged dragons in the War of Wrath, so I think it is entirely possible that the eagles would be able to fight with a dragon, maybe not one on one but certainly with a group of them.

I don't think Sauron would have been able to completely control Smaug even with the ring, but they certainly would have come to an agreement and worked together, with Sauron perhaps allowing Smaug to control some land in the north, as there Smaug could have destroyed the last elven realms there such as Rivendell.

[Eomer of the Rohirrim]

Yes, the Eagles would have been greater in those days but they could probably challenge Smaug if they fought together.

I don't think Smaug's fire would have been hot enough to destroy the One Ring (if any Dragon's fire ever could have).

Was the initial post asking what would have happened at the Black Gate? If so, more Eagles would have died (possibly) but it would have had no effect on Frodo's quest. Unless Sauron convinced Smaug to guard Mount Doom. That could be an idea.