Like the Balrog, Smaug was too powerful for Sauron to dominate. Sauron might have made use of him, but likely would have had to wheel-and-deal with him as an equal.
While it's not confirmation, it shows that Gandalf fully believed the two would form an alliance. Although, what's more likely is that Sauron would trick Smaug into joining his army, as he had always been a master manipulator.
Smaug is aware of the return of Sauron, and was apparently intent on joining forces with him (although there was some amount of confusion as to whether the dragon's motives for an alliance with Sauron were).
It is later revealed that Smaug's attack on Erebor was all part of Sauron's design, meaning that Smaug and Sauron were in league with each other. Smaug was considered one of the highlights of the second film of the series; several critics hailed him as cinema's greatest dragon.
Gandalf's main reason for supporting Thorin's quest in The Hobbit was to eliminate the threat of the dragon Smaug, who would be a powerful ally for Sauron. Despite popular belief, the Balrog known as Durin's Bane was more powerful than Smaug in Middle-earth, being a literal, primordial demon.
Aragorn vs Sauron unreleased scene (better quality) - edited
Could Gandalf have beaten Smaug?
Although both the Balrog and Smaug are creatures of fire, and Gandalf is able to match them thanks to the power of his fire ring, defeating the Balrog takes far more spiritual prowess, which is why Gandalf is able to essentially 'level up' and comes back as Gandalf the White, whereas defeating such an immense physical ...
That title falls to Ancalagon the Black, the largest dragon ever to have existed in Middle-earth. He was bred by Morgoth during the First Age to fight for the Dark Lord during his campaign of terror.
Smaug's dragon-fine would not have been hot enough to destroy the One Ring. The malevolence that Sauron put inside of the Ring could only be destroyed in the Cracks of Doom, so Frodo was compelled to make the journey to Mordor.
Despite Smaug's great size, strength and Durable hide, Sauron's Dark Magic, Powerful Weaponry and Great Intelligence ultimately triumphed over Smaug. Sauron was immune to Smaug's fire as Sauron has control over fire and had adapted to it.
Described as a "long-worm", although this imprecise term seems to be more of an expression rather than a separate taxonomic group. Smaug — the last great dragon of Middle-earth, slain by Bard of Esgaroth.
Peter Jackson certainly makes the assertion in the theatrical and extended editions of the Hobbit movies that Smaug and Sauron are not only well aware of each other, but are planning to ally with each other.
Sauron was portrayed by Benedict Cumberbatch through voice and motion capture in The Hobbit: An Unexpected Journey, The Desolation of Smaug, and the upcoming The Battle of the Five Armies. Sauron is the overarching antagonist of the trilogy, given that he made a pact with Smaug and is Azog's boss and leader.
If Smaug had not conquered Erebor, the dwarf kingdom would not have been destroyed. This might seem like a good thing, but the long-term consequences would have been a disaster.
If he is using black arrow. The black arrow is just a normal arrow so that wouldn't have any effect. Bard only knew where to aim because he could understand the thrush that heard Bilbo talk about it. So Legolas would only be able to kill Smaug through sheer luck or he would have to see the gap in the gemstone armor.
Gandalf has proven himself to be one of the most powerful characters (and the most powerful wizard) in The Lord of the Rings franchise. Smaug may have been physically powerful and intelligent, but he would not have stood a chance against Gandalf if the wizard could use his powers equal to that of Smaug's strength.
There is no account of any dwarf ever killing a Balrog, let alone multiple. The only recorded instances of Balrogs having been slain are Gandalf's slay of Durin's Bane, Echtelion's slay of Gothmog and Glorfindel's slay of an unnamed Balrog.
The first Dark Lord was the rebel Vala first known as Melkor and then as Morgoth. Denied the demiurgic power he desired, he was consumed by a nihilistic purpose: the destruction of Middle-earth. The second Dark Lord was Morgoth's successor, the subversive Maia named Mairon, and later Sauron.
Sauron does not fear Durin's Bane because essentially they had been allies back “in the olden days". Both Balrogs (all balrogs) and Sauron chose to serve Melkor/Morgoth.
As a Valar, Morgoth led a whole slew of Balrogs in the First Age, but because Sauron was only a Maia, the Balrog would have had no loyalty to him. He was his own master in Moria, and no Dark Lord was going to ruin that.
No, Balrogs do not serve Sauron. Similar to Sauron, Balrogs are Maiar, powerful spiritual beings second only to the Valar themselves. They were corrupted by Melkor's evil before the first age and were made into Valaraukar (Demons of Power). They very strength and wills were bound to Melkor.
