Why was Dale rebuilt?

Question

Why was Dale (the city ruined ages ago by the dragon Smaug), featured in Tolkien's The Hobbit, rebuilt after the events of the aforementioned story?

As far as I can remember, the dragon laid not only the city to waste, but its surrounding area as well. Why rebuild a city around which there's no life? AFAIK Smaug hasn't left the mountain for long, long years, yet neither flora nor fauna have really returned even by the time the dwarves got there. Why would life return after the dragon's fall?

I'd prefer an official answer, if possible: something quoted from Tolkien himself. (But clever guesswork is okay too, should we lack the previous.)

Answer 1

I don't believe there are canon sources for why it was rebuilt.

It's pretty easy to see why though.

The original purpose of Dale was to act as a trading nexus between the Dwarves and Men. Having a friendly town of men nearby would appeal to the suspicious and clannish dwarves.

The desolation of Smaug was no doubt mainly a result of the destruction and lack of maintenance of irrigation channels and infrastructure from the River Running. That would be relatively easy to re-instate after the Dragon was disposed of. Once irrigated dry land farming was started, this would have provided a source of food for the region and encouraged local settlements along the River. Key crops would have included wheat, Shiraz type grapes, citrus farming and maybe limited rice production, similar to the agriculture around the Murray River in Australia.

Finally, the town is very strategic, protecting the flank of the Dwarves and making a siege of the mountain more difficult to undertake without first disposing of Dale. By contrast the settlement at Esgaroth is too far away to be strategically significant.

No doubt, the Dwarves provided suitable trade concessions and other inducements to secure such a valuable strategic resource. Good relations with Dale (and the Elves of Mirkwood) would have been a key foreign policy objective of the Dwarves, as Thorin realised belatedly before his death.

Answer 2

Dwarves of Erebor / the Lonely Mountain along with the men of Dale ended up helping divide Sauron's forces by fighting Easterlings to the north.

This was actually by "design" of Gandalf, with the aim of splitting up Sauron's forces:

So it was that when the War came at last the main assault was turned southwards; yet even so with his far-stretched right hand Sauron might have done great evil in the North, if King Dáin and King Brand had not stood in his path.

... (the following is all from Appendices in Return of the King):

'I grieved at the fall of Thorin,' said Gandalf; 'and now we hear that Dáin has fallen, fighting in Dale again, even while we fought here. I should call that a heavy loss, if it was not a wonder rather that in his great age he could still wield his axe as mightily as they say that he did, standing over the body of King Brand before the Gate of Erebor until the darkness fell.

'Yet things might have gone far otherwise and far worse. When you think of the great Battle of the Pelennor, do not forget the battles in Dale and the valour of Durin's Folk. Think of what might have been. Dragon-fire and savage swords in Eriador, night in Rivendell. There might be no Queen in Gondor. We might now hope to return from the victory here only to ruin and ash. But that has been averted - because I met Thorin Oakenshield one evening on the edge of spring in Bree. A chance-meeting, as we say in Middle-earth.'

Answer 3

It became a hospitable region after the fall of the dragon "Bard had rebuilt the town in Dale and men had gathered to him from the Lake and from the South and West, and all the valley had become tilled again and rich, and the desolation now filled with birds and blossoms in spring and fruit in autumn" The last page of The Hobbit

Answer 4

I think they rebuilt Dale in that location for a couple reasons.

1. Dale may have been ruined by Smaug but most of the buildings were intact or had minor damage. Why build a completely new city somewhere else when an existing city just needed repairs.
2. Once Smaug died, there was nobody left to burn the region. So life was able to return after a while. The desolation of Smaug can be compared to a place after a wildfire. Life would return.
3. The #1 trading partner of Dale was the dwarves. Why not build Dale in front of the gates of Erebor? Erebor also relied on Dale greatly for food, supplies, and things that couldn't be found in a mountain. So why travel farther (say Erebor to Esgaroth) to get supplies, when you could walk across the land between Dale and Erebor, buy something and walk back in 2 hours. A reason unknown to the laketowners who rebuild Dale would be that Gandalf saw the upcoming war (War of the Ring) and attempted to create another front which would be Dale and Erebor for Sauron to fight.

I think these are good guesses for why Dale was rebuilt other than it all adds together into a great story.