Why destroy Laketown's bridge?

[Galendor]

Originally Posted by The Sixth Wizard

Smaug would not land on the bridge. He would land a sizeable distance (hundreds of metres) out from it, then approach it on land. Smaug would obviously not want to fly at speed into something so flimsy and close to the water. Walking across is a different matter, but he couldn't land on any part of Lake Town because of his velocity and flying style.

I'd say being so hot would have something to do with their flying ability. Smaug's treasure chamber is hot as I remember, and he could be "quenched" if he were to venture into the lake. A dragon's heat must be connected to its lifeforce/energy (cold blooded?) and would help it lift off the ground. And where in Tolkien's work do we find that Smaug has "relatively small wings"? It is only in his pictures, which, as we have already discussed, are not drawn entirely for accuracy. More for appeal.

I agree, and don't actually think Smaug flew like a hummingbird. He is a magical being, like a Balrog, and not subject to normal physical laws. The text seems to support that his assault on Laketown took the form of repeated long swooping passes (i.e. he could not hover).

The writing supports the notion that Smaug was quite large. When he realized someone (Bilbo) had stolen a piece of his treasure, he "shook the mountain roots" in his rage. When Smaug went looking for the thief, by his own testimony he ate six ponies. When he tried to blast Bilbo with fire as Bilbo escaped running up the secret passage, Bilbo was saved because Smaug's head could not fit into the passage, which was described earlier as being five feet high by three feet broad. So Smaug's head was more than three feet wide.

Considering his head size, Smaug was as big or bigger than a large elephant. That means on all fours he was probably over 12 feet tall at the shoulder and weighs over 7 tons. Despite this mass, he could move quickly on the ground, he could run on all fours. In the chapter "Inside Information" it says: "He thrust his head in vain at the little hole, and then coiling his length together, roaring like thunder underground, he sped from his deep lair through its main door, out into the huge passages of the mountain-palace and up towards the Front Gate."

Although the writing does not explicitly say it, I think Smaug did not want to attempt a landing in Laketown for reasons already pointed out - Laketown might not support his landing force. And Smaug clearly did not want to fall into the lake, as stated that might quench his fire and he did not want that to happen.

Although Tolkein does not explicitly write it, we are given the impression that Smaug is very large, unthinkably strong, fast, and invulnerable over most of his hide. I assume from the description that you certainly do not want to face him on the ground, he would roast you or rapidly run at you and crush you. Hundreds of men, elves, or dwarves could not face him on the ground and survive.

So my impression from reading the story is that by cutting the bridge, Laketown removed any possible way for Smaug to assault by land. It removed an attack option from him. And Smaug was too wise to attempt a landing in Laketown. He was big and flying fast, so his landing might break through the wooden docks (as it did when he fell from the sky in death). I also think it is within the scope of imagination to belive that the Laketowners had built in to the bridge design an ingenious (but admittedly undescribed) mechanism for rapidly dismantelling part of the bridge. There is an engineering solution to almost any construction problem.