How did Tolkien have so much happen in such a short book?

[Michael Targaryen]

Some thousand page novels don’t have as much happening as in the Hobbit.
How did Tolkien accomplish such a feat?

[Will]

Um ... by putting in lots of action?

Something he then forgot to do with the first 100 pages or so of Lord of the Rings.

But seriously ... he wrote the Hobbit as a child's story. That meant a relatively simple plot with little character development or back story. And to keep the attention of children he put in lots of incidents.

He was also following the precedents of his scholarly study into Arthurian literature, which was also relatively long on action and short on character.

[Lindsay]

When I heard that they were making three films out of The Hobbit I thought it was absolutely ridiculous when you look at the size of the book, but that was before I read it myself, and now I can see that it's quite justified!