The final film in Peter Jackson's Hobbit trilogy has been retitled The Hobbit: The Battle of the Five Armies.

The New Zealand film-maker made the announcement on his Facebook page following weeks of speculation surrounding the movie, which was previously titled There and Back Again. The third instalment of Jackson's adaptation of JRR Tolkien's book is due in cinemas this December. The Oscar-winning director said the change had been made because the old title no longer felt right for a trilogy, having been conceived back when the film-makers planned a two-part adaptation of the 1937 fantasy fable.

"There and Back Again felt like the right name for the second of a two films telling of the quest to reclaim Erebor, when Bilbo's arrival there, and departure, were both contained within the second film," wrote Jackson. "But with three movies, it suddenly felt misplaced - after all, Bilbo has already arrived 'there' in the Desolation of Smaug.

"When we did the premiere trip late last year, I had a quiet conversation with the studio about the idea of revisiting the title. We decided to keep an open mind until a cut of the film was ready to look at. We reached that point last week, and after viewing the movie, we all agreed there is now one title that feels completely appropriate. And so: The Hobbit: The Battle of the Five Armies it is."

Jackson said There and Back Again, which was Tolkien's own subtitle for The Hobbit, might re-emerge for a DVD box set at a future date. The Battle of Five Armies is a reference to the climactic battle at the end of The Hobbit in which dwarves, elves, men, goblins and giant eagles fight it out beneath the Lonely Mountain.

The first two films in the Hobbit trilogy have so far taken just under $2bn at the global box office. Jackson's previous fantasy trilogy, based on Tolkien's sequel The Lord of the Rings, took $2.89bn between 2001 and 2003.