Battle of the Five Armies:

The Battle of the Five Armies occurred in 2941 of the Third Age. This battle began between the Dwarves on one side and the Wood-Elves and the Men of Lake-Town on the other. The Men of Lake-Town and the King of the Wood-Elves demanded a portion of the spoils of the Lonely Mountain after the death of Smaug, and Thorin refused them. At that time there were only the thirteen dwarves from the quest of Erebor. Thorin sent a message by raven to his cousin Dain in the Iron Hills. Several days later they arrived and seeing the siege, attacked the Men and Elves. Gandalf appeared in the middle of things and forced a truce, during which he informed them of the approaching army of Orcs and wargs. The Men, Dwarves and Elves allied against the Orcs, but even so they were greatly outnumbered. Then the Eagles arrived, as did Bëorn. These brought victory against the Orcs. However, Thorin, Fíli and Kíli died in the battle.
The full record of this battle is given by Bilbo in the Hobbit, the diary of his journey with the Dwarves.