In the year TA 2746, Thorin II was born to Dwarven prince Thrain II in the mountain city of The Lonely Mountain. Early in his youth, he and the other Dwarves of the Lonely Mountain were forced to flee by the dragon Smaug inTA 2770. During the exile, he quickly grew to become a capable warrior. This was demonstrated when he participated in the Battle of Azanulbizar in TA 2799. He marched with one of the Dwarven armies beneath the East-gate of Moria. At some point in the fighting, his shield broke, and using an oaken tree branch found on the floor as a shield, he gained the epithet "Oakenshield," which would remain with him even in death.^[2]

Thorin eventually became King-in-Exile of Durin's Folk after his father went missing, and presumably died in the dungeons of Dol Guldur.

Quest for the Lonely Mountain

Thorin with his sword, Orcrist

In TA 2941, after receiving a map his father had drawn for him and following advice from Gandalf the Grey, he took a contingent ofTwelve Dwarves to visit Bilbo Baggins in order to hire him as a burglar for their cause. Thorin's intent was to infiltrate the Lonely Mountain and steal back the treasure from Smaug.^[3]

The Dwarves, Bilbo, and Gandalf experienced a number of dangers on their journey to the Lonely Mountain, surviving Trolls, Orcs, Wargs, and Spiders. He found the legendary sword, Orcrist, in a troll-hoard along with Glamdring.^[4] In Rivendell, the Company rested and Elrond translated the moon runes in Thror's Map.^[5]During their journey through Mirkwood, Thorin and his Company encountered spiders and were later imprisoned by the ElvenkingThranduil.^[6] They escaped through barrels and they traveled down to Lake-town.^[7]

Thorin and Company were greeted warmly by the people of Lake-Town and hailed the return of the King under the Mountain.^[8]They soon reached the Lonely Mountain and the Dwarves sent Bilbo who converses with Smaug.^[9] Realizing that the Lake-Men must have helped the intruders, an enraged Smaug flew towards Lake-town to take revenge on the Lake-Men. There he was killed by Bard the Bowman who pierced the bare spot on Smaug's left breast.^[10]

Following the death of Smaug, the people of Laketown asked Thorin for a share of the treasure, as they wanted recompense for the destruction of their city, a part of Smaug's treasure originated from their former city, and it was a lord of Lake-Town, who shot the fatal arrow that killed Smaug. Thorin, overwhelmed by greed after recovering his family's riches, and enraged by the presence of Thranduil, refused to share any part of the treasure.^[11] Instead, he sent a raven to seek aid from his relative, Dáin II Ironfoot, who had a legion of Dwarven soldiers on the move to secure the reclaimed mountain city.^[12]Meanwhile, Thorin charged his companions with looking for the Arkenstone within the hoard of treasure. However Bilbo had already found the Arkenstone, and subsequently, secretly brought it to Bard and Thranduil to use as a bargaining counter.^[12]When Thorin learned of Bilbo's actions he became enraged and denounced his former companion as a traitor.^[13]

The Burial of Thorin Oakenshield, by Alan Lee

The growing conflict over the treasure between Dwarves, Wood Elves, and Men, likely to result in bloodshed, was suddenly averted by the approach of Goblin and Warg armies, so they instead joined forces to defeat their common enemies in what was later called the Battle of the Five Armies. During the battle, Thorin led an assault that proved his strength as a leader, striking out from the mountain and providing vital aid as the goblins threatened to overwhelm their foes. He fought courageously, but was mortally wounded in the battle, requiring Beorn to take him to safety.^[13]

Before he died, he made his peace with Bilbo by commending the Hobbit's bravery and good character, apologising for his harsh words as he now recognised his comrade's fundamentally benevolent motives. His last words are, "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. But, sad or merry, I must leave it now. Farewell."^[14][15]