Thror

Thror was the King under the Mountain, the grandfather of Thorin Oakenshield, whose reign ended in ruin when the dragon Smaug destroyed his kingdom and seized the vast treasure of the dwarves. His legacy—the map, the key, and the Arkenstone—drives the entire quest of The Hobbit, and his death in the mines of Moria sets in motion the chain of events that leads to the recovery of the Lonely Mountain.

Identity and Background

Thror was the King under the Mountain, the ruler of the great dwarf kingdom that dwelt in the Lonely Mountain. He was the father of Thrain and the grandfather of Thorin Oakenshield. Under his rule, the dwarves mined and tunnelled, creating huger halls and greater workshops, and they discovered a great deal of gold and many jewels. They grew immensely rich and famous, and Thror was treated with great reverence by the mortal men who lived to the South, who built the merry town of Dale. The toy market of Dale was the wonder of the North. Thror's halls became full of armour and jewels and carvings and cups. The map of the Mountain was made by Thror himself.

The Coming of Smaug and the Fall of the Kingdom

The dragon Smaug, a most specially greedy, strong and wicked worm, flew south one day and settled on the Mountain in a spout of flame. He came down the slopes and set the woods ablaze. The dwarves rushed out of their great gate, but the dragon was waiting for them. None escaped that way. The river rushed up in steam and a fog fell on Dale, and in the fog the dragon destroyed most of the warriors. Then he went back and crept in through the Front Gate and routed out all the halls, and took all the wealth for himself. Thror and his son Thrain escaped with singed beards, but they told Thorin to hold his tongue when he asked how they got away, saying that one day in the proper time he should know. They must have had a private Side-door which only they knew about, and they apparently made a map.

Death and Legacy

Thror was killed in the mines of Moria by Azog the Goblin. Before he went to Moria, he gave the map to his son Thrain for safety. Thrain later gave the map to Gandalf to give to Thorin, along with a key. The map and key became the central objects of the quest, leading Thorin and his company to the secret door in the Lonely Mountain. The treasure of Thror, including the Arkenstone, the Heart of the Mountain, was the ultimate goal of the expedition. The Arkenstone was a great white gem, like a globe with a thousand facets, which the dwarves had found beneath the roots of the Mountain. Thorin valued it above a river of gold. The legacy of Thror's kingdom, its wealth and its ruin, is the foundation upon which the entire adventure of The Hobbit is built.