The Clouds Burst
The Clouds Burst is the 17th chapter of The Hobbit.
Thranduil, Bard, and Gandalf plead with Thorin to share the wealth of Erebor with the people of Middle-earth. They reveal themselves to be in possession of the Arkenstone, which was previously stolen by Bilbo. Thorin reluctantly agrees to part with 1/14th of his treasure in trade for the Arkenstone, although he rages against Bilbo and casts him from Erebor in anger, their friendship apparently broken. In preparation for the upcoming battle, the sturdy, mattock-wielding Dwarves of Dáin Ironfoot have come as reinforcements. Tensions run high as Dáin's Dwarves seek to reach the Mountain, while archers and spearmen under Bard bar their passage. Battle begins between the Elves and Dwarves, even as a black cloud gathers and the Goblin army under Bolg arrives.
Thus begins the Battle of Five Armies, between the Goblins and Wild Wolves, and the Elves, Men, and Dwarves. We learn that the Goblins have been amassing in the wake of the Great Goblin's death, and have set themselves on capturing the Lonely Mountain. A strategy arises: the goblins will be lured into the valley between the arms of the Mountain, and there cornered and destroyed. Bilbo wears the ring to harness its invisibility. The Elves charge first, and kill countless Orcs in fury. Then the dwarves under Dáin attack, routing the enemy and striking panic into the orcs. Victory seems to be at hand, when the forces of good are ambushed by Orcs, scaling the Mountain.
Battle rages on, with Bard defending the Eastern spur of the mountain, and the Elves fighting on Ravenhill. Thorin and the Company burst out of the mountain in battle armor, rallying morale. Calling all elves and men to him, Thorin rallies the dwarves and men on a counter-attack against the orcs. Thorin attempts to break the bodyguard of Bolg, composed of goblins of huge size. But no progress is reached, and the tide of battle begins to change. The armies of men, elves and dwarves find that their efforts are in vain, as the countless numbers of orcs and ceaseless onslaught renders their efforts futile.
Bilbo, fighting on Ravenhill with the elves, cries in disdain as defeat is near at hand. He regrets the death and ruin caused by the golden hoard of Smaug. Then out of the sky, the majestic Eagles swoop down in great numbers, prompting Bilbo to cry "The Eagles! the Eagles!" in joy. Bilbo is then struck by a hurtled stone, and rendered unconscious.