Battle of the Five Armies
On September of 2941, Thorin Oakenshield and his company of 11 Dwarves and the Hobbit Bilbo Baggins, arrived at Erebor. After the slaying of the dragon Smaug - who had banished Thorin’s house 170 years ago from the LonelyMountain - by Bard of Dale, they entered it and Thorin became King under the Mountain.
The reputation of the dragon’s hoard attracted the Elves of Mirkwood and the Men of Dale. Thorin called for help from his cousin Dáin who dwelt at the Iron Hills. Soon around Erebor a large number of armies assembled and war was imminent, reminding of the old strife between the Elves and the Dwarves. But an unexpected event caused the hostility to dissolve. A black cloud of bats was seen coming towards the LonelyMountain, announcing the coming of Goblins. They were, too, attracted by the treasure of Smaug, but it was afterwards realized that Sauron, the Necromancer was behind this attack. And there in the mist of confusion Gandalf the Grey appeared and urged them to forget their hatred and fight together against the common enemy.
So, began the Battle of the Five Armies. Upon one side were the Goblins led by Bolg and the Wargs, the Wild Wolves. Upon the other were the Elves led by Thranduil, the Men led by Bard and the Dwarves led by Thorin and Dáin II. The battle was balanced for many hours. Thorin himself came out of the mountain and drove back the assault of the Goblins, but was himself mortally wounded by the bodyguard of Bolg. Then unexpectedly came the Eagles and threw the enemy away from the mountain. But still they were outnumbered. In the last hour Beorn arrived in the shape of a bear and with a furious attack killed Bolg and scattered the Goblins. By nightfall the battle was over and the enemy had fled away to the mountains.
Thus, the lands around Erebor gained peace for some time until the War of the Ring. Dáin II became King under the Mountain and Bard refounded the kingdom of Dale while the hoard of Smaug was distributed fairly among the three people.