Good Hobbit Morning chapter 17 "The Clouds Burst"

"Tensions ran high as Dáin's Dwarves sought to reach the Mountain, while archers and spearmen under Bard barred their approach. Conflict began between the Elves and Dwarves, even as a black cloud gathered and the Goblin army under Bolg arrived.

Thus began the Battle of Five Armies, between the Goblins and Wolves, and the Elves, Men, and Dwarves."