The Battle of the Behemoth took place when the demon lord Behemoth appeared in the northernmost region of the Eastern Continent. The Behemoth began to slowly march south, to the rest of the continent, with his army of demons behind him. The humans were all in the midst of a war between themselves, The War of the Kings, but they quickly banded together to deal with the Behemoth.
The humans formed a special group known as the Northern Rangers, a large army full of people trained to fight in the snow effectively. The Northern Rangers, along with dragon knights, launched an attack on the Behemoth. Their attacks were unsuccessful, the Behemoth was too strong for them to defeat, so they retreated.
They made a new plan, they would have mages cast a powerful spell while the Northern Rangers and dragon knights distracted the Behemoth and his army of demons. The battle was hard fought, with the humans prevailing. They sealed away the Behemoth and his army beneath a mountain sized slab of ice. The Northern Rangers stuck around the area to keep watch over the Behemoth, to make sure it would never rise again. The humans all realized how effective they were working together, and united under House Vallos to form the kingdom of Valtoria.