The Aesir-Vanir War was a war fought between the Aesir tribe and the Vanir tribe of Norse Gods that led to the unification of the two tribes as a single pantheon.
History[]
The Aesir-Vanir war started after Gullvieg, the Vanir goddess of magic, went to the Aesir under the alias Heior, and offered them an easier way of life by using magic. However they soon realized that their traditional values of kin loyalty, obedience, and honor were being pushed aside in favor of their own desires they sought through the stranger‘s ways. When they realized this the Aesir burned her alive three times, as she would be reborn from her own ashes whenever she died.
Due to the burnings of Gullvieg, the Vanir declired war on the Aesir and the two tribes fought one another. While the Aesir fought with tradition weapons, the Vanir fought by using magic.
Eventually a truce was made. As an agreement, the gods all spit in a barrel and created Kvasir, the god of wisdom. Also, each of the tribes send a member to the other in the peace treaty: Frey, Freya and Njord went to Asgard while Mimir and Honir went to Vanaheim.
Magnus Chase and the Gods of Asgard[]
The Sword of Summer[]
Mimir mentions the war to Magnus Chase, Samirah al-Abbas, Blitzen, and Hearthstone when the severed head first meets the son of Frey.