War of Aesir and Vanir

A war broke out between the Aesir and Vanir, when the Aesir had tortured the Vanir goddess, Gullveig.

Gullveig loved gold. It was all she talked about. Gold, gold, GOLD! The Aesir were tired of hearing her incessant chatter about gold. They bound Gullveig in Odin's hall and pierced her with spears. Three times they burned Gullveig in a magical fire, but each time she was reborn.

The Vanir demanded reparation from the Aesir for torturing their kind – they wanted equal status to their rival – instead of meeting the Vanir's demand, the Aesir waged war against the more peaceful Vanir.

The Vanir, however, were gaining the upper hand in the war. The warlike Aesir were suffering one defeat after another, before they agreed to end hostility and grant the Vanir, equal status.

The peace was followed by strange ritual where the two sides spat in a vessel. The combined saliva in the vessel created a new being – Kvasir was born.

This was followed by a hostage exchange to ensure that peace was kept on both sides. The Vanir Njörd (Njord) and his son Freyr were the Aesir's hostages accompanied by Kvasir, the wisest Van. The Vanir received Hoenir (or Vili) and Mimir (the wisest of the Aesir) as hostages.

At first the Vanir were happy with exchange and thought that Hoenir was as wise as Mimir, until they realised that Hoenir was not very smart at all. Mimir had been secretly giving Hoenir advice. The Vanir felt cheated. They had Mimir decapitated before returning the head to the Aesir. The Aesir did not retaliate in kind. Odin had the head preserved and used it to gain knowledge. (See Head of Mimir and the Mead of Poetry, in the Search for Wisdom page.)

The Vanir, Njörd and his son and daughter, Freyr and Freyja, were greatly honoured by the Aesir, by giving them places among them as Aesir. However, the mother of Freyr and Freyja was Njörd's own sister (who was unnamed). Incest and marriage between siblings were allowed in Vanheim, but not so in Asgard. So when Njörd went to Asgard with his children, he had to give up his sister-wife.

Njörd would return home to Vanaheim when the Aesir gods fought the frost-giants at Ragnarok, according to the short passage in Vafthrudnismal (Lay of Vafthrudnir).