The Thule Intervention occurred in 978.M39, when a conclave of Eldar Farseers from the Iyanden Craftworld appeared without warning in the throne chamber of the High King of Thule. The inscrutable Farseers demanded the entire human population of Thule, be removed within a month or the Eldar would return to remove them by force. After their demands were delivered the Farseers vanished and, rather than face the wrath of the Eldar, the High King soon fled Thule and abandoned his people to their fate. A month later, with the human population still remaining, a large army from Craftworld Iyanden arrived at Thule - only to find a deployment of the Crimson Fists Chapter, arrayed in force against them. During the battle that followed, the Eldar found themselves trapped by the Crimson Fists and suffered heavy losses, before they finally managed to withdraw and escape from Thule.