After the formation of the Codex Astartes, the Fists Exemplar were charged with watching over the Rubicante Flux, a Warp storm that was sporadic in its eruptions and plagued the Abra Sector located on the outskirts of the Segmentum Solar and uncomfortably close to Ancient Terra. To aid the Fists Exemplar with this duty, they were given the Star Fort Alcazar Astra, which had served the Imperial Fists well during the Horus Heresy. With the Fort towed by their ships, the fleet-based Chapter patrolled the Rubicante Flux, for some time until disaster struck. While the Alcazar Astra was being towed to a new location, a sudden massive warp eruption from the Rubicante Flux, blew the Star Fort off course and into the gravitational embrace of a nearby star. Due to the heroic efforts of Chapter Master Dantalion and his Captains, the Alcazar Astra was guided towards the star's nearest planet Eidolica, where it beached itself. Though the Fort was saved from destruction, Dantalion was one of the Fists Exemplar who lost his life in the crash. With the Star Fort forever grounded, the Fists Exemplar adopted Eidolica as their Home World and the Alcazar Astra became their Fortress Monastery.