The Solar Auxilia was an elite fighting force within the Imperialis Auxilia during the Great Crusade and Horus Heresy originating from the Segmentum Solar.
The Solar Auxillia was founded in the early days of the Great Crusade as the forces of the Emperor required fleet-based armies capable of dealing with “petty wars” and colonial suppression while the Legiones Astartes handled grander campaigns. Imitating the Void Hoplites of the Saturnyne Ordo, the Solar Auxilia were trained, armed, and deployed in the same fashion and were issued with the same Saturnine Void Armour. Their doctrine emphasized discipline, coherence, aggressive defense, and concentrated firepower, making them highly effective soldiers.