The Erellian Subjugation occurred in 008.M31 during the Horus Heresy, when a battlegroup of the Iron Hands and Salamanders Legions, attacked the Traitor-held world Erellia.
Elements of the Emperor's Children and Iron Warriors were rearming on Erellia, when the Loyalists attacked. The Traitor Legions were caught by surprise and their forces were eradicated on the world's mustering grounds by the battlegroup. In the aftermath of their deaths however, the Iron Hands began a brutal subjugation of Erellia's population. The Legion saw its population as willing supporters of Warmaster Horus' cause, but as the massacre began, the Salamanders attempted to stop them. The last Astropathic message, hurled in desperation, from Erellia spoke of the Salamanders' intervention causing violence to erupt between them and the Iron Hands.
- 1: White Dwarf 470, pg. 102 - Chronicles of the Horus Heresy