Ambitions of Chaos
Warband of Unaligned Chaos Space Marines
Originally a Dark Angels progenitor chapter founded in the 37th Millenium, these space marines were driven from the Imperium due to their grisly chapter rites which eventually turned into dark celebrations of war and death.
Formerly working for the The Undoubtable One, the Dark Consuls fled when they were defeated at the Space Battle of Arbuthnot. At the time they numbered around 500, despite hiding the fact from most of the system.