Calderis is a Feudal World in the Sub-sector Aurelia of the Korianis Sector known for its arid climate and hardy warriors. The Blood Ravens Space Marines Chapter have recruited from this world for millennia. An Imperial Planetary Governor oversees the planet from a space station in orbit. Calderis is one of the three planets that served as the setting for the PC game Dawn of War II.
Following the Exterminatus action on Cyrene, the Blood Ravens were in need of a new world to glean recruits from. Calderis would prove to be the solution. The planet was a great source of hardy warriors, many eager to fight in service to the Emperor. The existence of temples and weapons manufacturers on the planet made it appear all the more obvious that Calderis was suited to be the successor for the old recruiting world. Following the devastating losses sustained during the Kaurava Campaign, this very world's continued existence (as well the rest of the sector's wellbeing) would be the only chance that the Blood Ravens might sustain themselves.
During the events of the First Aurelian Crusade, Calderis was ravaged by a plethora of problems. First came an Ork WAAAGH! led by a Goffs Ork Warboss named Gutrencha. As this world was crucial to the Blood Ravens, the Orks couldn't be allowed to live. No sooner had the Orks been cleared off that a new, more potent threat arrived- a Tyranid invasion that may have been averted by Aeldari planning had the Blood Ravens ceased interfering. The casualties were considerable and, during the assault, Captain Davian Thule suffered a considerably potent (and poisonous) attack from a Tyranid Warrior. Despite the pain that the Blood Ravens suffered, they were able to save Captain Thule and beat the beasts back. Eventually, the Blood Ravens returned not only to expunge the Tyranid infestation, but also rub out the real Warboss of the WAAAGH! that plagued the planet.
Alas, this would prove to be only the beginning of the troubles. Some time later, during the Second Aurelian Crusade, all but Captain Apollo Diomedes, the only surviving Blood Raven present on the planet, would fall prey to the tricks and daemons of Chaos. Thankfully, some heroes were able to kill the source of the Chaos corruption that was on the planet -- Apothecary Galan -- but would learn of a far greater source of Chaos infestation. Though it took some convincing on Sergeant Tarkus' part, Captain Diomedes eventually realised that there was indeed Chaos corruption in the Blood Ravens and allowed the heroes to leave.
The final -- and most fatal -- of all the problems occurred during the Third Aurelian Crusade. Azariah Kyras, the fallen Chapter Master and Chief Librarian of the Blood Ravens, wished to be hidden from the prying eyes of the Imperium; as such, he convinced Sergeant Lysandros to raze Calderis' Argus Settlement (and any other inhabited areas) to the ground, Blood Ravens bases included. No soul would live to tell the tale, leaving Calderis little more then a barren dustball coated with ruins.
Thankfully, Captain Diomedes, working alongside other Loyalist Blood Ravens, prevented the total destruction of Argus Settlement's most important civil locations, though some destruction to the area was inevitable.