Ultramarines - Calgarian Rites: In the Era Indomitus, Chapter Master Marneus Calgar was the first or one of the first Firstborn Space Marines to voluntarily undergo the painful and life-threatening surgeries and genetic enhancements required to cross the Rubicon Primaris and ascend to become a Primaris Space Marine. He volunteered for the process to prove to his fellow Ultramarines and fellow Adeptus Astartes that they must embrace their enhanced brethren as a gift of the Emperor rather than fear and resent them. His transformation was overseen by Archmagos Dominus Belisarius Cawl himself, who estimated that there was a 61.6% failure rate at such a transformation until the process was perfected, which would take time and many more such surgeries.The operation to transform Calgar from a traditional Space Marine into a Primaris Marine was conducted in an auto-sterilised medicae vault. Thick with the tang of counterseptic and crowded with elaborate medical servitors, the room was dominated by the great marble slab at its centre, artfully carved with runnels to collect the copious streams of blood that would result from the procedure. The surgery was to be extensive and agonising, a fact Marneus knew well from Cawl's tediously thorough descriptions of the process.A Primaris Marine is gifted three new gene-seed organs in addition to the nineteen originally grafted, sutured and chemically implanted into an aspirant Space Marine. These are the Magnificat, which is buried deep in the brain to stimulate growth and to intensify other organ functions; the Belisarian Furnace, which releases a burst of synthesized hypersteroids and corticostimulants when a mortal blow is dealt so the Primaris Marine may fight on; and the Sinew Coils, cable-like lengths of durasteel that encase every tendon and sinew in a metallic sheath that gives tremendous resilience and strength.During the implantation of the Primaris organs, Marneus Calgar was cut open from crown to heel. His ribcage was cracked apart and -- at the climax of the procedure -- his physiology suppressed to the point that his life slipped away. Choirs of cyber-cherubs sang blissful, overlapping requiems, swaying their aspergillums so that sacred incense might guide Calgar's soul back to his body.The corpse lay in state, its flesh rent and open to the air, for what seemed to those watching like an age. Ten long solar minutes ticked past, then twenty. Skull-faced surgeons clicked and muttered and stabbed at the Chapter Master's tortured flesh. Those around the periphery of the Apothecarion theatre held their breath in dread.Then, with his wounds stitched closed by a thousand jabbing needles and his mighty hearts electrified to beat once more, the newly forged Marneus Calgar was brought back to life. He broke his bonds with a strangulated, blood-flecked roar, stumbling to life as his newly-implanted Belisarian Furnace brought him to instant battle readiness.Calgar had clawed his way back from beyond the brink of death, and in doing so, he had shown his Chapter and all Space Marines that the transformation was possible. The Rubicon Primaris had been crossed, and a new path opened for the Adeptus Astartes. In honour of his courage, the Ultramarines thereafter called the procedure the "Calgarian Rites."