Battle of Calth - Opening Gambit: The captured tender Campanile had crossed the inner defence ring of Calth, its codes accepted as authentic by the orbital defence grid. The mass of the Ultramarines' fleet lay in its path as well as Calth's massive orbital dock yard complex. As it passed within the orbit of Calth’s moon, it began an abrupt acceleration. The captured vessel screamed into Calth’s orbit like a streaking projectile fired from a bolter, heading directly for the Calth Fleet Yards and the fledgling infrastructure of the planet's first proper superorbital ring. It somehow managed to miss some of the larger vessels, grazing them with its Void Shields and skimming the surface of others. Smaller craft that lay in the Campanile 's path were utterly annihilated; cargo boats, lighters, ferries, maintenance riggers. The Ultramar Azimuth Graving Dock was vaporised by the runaway vessel. Several Ultramarines vessels suffered catastrophic hull damage and multiple orbital manufactory modules were destroyed, instantly killing thousands of Imperial Artificers and engineers. The Campanile lost none of its momentum and continued with its suicidal orbital plunge.Still moving, the captured vessel punched through a hollow construction spheroid that housed three separate vessels, obliterating them all. The assembly ruptured and the debris was propelled into the attached habitat modules, voiding them into space. The devastating trajectory of the Campanile caused the Calth Veridian Anchor to shudder under the onslaught. Internal explosions occurred throughout the structure as even more starships in various states of disrepair were destroyed or catastrophically damaged. Larger Battleships exploded as their power plants and vast ammunition stockpiles were critically compromised. Huge, burning sections of the orbital yards' superstructure as well as the debris of destroyed vessels rained down upon the surface of Calth. The Ultramar Zenith Graving Dock suffered integral gravimetric failure and dropping out of orbit, twisting and breaking as it plummeted to the planet below. The massive Grand Cruiser Antrodamicus, supported by the dock, ripped free of its moorings and slid backwards, caught in the gravity of Calth. With its drives off-line it had no power to stabilise itself or prevent its inevitable doom.The Campanile continued to plow through the orbital installations surrounding Calth, shooting forward like a solid projectile, a gargantuan mass of streaking death. It annihilated a pair of slipways and the ships within them, ramming through the vital data-engine hub and destroying multiple data-engines as well. As the automatics failed and the noosphere experienced a critical and fatal interrupt, the orbital fleet yard’s power core was obliterated, killing over 35,000 men and women. The Campanile finally broke up, still travelling at immensely high realspace velocities, and a large chunk of the disintegrating vessel spun out of control and destroyed another Ultramarines Battleship. The remaining pieces of the Campanile cleared the far side of the Calth Veridian Anchor and rained down, burning like meteorites, upon the surface of the planet.Aboard the Samothrace, Sorot Tchure and his Astartes killed most of the ship's crew. Advancing to the main bridge, burning through blast hatches that had been closed in desperation, Tchure confronted the ship's captain, who solemnly announced his disinclination to assist the traitorous Word Bearer. Ignoring the officer, Tchure brutally killed him, letting the body drop to the deck. The Word Bearers then proceeded to coldly murder the entire bridge crew. The Battle of Calth had begun in earnest, as the Word Bearers and their Chaos Cultists began forming up in their thousands for the brutal assault upon the surface.