Battle of Calth - Orbital Defence: As the southern island cities were being pounded to dust and vapour, the battle in the void was spilling ever further across Calth Near-Space. The world was ringed by over nine hundred orbital defence platforms, each bristling with lance turrets, weaponsbatteries and torpedo launch tubes, but each had been rendered as defenceless and impotent as an unarmed freighter by the usurpation of the defence grid's command systems. Many of these platforms, even the smallest of which were served by crews of hundreds, were engaged and crippled in scornfully opportunistic strikes by passing Word Bearers war ships, while others were simply ignored. A number, however, were singled out for destruction or boarding, again suggesting the existence of some underlying and esoteric pattern to the entire attack. In a phenomenon that would be repeated countless times, the Word Bearers sought out specific enemies to slay in specific ways, as if in doing so they would honour their Primarch, or some other still higher power.Across Calth Near-Space, boarding torpedoes and assault claws exploded from the launch bays of Word Bearers vessels to smash into the armoured flanks of scores of defence platforms. Even as the assault claws fusion-burned through metres-thick armour and torpedoes bored deep into their guts, the platforms' defenders mustered. All available hands were scrambled to oppose the Word Bearers boarding parties, but it was the Solar Auxilia stationed on each platform who would bear the brunt of the fighting. While not as strong or as heavily armed and armoured as the trans-human Legiones Astartes they would be fighting, these defenders were nonetheless the elite of Calth's human forces. Configured according to the long-approved and highly efficacious "Solar" pattern, these units were equipped with vacuum-warded void armour and so could fight even in areas depressurised by the breaching of a platform's outer skin. While not as potent as Legiones Astartes bolters, their weapons were still capable of inflicting significant damage when massed against targets that they could scarcely miss in the platforms' cramped interiors.The greatest advantage the Solar Auxilia defence units had over lesser troops and pressed station hands was their chain of command. Well organised and relentlessly drilled in every facet of "Zone Mortalis" warfare, they could be relied upon to stand resolute against any foe and, if necessary, to die in pursuit of their sacred duty. On a hundred orbital defence stations and more, Word Bearers boarding parties forced their way along passageways swept with torrential blizzards of laser, plasma and flame. The defenders were on home ground and had trained countless times to undertake such duties, and so made the boarders pay dearly for the first few gains they made. The Word Bearers weathered the storm, striding inexorably into the very jaws of death. Ceramite armour cracked and degraded layer by layer as round after round impacted, but few were the truly telling killing blows the defenders could land, and so with lethal inevitability, the Legiones Astartes closed on the defenders' positions. Even then the Solar Auxilia enacted tactical protocols born of generations of void warfare mastered by their Saturnine forebears before the Unification Wars. Lasrifle sections fell back along pre-ordained routes while Veletaris Storm Sections held the attackers at bay with fearsome volleys of volkite fire and searing blasts of flame. Others simply held their position, maintaining a steady rate of fire as death came for them, determined to the last to buy their comrades time to fall back to the next defensible position. But the Word Bearers had gained a foothold and, ultimately, the bold defenders were doomed.As the battle spilled ever deeper into the guts of the defence platforms, the passageways and chambers were transformed into charnel houses. In places, the defenders' resolve was sorely tested when confronted with the unfamiliar combat doctrines certain Word Bearers Legionaries employed. Some chanted mournful plainsong as they advanced, an atonal dirge filling the hearts of all who heard it with dread. Others halted after every kill, pausing to enact grisly mutilation upon the recently fallen. In still more cases, the Word Bearers refrained from slaying cornered or overrun foe, instead handing them off to following mortal units to clap in irons and drag off as prisoners. The fate of these unfortunates can only be guessed at, for the last that was seen of most does not bear recounting.On a scant handful of orbital defence platforms, the Solar Auxilia defenders were successful in repelling Word Bearers assaults, but not without paying a heavy price indeed. On Platform Principia-Veridia 27/ K, a sub-cohort of the 222nd Calth Solar Auxilia rad-purged an entire marshalling deck just as a Word Bearers void-breaching party forced its way on board. The resulting flood of neutron radiation was so intense that even the trans-human physiologies of the attacking Legiones Astartes could not fully protect them. The first of the attackers wavered and the auxiliaries of the 222nd fixed bayonets and charged, their Solar pattern void armour able to fend off the radiation only so long as it took the charge to strike home. Dozens of the stricken Legiones Astartes were overrun before they could react, and seconds later the auxiliaries themselves fell victim to the radiation. Not a single warrior of either side survived, the rad-flooded chamber forming a tomb for enemies locked in a mutual death-struggle for all time.The defence of Platform Elipsia-Veridia 09/Q was equally successful and equally lethal for both sides. In this instance, it is thought that a substantial force of Terminator armour-equipped Word Bearers utilised a rare teleportarium array to board the station and launch a brutal coups de main attack on the station's primary strategium. The station master had scant moments to react and so mounted a noble, if futile, defence of his bridge. The attack had bypassed the large sub-cohort of the 255th Calth Solar Auxilia stationed on Elipsia-Veridia 09/Q , the Word Bearers judging that the defence would collapse with the strategium captured. This did not occur however, for the 255th was commanded by the veteran Lord Marshall Turnus, a beloved leader of advanced years and with countless victories to his name. Determined to strike back at the Traitors even if they could not possibly be repulsed, Turnus ordered the station's Mechanicum magos prime to overload the platform's plasma reactor. The magos refused the Lord Marshall's instruction and so died at Turnus' hand, a bolt round detonating within his platinum-chased skull. His deputy, however, acceded when the Lord Marshall repeated the order, and within minutes the entire platform was consumed in atomic fire, briefly forming a new, deathly star in the tortured skies above Calth.Elsewhere however, even the elite of the Solar Auxilia could not stem the inexorable tide of assault nor blunt the zealous fury of the Legiones Astartes Word Bearers. Valiant troopers died by the thousand, and at last the Word Bearers' intent in boarding specific orbital defence platforms was revealed as the same scene was enacted upon the bridges of scores of defence platforms. Those commanders taken alive were forced to bear witness to the destruction heaped upon the world whose defence they were sworn to. Compelled to watch by the vice-like grip of a Word Bearers Dark Apostle or other senior officer, the last sight these men and women saw served as a vital component in the vast and terrible ritual unfolding on Calth. Much later, it was determined that the intent of this cruelty was to sear the sight of the dying world into each victim's consciousness as an act of witnessing, a scene the Word Bearers believed the dead would take with them to the afterlife as evidence to the powers that hold sway there of the Traitor Legion's deeds.