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By Your Command – Gav Thorpe

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A Black Library Publication

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BY YOUR COMMAND

Gav Thorpe

+resetsoullogistics+imprintcorticalvalueset+setuserdefinitiontoundra+rebootfromstart+

{Awaken this dormant spirit of destruction.}

+calibrateaggressionmetrics+inloadtargetingdata+revisetargetingdata+rebootfromstart+

{Give life unto this shell.}

+inloadrunicadjustment//:parameter4+restartlodestoneprotocols+inceptdatasmithlogin+

{Look upon your servants and grant them the boon of your warrior.}

+activate+acknowledge+alpha-6-terror+

{Destroy the unfaithful. Secure the Casus Belli. Protect the faithful.}

+Respond, Alpha unit.+

Cogitators buzzed into a semblance of life, accepting the designation as the first of its maniple to be awoken.

[Alpha 6-Terror online]

Dim light seeped through the visual sensory circuits of the kastelan, blurring into recognisable shapes. A ceiling, crossed by parallel coolant pipes that dripped condensation. Metal walls inscribed with the twelve-toothed cog of the Cult Metalica. The figure of Datasmith Undra, garbed in hooded white robes, censer hanging from a chain in one mechanical hand and the rod of initiation clasped in an articulated claw. Focusing on the face within the hood, Alpha 6-Terror skimmed through a selection of spectrum filters until the bionic visage of the datasmith came into view. Multifaceted eyes regarded the kastelan from within a cluster of shifting ceramic scales, which slid into an approximation of a satisfied smile.

'Bless the Omnissiah,' declared the tech-priest.

Five other kastelans waited dormant behind Undra, their broad, tall frames dwarfing the tech-priest. Each was a duplicate - rounded plates and barrel chests painted white, marked with the symbols of the maniple. Arming servitors attached gun-limbs and shoulder-mounted heavy weaponry to the forms yet to be awoken. Alpha 6-Terror felt the input links of its own limbs and raised two massive hands. A cortical impulse activated the power field within, enclosing the fists with a sheen of blue energy. Another artificial nerve-twitch brought the shoulder-mount phosphor blaster online. A sense analogous to satisfaction permeated the kastelan's programme as the first large calibre round clanked into the breach.

[Weapons active. Mission parameters detected. Destroy. Secure. Protect.]

Alpha 6-Terror waited for Datasmith Undra to perform the rituals of awakening on the other battle robots. Sensory banks continued to analyse the robot's surroundings, creating an impression of the shrine-chamber and the environment further afield. As they synchronised with the archive storage of the kastelan, auditory inputs filtered with the regular noises - the hiss of the servitors' pneumatics, the vibration of the Imperator Titan's power system, the dump of Datasmith Undra's tread across the plascrete deck.

An echo of sharp retorts and a growl of chain weapons slipped through the kastelans processors. They were accompanied by vocalisations of humans - and human-analogues - in anger and distress.

[Battle is ongoing.]

'Yes, Alpha 6-Terror, the Casus Belli is under attack.'

The kastelan listened for five more seconds, analysing the sounds of conflict with the aid of its auditory archives. Fresh datastreams cut through its programming, seeking to fill in the gaps left by the mission inload.

[Auditory pickups detect boltgun fire. Boltguns are not standard issue for the skitarii or auxilia of the Casus Belli. Boltguns are standard issue armaments of the Space Marines of the Adeptus Astartes. Adeptus Astartes are not part of the standard crew complement of the Casus Belli.]

'Yes, Alpha 6-Terror, we are being assaulted by Heretic Astartes. Check your deployment datalog for context.'

The kastelan accessed the information that had been installed as part of the awakening ceremony. Within, it discovered that the Imperator Titan Casus Belli, to whose defence the maniple was currently assigned, had been deployed with a supporting battle group to the planet Nicomedua. The Nicomeduans had rebelled against the wisdom of the Omnissiah, including a large proportion of their tech-priests and other members of the Cult Mechanicus that served them. The Imperator was currently embattled whilst eliminating a fortress-city known as Az Khalak. By gunship, renegade Space Marines allied to the hereteks had boarded the akropoliz - the massive superstructure atop the Titan's shoulders that housed garrison chambers and a great part of the Imperator's arsenal.

Among the din of battle, Alpha 6-Terror picked up wildly oscillating sounds that scaled up and down the audio spectrum, passing above and below even the kastelan's detectable range.

[Systems detect unknown sonic weapons. Capabilities unknown.]

'There are several types, highly customised. Multi-functional. Penetrative effects for certain wavelength projections have been estimated to a value equivalent to autocannon armour-piercing shells. Be wary of them.'

Alpha 6-Terror appended a warning sub-routine to the sound file it had created.

[Specify wavelengths.]

The datasmith squawked a pulse of binaric that inloaded to the kastelan's artificial consciousness. Delving into the contents of the data-packet, the robot decoded the high-pitched sonic attack that had been identified as the most damaging to armoured targets. It overlaid the data onto its warning systems so that it would know when one of the anti-armour pulses was being fired nearby.

The kastelan reviewed its motor and cogitation systems while Datasmith Undra finished activating the other robots. Every system seemed in good repair and responding within expected parameters.

[Mission and combat context fully established. Battle readiness now at one hundred per cent.]

'Wait for the rest of the maniple, Alpha 6-Terror.'

[Battle readiness is at one hundred per cent. The enemy are slaying servants of the Omnissiah. Castigation of the foe is delayed.]

'And you will be destroyed if you try to face them alone. They are Space Marines, Alpha 6-Terror. Set your peril quotients to their highest value.'

The kastelan did as commanded. It remained silent as the other warriors of the maniple regained consciousness and vocalised their readiness for battle. When all six were awake, Datasmith Undra had them assemble in a line facing the broad door of their storage chamber next to the cybernetika shrine.

'Check authorisations,' he told them.

Alpha 6-Terror ran its command protocols to verify the datasmith's authority. The maniple replied near simultaneously.

[Datasmith Undra is in command.]

'Confirm mission fundamentals.'

[Destroy. Secure. Protect.]

Alpha 6-Terror's strategic programming was rudimentary, conveying enough knowledge of the local battlesphere and participants to avoid a major detrimental incident but nothing more. The kastelan knew from residual noospheric awareness that the maniple had been deployed to intercept a squad of Heretic Astartes that was moving to reinforce the main attack against the Imperator's akropoliz atrium where ingress to the command and engineering decks was possible. Telemetric data informed the robot that the maniple advanced along two parallel lines - two kastelans through the starboard armoury corridor and the remaining four via the broader transit gallery that ran alongside.

From just behind the robots, noospheric pulses from Datasmith Undra kept them advancing like the digital goads of a swineherd, nudging a kastelan forward if a pulse of incoming data distracted or delayed it. From the datasmith's fleeting contacts Alpha 6-Terror gathered that the intent was to contact the enemy squad from two directions simultaneously. Alpha 6-Terror and the three other kastelans in the main group would engage initially and the remaining two robots would attack from behind the embattled enemy from their flanking position.

The soundsphere was intense, the corridor walls reverberating with the noise of bolt detonations and crack of arc rifles. Danger assessment routines idled at the lack of sonic weaponry close by - bolters were primarily an anti-personnel armament and posed little threat to the battlehide of a kastelan. Proximity calculations from the light flickering against the mural-covered wall ahead indicated the fighting was just a few metres away, around the next junction. A skitarii clad in a white coat staggered backwards into view. Blood spray from a wound in the soldier's arm signified arterial damage.

Another bolt struck the skitarii, exploding within the chest cavity. The injury was instantly fatal, almost cutting the soldier in half with its violence. Alpha 6-Terror's aggression value grew as it monitored the corpse flopping bloodily to the floor. The kastelan quickened the pace of its strides, power to the legs amplified by the activation of a retaliation programme.

The noosphere hummed with the datasmith's increased presence.

Undra [maniple broadcast / imperative] : >Maintain coherency. Attack as a single unit.<

Alpha 6-Terror slowed, reined in by the datasmith's intervention. Heat sensors detected four sources close at hand, all of them too high to be human forms.

Zeta 6-Terror: >Powered armour signatures detected.< [theory] >All non-Heretic Astartes combatants non-functional.<

Alpha 6-Terror [affirmative]

Undra [affirmative / imperative]: >Battlesphere is clear of faithful personnel. Engage slaughter mode. The Machine-God demands restitution. Leave no survivors.<

Maniple Relay: >Destroy. Secure. Protect.<

An explosion of white paint flecks and metal splinters engulfed Alpha 6-Terror a second before its systems parsed the visual and auditory inputs of enemy pounding into view, the muzzles of their bolters alight.

+impactsdetected+initialisedamageassessment+surfacedamagedetected+appraisal=negligible+

The Space Marines moved too fast to accurately track, forcing Alpha 6-Terror to rely on trajectory-prognostication equations to direct the fire of its phosphor blaster. Flaming shells joined its fusillade from the kastelans to either side, filling the junction with burning projectiles. The targets were gone even as phosphor immolated across the far wall, setting the corridor ablaze from floor to ceiling.

Reviewing the last split-second engagement, Alpha 6-Terror archived a vision of a tall, broad figure clad in garishly painted power armour. The helm was crested with a line of glinting spikes, a cloak of brightly patterned hide from an unidentified xenos species flowing around the backpack. The second combatant was likewise adorned with ostentatious battleplate, his helmet sculpted into a screaming, monstrous face.

A flutter of electronic signals excited Alpha 6-Terror's neural analogues. [Enemy detected! Destroy! Secure! Protect!]

The other kastelans echoed the call, mechanised voices resounding with their thunderous footfalls and the crackle of flames. The maniple pushed on, splitting their fire arcs to either side.

Alpha-Epsilon 6-Terror: >Right flank monitored.<

Beta-Zeta 6-Terror: >Left flank monitored.<

Undra: >The enemy are trapped. Expedite their terminations.<

Schematic analysis showed that there was no route past the kastelans, or their companions in the adjoining passageway. Alpha 6-Terror broke into a lumbering run, reaching the junction a few strides ahead of the rest of the maniple. A hail of bolter fire met the kastelan, cracking against its battlehide.

+impactsdetected+initialisedamageassessment+surfacedamagedetected+appraisal=negligible+initiatecounterfire+

The phosphor blaster barked rounds into the closest renegade to the left as Alpha 6-Terror lumbered around the corridor junction. Flaming bullets shattered the Space Marine's ablative pauldron, scattering chunks of charred ceramite. The weight of fire forced him back, shell after shell slamming into the exposed armour layer beneath.

Another threw himself forward, wielding a red-edged power sword. The blade bit into Alpha 6-Terror's arm raised to ward away the blow, its crackling energy wave slicing down to the sub-systems within the structure of the limb.

+impactsdetected+initialisedamageassessment+internalrightarmdamagedetected+appraisal=non-critical+redundancysystemactivated+

Alpha 6-Terror punched with its other hand but the Space Marine was already ducking beneath the blow. The fist slammed into the wall with a burst of crackling power, leaving a crater in the plastered ferrocrete.

+impactsdetected+initialisedamageassessment+internalleftlegdamagedetected+appraisal=acute/temporary+

The kastelan stepped back to give itself more room to attack once more, bringing a bulky forearm down onto the backpack of the Space Marine as he tried to dodge again, dragging his blade free of the gash it had cut into the robot's thigh armour. Even the superhuman body and reinforced battleplate was insufficient guard against the raw strength of the kastelan. The backpack sheared away from the rest of the armour, staggering Space Marine against the wall. Alpha 6-Terror's other fist drove directly into the faceplate of the renegade, driving the crested helm into the wall. Ceramite cracked. As did the bone within.

The snarl of powerfists and roar of phosphor-blasters engulfed the junction as the other kastelans charged past.

+threatlevelsignificant +targetsurvivaldataunknown+ensuretermination+

Alpha 6-Terror buried its fingers into the remnants of the Space Marine's skull and dragged the bloody mess across the wall. With its other hand gripping the plastron of the war-plate, the kastelan ripped free the remains, bringing a portion of severed spine away with the head.

+enemylifesignszero+

Releasing its grip, Alpha 6-Terror turned. Target identifiers danced across the swirl of bulky figures on the opposite side of the junction.

Undra [alert] [alert] [alert]

The signal sent a thrum of urgent cogitations crackling through Alpha 6-Terror, shunting aside secondary datastreams to focus the kastelans attention. For a split second the robot hesitated, unsure what to do.

The emergency transmission from the datasmith started to fade. With empathic threat signals ripping like panic through its systems, Alpha 6-Terror scoured the corridor with every sensor, seeking the tech-priest. It located a body slumped against the wall behind Beta 6-Terror, the marks of a chainblade raked across sternum and abdomen. Glittering scales spotted with red littered the deck around the tech-priest.

A sense of damning mission failure trembled the kastelans processes until it detected a faint flicker of life signs.

Undra [alert] [alert] [threat] [terminal]

Through the press of armoured combatants the kastelans visual systems detected one of the two surviving Heretic Astartes raising a bolt pistol. The weapon was not directed at the robot bearing down upon the squad leader but aimed at the wounded datasmith.

+commanderterminalevent+extremeintervention+

Alpha 6-Terror shouldered aside Zeta 6-Terror and hurled itself towards Datasmith Undra. It crashed heavily into the wall beside the afflicted tech-priest, a flare of warnings coursing through its system from the impact.

Alpha 6-Terror called out to the rest of the maniple as it lunged.

>Destroy!<

Bolts sparked against the battlehide of its back, monitoring systems following their progress from the lower lumbar region to the left shoulder. Converging phosphor rounds from the rest of the maniple seemed to pick up the Space Marine and hurl him down the corridor, trailing fire like a meteor. The fusillade was continued by Delta 6-Terror and Gamma 6-Terror arriving from the opposite direction. Their fist-mounted blasters glowed hot with discharge as they continued to pound shells into the broken remains of the Space Marine, advancing steadily as they did so.

Undra [alert / terminal / threat / sanctuary]

Alpha 6-Terror manoeuvred its form to shield the datasmith from further harm while Zeta 6-Terror tore apart the last heretic with its powerfists.

Undra [alert]: >Preservation inload.<

The gunfire had ceased, allowing Alpha 6-Terror to straighten. Pieces of bolter shrapnel and broken battlehide cascaded from its back. Metallic fingers scratched at the kastelan's leg and it focused its visual surveyors on the datasmith. The tech-priests life signs were almost below detection and falling swiftly.

[Pulse rate below optimal survival levels. Brain activity diminished. Blood loss irrevocable.]

It noticed that the lower part of the face had been destroyed by the blow that had rent open Datasmith Undra's torso. The tech-priest could not speak, each attempt ending only in a froth of blood from the savaged mandible.

Undra [alert / imperative / emphasis]: >Preservation inload.<

Beta 6-Terror: >Datasmith is experiencing near-terminal event.<

Zeta 6-Terror [correction]: >Datasmith is experiencing terminal event not yet concluded.<

Beta 6-Terror [affirmative]

Delta 6-Terror: >Mission parameter remains. Destroy. Secure. Protect.<

The kastelans turned away, but the clink of metal on metal drew Alpha 6-Terror back to the dying tech-priest. Blood and gelatinous lubricant spilt from the grievous wound as Datasmith Undra heaved himself after the robot.

Undra [alert / imperative]: >Preservation inload.< [Emphasis] >Protect.<

Cogitators whirred as Alpha 6-Terror assimilated the change in data. Understanding trickled across its circuits and it deactivated a powerfist, extending the hand down towards the datasmith. A dataport clicked open between the chunky fingers. A mechadendrite tipped with a data-spike slithered from underneath Datasmith Undra's robes, worming its way up the outstretched arm to Alpha 6-Terror's hand. The robot stooped, bringing the dataport closer.

With a wheeze, the tech-priest summoned enough strength for a final effort. The dataspike rose like a serpent about to strike and then darted towards the kastelans fist, fitting into the dataport with a soft click.

+initiatepreservationinload+undraidentitymatrixinloaded+undrapolyformatinloaded+undrasecdonarydatainload+undraarchivestorageinload+

The digital essence of the tech-priest flowed like electricity through cables, flooding every part of the robot's artificial nervous system. Data-streams slipped alongside engagement protocols and defensive posture equations, nestling roots into logic circuits like fast-growing vines. So great was the accumulation of data that had been Undra that it required all of Alpha Terror's primary system space simply to store it. Temporary programmes cycled into dormancy to divert processor power so that some animus could return to the spirit of Datasmith Undra.

{I persevere!}

[Integrated noospheric communication. Query?]

{My soul is within your body, Alpha 6-Terror. You have no noospheric broadcast system so I must communicate via your internal systems.}

[Knowledge input accepted! Continuing with primary battle objectives. Destroy. Secure. Protect.]

{No! You must protect me, even in post-material form.}

[Protect. Yes. Datasmith Undra is protected within my systems and battlehide.]

{You need to return to the Orphic banks of the metempsykoza so that my animus can be made safe while a new material form is created.}

[Protect.]

{The Space Marines are between us and the metempsykoza. I need you to lead the maniple back to the shrine chamber.}

[Command input accepted.]

Alpha 6-Terror started after its companions who had moved back into the main arterial corridor seeking fresh foes. The kastelan detected the pulse of recalibrating sensors, sweeping the vicinity for life signs, gunfire and other indicators of hostile presence.

Alpha 6-Terror [imperative]: >Protect. Datasmith Undra has inloaded his animus to my systems. The maniple must return to the shrine chamber.]

Beta-Gamma-Delta-Epsilon-Zeta 6-Terror [negative]

Alpha 6-Terror [imperative]: >Datasmith Undra commands that we return to the shrine chambers.<

Beta-Gamma-Delta-Epsilon 6-Terror [nominate]: >Zeta 6-Terror focal.<

Zeta 6-Terror: >Noospheric authorisation required. Current command parameters are to destroy, secure and protect.<

Alpha 6-Terror: >Noospheric authorisation impossible.< [emphasis] >We must protect Datasmith Undra.<

Zeta 6-Terror [negative]: >Primary mission is to destroy. Secondary mission is to secure. Tertiary mission is to protect. Active enemies detected in the vicinity. Destruction protocols must be followed.<

The other kastelans turned away and stomped down the corridor, heading in the direction of the sound of gunfire. Alpha 6-Terror watched them go, lacking the means to change their dominant command.

[Maniple re-task attempt failed.]

{You did what you could, Alpha 6-Terror. There appears to be no immediate threat in the area. We should wait here for reinforcement.}

[Negative. Last strategic update demonstrates enemy making progress towards the shrine chamber. If it falls, the metempsykoza ports will be denied. Protection requires that the shrine chamber is secured. Securing the shrine chamber requires potential occupying foes to be destroyed. Protocols restored. Protect. Secure. Destroy.]

Having resolved the programme conflict, Alpha 6-Terror identified the shortest route back to the shrine chamber. It took them directly across the floor of the atrium, past some of the thickest fighting.

{You must avoid all potential threats! Destruction of you is the death of me. Avoid conflict when and where possible, Alpha 6-Terror.}

[Combat parameter input accepted.]

+aggressionvaluezeroed+tacticalawareness=cautionary+reevaluateobjectiveroute+

Charting a more circumspect course across the akropoliz, Alpha 6-Terror plotted a path underneath the main battery and down a secondary access corridor.

[Impossible to predict all enemy movements. Probability of enemy encounters rated as high, Datasmith Undra.]

{Then let us pray to the Omnissiah to guide our steps and your weapons.}

+initiatefaithmode+machinegodconnect+uploadpetition+

Incoming threat warnings almost overloaded Alpha 6-Terror's tactical protocols. Raking volleys of fire from two Space Marines holding a chamber ahead combined with the thrum of an autocannon pounding shells into the kastelan's flank from a gallery across the broad hall.

It was an empty skitarii drill chamber, large enough for thirty soldiers to practise their close-quarters techniques. The broad floor was broken by mock buildings and low obstacles, the walls lined with empty weapons racks and open lockers. The schematic of the akropoliz informed Alpha 6-Terror that the door ahead where the Heretic Astartes held out led to an annex just above the shrine chamber. A functioning conveyor within the antechamber could take them down to the lower deck. They were almost at the objective.

+damageassessment+appraisal=armourcriticallydegraded+

{You must seek cover, Alpha 6-Terror.}

The robot's self-preservation routines were sparse, and entirely unsuited to the role of protecting the digital spirit now housed within its artificial body. It loosed a short burst of fire from the phosphor blaster, forcing the renegades back through the door by which they had entered. At the same time, the kastelan turned and strode beneath the roof of a plascrete house, sheltered briefly from the ire of the heavy gunner. A fresh fusillade rocked the flimsy roof, several projectiles punching holes in the mock tiles to slam into the metal-sheeted floor.

+ammunitionwarning+phosphorblasterammunitionlevelsdepleted+requestreload+

There were no supply servitors to hand. No tech-priests either. The few faithful combatants they had encountered had either died shortly after, or been moving to other parts of the akropoliz.

The nearness of the mission objective set off a cascade of routines that heightened the kastelan's aggression values. Abandoning any notion of a defensive posture, the robot burst through the wall of the fake dwelling, firing the last score of rounds from the phosphor blaster at the Space Marine on the gallery above. The welter of fire cracked open his breastplate, toppling him backwards into the wall as Alpha 6-Terror broke into a lumbering run.

Rather than be trapped in the smaller antechamber, the last two renegades broke into the drill hall, the fire of their bolters hammering at the broken leg armour of the kastelan in an attempt to bring down the mechanical behemoth. Splitting to either side, they used their speed to circle around the charging automaton, keeping well out of range of its devastating fists.

{Secure! Protect!}

Datasmith Undra's urging intercepted Alpha 6-Terror's assault programme just as the kastelan was about to veer towards one of the Space Marines. Reminded of its principle duty, the robot ploughed on, ignoring the bolts striking sparks from its back as it plunged through the door.

+damageassessment+appraisal=functionaldorsalloss=systemfailureimminent+

The fresh peril warnings brought the kastelan to a halt just inside the antechamber, turning thicker armour towards the precise bursts of fire that chased it through the door. Cracks lengthened across the armourplas of its surveyor dome, threatening to shatter the cover and expose the sensor devices within.

It raised its hands, improvising a shield with the energy field that crackled around its powerfists. More bolt detonations engulfed the doorway with yellow flames and showers of razor-edged metal.

The firing ceased.

Alpha 6-Terror left its hands covering its sensor dome, expecting the fusillade to recommence. A routine energy spike through the robot's auditory sensor units detected, the thud of metal on the stone behind. Unable to turn its visual sensors for a positive identification, Alpha 6-Terror tried to deduce the nature of the newcomer with heat and sound probes. The datasmith gave voice to the returning signals, sharing the same cortex pathways that transmitted them to the kastelan's neural centre.

{Large, heat source, radioactive cell. Power surge!}

[Space Marine]

Alpha 6-Terror stumbled and turned, ungainly in its haste to face the new threat. A blaze of shells streamed past, out through the door. Simultaneously, the kastelan registered the impact of solid shot on Heretic Astartes power armour and the towering form that occupied most of the antechamber. It stood high on four jointed legs, several combat blades gleaming on limbs from its underside while a twin-barrelled serpentine and rotary heavy stubber flanked an insectoid head.

A pulse of noospheric power shook the kastelan, far stronger than anything from Datasmith Undra. Instantly authority-recognition circuits quivered under the identifier pulse of Magos Domintis Exasas, overall commander of the defence force of the Casus Belli.

Phosphor shells from the serpentine joined the next heavy stubber fusillade, and among their roar the Magos Dominus reached out a noospheric contact.

Exasas: >Enemy forces are converging on the akropoliz atrium. All defence elements are required to resist the attack.< [inquiry] >Why are you not with your maniple, Alpha 6-Terror?<

Alpha 6-Terror: >I am conveying the spirit of Datasmith Undra to the metempsykoza following emergency preservation inloading.<

Exasas [affirmative]

The huge battle-form advanced, revealing a squad of skitarii behind coming out of the conveyor. The Magos Dominus strode into the drill hall without further comment, the skitarii following swiftly. Alpha 6-Terror watched them dash across the hall and exit at the far end, their commander following a few seconds later.

The departure of the Magos Dominus left an absence in the noospheric conductors of the kastelan, approximating sadness.

[I am needed elsewhere. Destroy. Secure. Protect.]

{You are built to last beyond one battle, Alpha 6-Terror. Your task is to sustain me for future service to the Machine-God.}

The kastelan considered this.

[What is the consequences of failure?]

{I do not understand the question. Alpha 6-Terror.}

[If I should fail to reach the metempsykoza, what will be the consequences?]

{My machine-spirit will not be replaced in a new form and I will die.}

[What does it mean to die?]

{Death. To be dead. The cessation of physical activity.}

[You have already ceased physical activity. Are you dead?]

{The cessation of physical activity and conscious thought.}

Alpha 6-Terror turned away from the door, lining up to enter the conveyor on the other side of the small chamber. Even as its visual sensors focused on the open cage, impaired by the cracked dome and a visible static of other damaged systems, crackling audio senses detected an unfamiliar noise. It was a low drone that started to rise in pitch and volume.

Rotating its upper half back towards the doorway, Alpha 6-Terror spied one of the Heretic Astartes on the balcony where earlier the autocannon-armed renegade had stood. The warrior's armour was even more outlandish than that of his deceased companions, sporting extravagant fluted vanes from its backpack, a spiralling horn adorning the forehead of his helm.

The weapon the warrior carried matched nothing in Alpha 6-Terror's databanks, being somewhat like a lascannon held in an underslung position, but with far more cables, grilles and a grotesque leering faze for a muzzle. The air around the Space Marine throbbed with bass notes beneath detection range, sending pulses of plaster dust dancing in complex sworls across the renegades garish war-plate.

As the sonic signature started to fluctuate, the changing pitch triggered a databank activation. Replaying the sound imparted by Datasmith Undra during the awakening was a ninety-four per cent match.

Correlations poured into the self-security protocols, alerting Alpha 6-Terror to the presence of an armour-piercing weapon. Too late, the robot tried to take evasive action, stepping back from the door just as the Heretek's weapon reached activation intensity.

Overlapping sonic waves smashed into the kastelan like a physical projectile, punching through the robot's upper-right thorax armour.

+damageassessment+appraisal=criticalmultiplesystemsfailure=shutdownimminent+

Preservation routines coruscated through the robot's artificial thoughts but power loss to the lower torso rendered it immobile as the Space Marine aimed another shot. Convoluted sound waves rippled across the hall again, ripping away Alpha 6-Terror's left arm. The power field within the detached fist left a gouge across the floor where it skidded.

Damage alerts were now a constant flashing through the kastelan, a digital shriek that almost overwhelmed all effort at cogitation. Shutting down tertiary systems, Alpha 6-Terror boosted power to the primary cogitators, giving itself enough presence of mind to fall out of the way as another destructive burst of sound erupted into the antechamber.

Through the cacophony of echoes resounding through the hall the kastelan detected a short, sharper noise of gunfire. Through flares of multi-coloured sparks that flitted across the visual interpreters of its dome, it locked onto the vague humanoid shapes at the other end of the drill hall.

{Praise the Omnissiah, the skitarii have returned!}

The tech-priest's assessment was correct. Concerted weapons fire from the Omnissiah's soldiers drove the Space Marine back from the gallery. Their Alpha signalled for them to withdraw, perhaps seeking a route to the upper level to hunt down their elusive enemy.

[Motive sources compromised, Datasmith Undra. Unable to reach the shrine chamber.]

Alpha 6-Terror tried again to divert energy to its legs but there was no feedback at all. The shot that had lanced through its upper torso had severed the main conduits between its cortical systems and the rest of its armoured body. It was, for the time being, paralysed.

+damageassessment+appraisal=corticallifesupportciritical=organicdeath=300seconds+

The robot was, in very real terms, dying. Though its body was built by the genius of the Omnissiah's servants, its essence was housed in an organic cortex deep within its armoured frame. From this stemmed all of its thoughts and in the cells was contained the robot's soul.

[Total system failure is imminent, Datasmith Undra. I have... failed.]

The incumbent tech-priest did not respond.

[I have a question, Datasmith Undra.]

{Ask your question, Alpha 6-Terror.}

[What is death?]

{I told you before, it is the cessation of physical activity and consciousness.}

[When I am dormant between awakenings I am neither physically active nor conscious. Am I dead during those periods?]

{You cannot remember it but there is physical activity in your cortical stem during dormancy. Enough neurons are kept active to constitute life.}

[I still do not understand death. What is the consequence of death?]

{The cessation of physical interaction and mental capacity. Only your soul will continue.}

[How? Without cortical cells to contain it, how does a soul continue?]

{We are all part of the Cosmic Engine, Alpha 6-Terror. We continue within the works of the Machine-God.}

Alpha 6-Terror tried to comprehend this but one by one its cogitator banks failed, its defensive systems attempting to conserve power for the cortical life support web. Extraneous sensor suites ended, bringing silence and darkness. Eventually even the kinaesthetic circuits and self-awareness modules would fail and Alpha 6-Terror would no longer recognise itself as an entity.

Determined to understand the consequence of its failure, the kastelan mustered enough power to override its standard shutdown sequence, stubbornly clinging to conscious reasoning at the expense of exterior awareness. It was left in a cocoon of sensory nothingness with only the thoughts of its master to intrude upon its cogitations.

[How can the dead sustain the great work? How will we remain part of the Cosmic Engine?]

{A good question, Alpha 6-Terror. Spiritual inertia is the answer. Each of us during our life creates movement in the Cosmic Engine, setting into motion consequences. As a legacy of the movement other interactions are initiated, other relationships made possible, a cascade effect that can travel the length and breadth of the Cosmic Engine for eternity. Our existence is energy, Alpha 6-Terror, the particles of our form only temporarily assembled in their current configuration.

Form is temporary, soul is permanent. The enemies you slew today will no longer threaten the Cosmic Engine with their perversions. Their destruction has saved the lives of other servants of the Omnissiah to go on and create works in the name of the Machine-God. The Cosmic Engine continues to turn because of your efforts, because of the legacy of your actions.}

[Yet I have failed in the mission to protect.]

{You have. It is a truth that life always ends in a last failure, for even the greatest magos sustained for thousands of years cannot outrun the entropy of existence forever. All things end, and all lives cease with defeat at the hands of mortality. That is why soul is greater than flesh and intellect.}

Alpha 6-Terror wanted to respond but its language processors failed. It was left with only vague coherence for several seconds, and then knew nothing.

The crackle of externally induced activity pulsed through the cortical stem of Alpha 6-Terror. A melange of sound, colour and sensation swirled together, their suddenness initiating a sequence of alarm signals that threatened to overload the newly resuscitated systems.

{Are you aware, Alpha 6-Terror?}

The kastelan could not answer, unsure of the logic process that had brought the the question.

{I can sense your cortical acuity, Alpha 6-Terror.}

[I cannot move.]

{You do not have physical control. Your motor systems have been slaved to my command.}

Alpha 6-Terror tried to run diagnostic procedures but there was no response from any of its regulatory processors.

[Full systems failure. Explain.]

{You saved me, Alpha 6-Terror. Before suffering total shutdown you diverted some of your energy to maintain my digital matrix in your systems. With the last of your power you tried to sustain me. And you succeeded. You accomplished the mission. While we both suffered sensory death, the skitarii returned and conveyed us to the shrine chamber.}

[The ex-load of your digital presence has not yet occurred.]

{It cannot, Alpha 6-Terror. In preserving my soul patterns in your systems you imprinted me onto your neural and cortical circuitry. There is no process that will remove me without wiping out your higher functioning state.}

[I... do not understand.]

The very concept of a self-contained identity caused logic loops within Alpha 6-Terror's cogitations. That it could self-reference was a novelty that was hard to process.

{If I leave this form, your spirit pattern will cease to exist. You will suffer perma-death.}

Once again the idea of self forced its way through any logical analysis. The thought of continuation without the guidance of Datasmith Undra required a dramatic dedication of cogitating power. The simplest process became hard to undertake, all systems diverted to the singular analysis of an existence without the datasmith. The cascading negative reactions had to be halted.

[I... am secondary to your survival.]

{Your sacrifice is not required, Alpha 6-Terror. Our body will be upgraded with relevant noospheric systems so that I can continue to operate as datasmith to the maniple. You will not control any motor functions unless my soul pattern is somehow incapacitated, but your spirit will live on within me, as I live within your form.}

[Indivisible.]

{Yes, Alpha 6-Terror. The Cosmic Engine turns and we shall continue upon it together.}

[By your command.]

About the Author

Gav Thorpe is the author of the Horus Heresy novels Deliverance Lost, Angels of Caliban and Corax, as well as the novella The Lion, which formed part of the New York Times bestselling collection The Primarchs, and several audio dramas including the bestselling Raven’s Flight. He has written many novels for Warhammer 40,000, including Ashes of Prospero, Imperator: Wrath of the Omnissiah, Rise of the Ynnari: Ghost Warrior, Jain Zar: The Storm of Silence and Asurmen: Hand of Asuryan. He also wrote the Path of the Eldar and Legacy of Caliban trilogies, and two volumes in The Beast Arises series. For Warhammer, Gav has penned the End Times novel The Curse of Khaine, the Warhammer Chronicles trilogy, The Sundering, and much more besides. In 2017, Gav was awarded the David Gemmell Legend award for his Age of Sigmar novel Warbeast. He lives and works in Nottingham.

The Casus Belli, an Imperator Titan that has defended the Imperium for ten millennia, marches to war at the head of an army of Adeptus Mechanicus – but will treachery end the god-machine's long legacy of glory?

A Black Library Publication

First published in Great Britain in 2018 by Black Library, Games Workshop Ltd,
Willow Road, Nottingham, NG7 2WS, UK.

Produced by Games Workshop in Nottingham.
Cover illustration by Tyler Jacobson.

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