That was courage indeed.

'Range to target?' asked Sharaq, fighting to keep his tone even.

The question was unnecessary. He could already see that the Imperator was less than three hundred metres away through the Manifold, point-blank range by any normal measure of things, but insanely close in this situation. He could already hear the squeal and rasp of the voids as their fields warbled with the proximity.

'Two hundred and fifty metres, my princeps,' said Bannan.

He spared a glance to his left.

Victorix Magna stood, implacable and immovable, before the marching Imperator, and Sharaq loved the Stormlord for his resolve as much as he was frustrated by his inaction. The tension within the cockpit compartment of Metallus Cebrenia was unbearable.

Then a harsh, deafening squall shrilled across the vox frequencies, a filthy blurt of continuous, corrupted code noise that sounded like throaty laughter. Sharaq flinched and his sensori screamed as the wailing shriek tore at their hearing.

'What in the name of the Omnissiah is that?' yelled Bannan, snatching the vox-set from his head.

Sharaq killed the audio as the cackling laughter code burbled over the vox and the booming warhorns of the Mortis engines echoed from the towering cliffs of Ascraeus Mons.

The Imperator lowered its weapon arms, every horn, bell and augmitter upon its colossal spires and bastions blaring in disdain. The noise was unimaginably loud, broadcast across every audible wavefront and code frequency.

Debased and dirty codelines conveyed vile algorithms that Sharaq felt worming their way into his peripherals like viral code, and his aegis protocols fought to prevent them from reaching the deep sub-systems of Metallus Cebrenia.

'Princeps!' shouted Bannan. 'Enemy course change detected.'

Sharaq gasped, his mind awhirl as his implants defended his neural paths from infection by the scrappy code fragments carried on the war-scream of the Imperator. He forced his mind through the clotted data packets of black, oozing information that blurred his vision and saw that Bannan was right.

The Imperator was changing course, its stride swinging to the east.

Like a great ocean liner travelling at speed, the course of such a vast machine did not change swiftly and its new heading would barely carry it past the south-eastern skirts of Ascraeus Mons.

'Dolun? Intercept plot,' hissed Sharaq, the beginnings of a blistering headache building behind his eyes. 'Where's it going?'

His sensori didn't answer, and Sharaq twisted his head to see Dolun lying supine on his reclined couch. The man's eyes rolled back into his skull and foaming spittle gathered at the corners of his mouth.

Sharaq meshed his senses briefly with Dolun's station, feeling the hash of viral code replicating like a plague within his I/O ports, ready to spill out into the guts of the war engine.

With a thought, Sharaq cut the link between Dolun's interfaces and the rest of the Titan, but even as he did so, he could feel the scrapcode trying to find another way in.

'Moderati Bannan!' shouted Sharaq. 'Disengage Sensori Dolun from his station. Now!'

Bannan looked over at Dolun, who was convulsing as his corrupted cybernetic enhancements began fitting with the power of a grand mal seizure. Bannan disengaged his hard plugs as quickly as he dared and lurched across the sensori station, unsteady on his feet after so brutal a separation from the MIU.

Sharaq turned his attention from the compromised sensori officer and followed his own track on the enemy engines. An overlaid map of the Tharsis Montes swam into view, grainy and washed with fragments of faulty code. A red line extended from their current position, swinging around to the north-east and extending towards the port facilities of Tharsis Tholus, the primary embarkation point of Astartes supplies from the Fabricator Locum's Mondus Occulum forge.

Sharaq dismissed the map as the shriek of voids filled the cockpit with a warbling, squealing howl of feedback. Like a million nails down a blackboard, titanic energies pushed against one another, scraping their invisible power together and sending flaring, whooping coils of colourful lightning discharge into the air.

'Sensori disconnected,' called Bannan, and Sharaq looked round to see Dolun jerking and twitching on the deck, lubricant and jellied brain matter leaking from his cranial plugs.

'Good work, Bannan,' said Sharaq. 'Leave him and get back on station.'

Sharaq returned his attention to the Manifold, watching in ashamed relief as the might of the Imperator swung yet further away and the spine-shearing sound of void interference abated.

'All Tempestus engines,' he said, forcing a channel through the howling static that still laced the airwaves. 'Ease weapons, I repeat, ease weapons. Mortis are turning away! Acknowledge!'

One by one, the affirmations of the Tempestus engines appeared on the Manifold, and Sharaq let out a shuddering breath as he realised how close they had come to igniting a shooting war on the surface of Mars.

The Imperator's escort of Warlords moved with it and the war machines of Legio Mortis began tramping away, each step carrying them further from the domain of Tempestus.

Mortis was leaving, but Sharaq wanted to be sure they weren't about to turn back for another provocative pass.

'Raptoria, Vulpus Rex, follow Mortis and make sure they keep on their way,' he ordered, wondering why the Stormlord was not issuing the order himself. 'Keep a safe distance back, but make sure they go.'

The two Warhounds set off without bothering to acknowledge his order, and Sharaq slumped deeper into the moulded leather of his reclined seat. Sweat coated his brow and his hair was soaked. He closed his eyes for a second, shutting out the data noise of the Manifold and letting the human part of his mind process the near calamitous events of the past few minutes.

Had it really been so short an engagement?

He opened his eyes as the nagging static of the vox remained unbroken by orders, information requests or any form of leadership from Victorix Magna.

Sharaq looked over to the Stormlord's engine, a terrible sense of dread building in his gut as he saw that Victorix Magna remained as she had since taking up station before the Imperator. That dread built as he saw fluid drooling in a black rain from her torso and that the hissing plumes of superheated steam that ought to gust like breath from exhaust vents beneath her shoulder carapace had ceased.

The engine's head was bowed, her limbs slack against her sides.

'Victorix Magna,' called Sharaq over the Manifold, his fear rendering his communication sharper than he intended. 'Princeps Cavalerio, please acknowledge.'

There was no response.

'Stormlord, please respond immediately!'

A shift of view in the Manifold and Sharaq's head sank to his chest as he inloaded the auspex readings of the Stormlord's mighty engine Victorix Magna was dead.

Thousands of kilometres to the south of the confrontation between Mortis and Tempestus, deep in the desolate, empty wilderness of the southern pallidus, wind-borne ash blew across the cratered wastelands at the edge of the Daedalia Planum.

Even further south, the horizon burned with colourful fire, the skies striated with chemical pollutants and reeking gases expelled from the massive refineries that encircled the planet's equator.

Only the hardiest scavengers attempted to eke out a living in this region of Mars, the spoil pickings usually too thin and too laden with toxins to be of any real use. One such scavenger was a man named Quinux, a wizened prospector and former Skitarii whose body had rejected the gross implants necessary for full assimilation into the ranks of the Mechanicum's soldiery.