He grunted in satisfaction and pulled hard on the chain, shouting, 'Spirits of war and fire, I invoke thee with the wrath of the Machine God. Go forth and purify!'

Steam hissed from juddering pipes and a high-pitched screech filled the weapon chamber as the gravometric impellers built up power in the breech.

Mabon rushed to the edge of the gantry and gripped the iron railings. Seeing a weapon of such power discharge was a potent symbol of the might of the Imperial Navy and he never tired of the sight.

The screeching rose to an incredible volume, though Mabon was oblivious to it, until the nova cannon fired, and the enormous pressure wave slammed through the chamber. The weapon's firing sent the three-hundred metre barrel hurtling back with the ferocious recoil. The air blazed with sparks and burning steam as the grease coating the rails vaporised in the heat of the recoil, the stench of scorched metal and propellant filling the chamber with choking fumes.

Mabon roared in triumph, gagging on the stinking clouds of gas that boiled around him.

Juddering vibrations attempted to topple him from the gantry, but he had long since grown used to them and easily kept his balance.

The smoke started to clear and his gunnery overseers began whipping their gangs into dragging the massive weapon back into its firing position once more. The armoured bays in the floor groaned open and the looped chains descended to be attached to a fresh shell.

Mabon had drilled his gunnery teams without mercy and he prided himself that he could have the nova cannon ready to fire again within thirty minutes. This time would be no different.

The shell from the Argus streaked like a blur of light through space, exploding like a miniature sun in the heart of the tyranid ships. More potent than a dozen plasma bombs, the shell detonated only a few kilometres from one of the manta-like creatures, instantly incinerating it in a roiling cloud of fire, which also scattered a nearby flotilla of smaller creatures. One creature fell away from its pack, glutinous fluids leaking from its ruptured belly. It thrashed as it died, eventually becoming still as it haemorrhaged fatally.

The swarm scattered from the blast, though a host of small organisms, each no larger than a drop pod, converged on the shrinking cloud of organic debris, exploding with terrific violence as they neared the centre of the blast.

A group of creatures surged forward, as though galvanised into action by the blast, and closed on the approaching Sword frigates. Behind the frigates came Sword of Retribution, the Cobras of Cypria squadron and the strike cruisers of the Ultramarines and the Mortifactors.

First blood had gone to the Imperial fleet, but the battle had only just begun.

Uriel gripped the hilt of his power sword, listening to the sounds of the Vae Victus as her hull groaned and creaked as she manoeuvred in the battle line. The lights in the corridor were dimmed as he and his squad waited in one of the strike cruiser's reaction points. When going into battle, the Space Marines aboard a ship of war were stationed throughout the corridors of the ship in places where enemy forces were likely to try and board.

His helmet's vox-bead was tuned to the ship's bridge and he could hear the excited chatter of the various captains travelling between their ships. He listened to the cheers as it became apparent that the fleet's flagship had just scored a direct hit on an enemy vessel with her first shot. Such an auspicious beginning boded well for the coming engagement, though Uriel could not rid himself of feelings of apprehension.

He did not like the arbitrary nature of space combat, where a warrior's fate was in the hands of others, no matter how skilful or competent they might be. Uriel knew he would rather face a thousand enemies on the field of battle than wait in the sweating darkness of a starship, not knowing whether death would reach out its long, grave-dirt encrusted fingers and sweep its terrible scythe around to claim his soul. He shuddered at the thought.

Pasanius saw him shiver and said, 'Captain?'

Uriel shook his head. 'It's nothing, I just had a strange sensation of deja vu.'

'Are you getting another one of your "feelings"?' asked Pasanius.

'No, do not worry, old friend. I just do not like the idea of waiting here for a foe who may not come. Part of me wishes I had stayed with Learchus on Tarsis Ultra.'

'Now I know you're insane,' joked Pasanius. Though the rivalry Uriel and Learchus had endured on Macragge during their training had long since been forgotten, they would never be true friends. Where Uriel had learned the virtue of personal initiative from his mentor, Captain Idaeus, Learchus seemed incapable of making that leap. He was an Ultramarine and that was to be expected, but Uriel knew that there were times when such rigid stricture was not always the answer.

Such thoughts disturbed Uriel. He knew it was but a short step from there to beginning down the path of the Mortifactors. Was that how their descent had started? Small breaches of the codex's teachings that over the centuries became greater and greater until there was nothing left of the blessed primarch's work? Astador had claimed that their Chapter venerated the primarch, but could you hold him highest above all else and yet not follow his words?

Had Idaeus been the first step towards the end of everything the Ultramarines held dear? Could he have been wrong in his teachings, and was Uriel on the path that lead to ultimate damnation? Already he had gone against the teachings laid down in the codex, most recently on Pavonis.

In the dim light of the Vae Victus, Uriel felt the stirrings of doubt for the first time in his life.

Aboard the bridge of the Sword class frigate Mariatus, Captain Payne watched the tyranid bio-ships closing on his vessel with a mixture of anticipation and dread. It stunned him that creatures so huge could be alive, though he assumed that, in the way of the larger beasts on his homeworld, they would be as stupid as they were massive.

A clutch of drifting objects floated before the bladed ships, pulsing ahead of the alien vessel as it continued closing the distance between them.

The captain folded his arms and nodded to where his gunnery officer stood by the weapons station.

'You have a firing solution?' he asked.

'Aye, sir, the lead enemy vessel will be in range in just under a minute.'

'Very good. Order all ships to begin firing as soon as the enemy ships are in range.'

Payne marched back towards his command chair, perched atop a raised dais at the centre of the bridge. He followed the progress of the other ships in his squadron, Von Becken and Heroic Endeavour, on the pict-slate before him, satisfied that they were holding proper station - allowing their leader to take the first shot. A shiver of premonition went down his spine as he watched the creatures before his ship turn ponderously to face him and he felt he could see their dead, expressionless eyes staring deep into his soul. Such a notion was plainly ridiculous: these beasts would have been blinded by spatial debris were they to rely on sight alone. But still the notion persisted and he bunched his fists to halt the sudden tremors that seized him.

'All guns firing now,' reported the gunnery officer calmly as the ship juddered with the recoil of its powerful guns. The vibrations running along the worn teak flooring did not do justice to the violence of his guns' firing. Right now, hundreds of massive projectiles and powerful lasblasts would be hurtling through space to unleash a torrent of explosive death amongst these vile aliens.

He watched a flurry of detonations explode around the nearest bio-ship, gradually drawing in as his gunners bracketed it. Some even managed to score direct hits, their shells blasting one of the creature's giant, bladed limbs from its body. Vast streams of fluid pumped from the bio-ship's innards as the remainder of his squadron opened fire and the flash of distant explosions momentarily obscured the tyranid ships. When the viewing bay cleared, he saw that one had been completely blown apart and another was drifting listlessly in space. He surged from his chair and punched the air in triumph.