He placed both hands either side of the lectern and simply said, 'Fire.'

The Vae Victus shuddered as her prow bombardment cannon unleashed a building-sized projectile from its flash-protected barrel. Travelling at phenomenal speed, it closed the distance between the Vae Victus and its target in less than a minute.

The target point had been carefully selected: the weakest point of the refinery's armour, where an explosion would cause the most damage to the internal plasma tanks. Packed with millions of tonnes of highly volatile hydrogen-plasma compound, the refinery vessel was now a gargantuan flying bomb. The shell from the bombardment cannon struck it amidships, punching through metres of thick reinforcement, a delayed fuse ensuring that it did not detonate until it was deep within the heart of its target.

The shell exploded within the largest of the plasma tanks, instantly igniting the unstable compound and setting in motion a chain reaction like the one that had destroyed the third refinery in orbit around Yulan.

As though sensing the danger, the hive ship released its grip on the refinery, but by then it was already too late. Millions of tonnes of flammable chemicals ignited and exploded like the birth of a new star. Every creature attacking the refinery was incinerated, the fireball expanding in a lethal wave front and engulfing countless other swarm creatures. Kraken, drones and spores were all burned to death in the initial fireball and thousands more suffered fatal concussive injuries from the massive blast front that followed the detonation.

The hive ship had spent millennia traversing the void between galaxies and its hide was as thick as any starship's armour, but even it was helpless in the face of so much ferocious energy. Its entire body vanished in the initial fireball, its remains blasted to atoms by the Shockwave that followed in the wake of the fiery explosion.

In a fraction of a second, a creature that had taken centuries of years to grow and evolve into its current form was obliterated and wiped from the galaxy as though it had never existed.

For the ninth day in a row, the defenders of Tarsis Ultra collapsed in weary resignation. Learchus watched them, a fierce pride burning in his chest as he saw the last man drop to his haunches and remove his pack. He himself had not even broken a sweat, but his physique was such that he could have run for days before requiring any rest. He smiled as he wandered through the exhausted soldiers, aware of their angry stares and muttered curses.

The men of each regiment were performing well and a shared sense of comradeship had flourished in them all. That it had come about through a shared hatred of him did not concern him, he knew it was a passing thing. While the enemy was still distant, soldiers needed a common target for their hate and their aggression. Learchus vividly remembered Chaplain Clausel at Agiselus and how much he had hated him during his training. Clausel was now a trusted friend and mentor and had brought great spiritual solace to the men of Fourth company in the dark times of its long, proud history.

Major Satria staggered towards Learchus, his face red and streaked with sweat.

'Damn, but you're working us hard,' he gasped.

'The tyranids will work you harder,' said Learchus.

'True,' nodded Satria, bending over and resting his palms on his knees and sucking down great draughts of cool air. The major had lost weight and, since the training had begun, had shed the silver breastplate and peaked cap his rank entitled him to. His shoulder-length black hair was slicked with sweat and there was more of a swagger in his step now.

Orderlies and volunteers from the citizenry of Erebus began circulating among the panting soldiers, distributing hot food and potable water from sloshing drams. Dehydration among the soldiers had become a serious problem, with many simply eating unmelted snow, which could contain disease and dangerously lower the body's temperature.

Learchus had also put a stop to the men's rations of amasec, caffeine and bac-sticks. All these vices made soldiers susceptible to dehydration and though it had almost caused a riot when first announced, Learchus knew that his decision was paying off as the number of reported dehydration injuries had dropped significantly.

Cases of foot-rot had been widespread in the early days of training, with the thick, rubberised boots of many of the soldiers trapping the moisture of their sweat and causing necrotic fungal growths to fester. Soldiers from the Logres regiment had allowed the design of their standard issue footwear to be copied by the factories of Erebus and within days, each company of soldiers was issued with dozens of pairs of socks, anti-fungal powder and brand new boots that allowed the pores of their feet to breathe.

Learchus had been impressed by the efficiency of Sebastien Montante, the Fabricator Marshal of Erebus. He had judged him an empty headed fool when they had first met. Though he was no soldier, the man's talents for organisational logistics was second to none and virtually every request Learchus had made for supplies or equipment had been met within hours.

Montante was proving to be a valuable ally, but the same could not be said for every member of the Council of Industry who helped govern Erebus. Only three days ago, Learchus had sat with the nine members of the council in the Chamber of the Mosaic, outlining his plans for the defence of the inner reaches of the valley. He remembered the shame of losing his temper at their foolishness. The foolishness of one member in particular.

Simon van Gelder.

The man Learchus had prevented from leaving the city carried the weight of his humiliation around his neck and was determined to return the favour.

'We simply cannot allow Sergeant Learchus to demolish the buildings between the walls,' said van Gelder, sipping his wine. 'Why, when the aliens are driven off, we will be penniless paupers, lords over a rained city with nothing but its wreckage to call our own.'

'If you do not destroy them, you will have no city at all,' explained Learchus.

'The many years of peace we have enjoyed have made us complacent,' put in Montante, gesturing at the walls around them. 'Look at the mosaic here. It is clear from this that we should not have been so reckless in our building programs. The original city plans, designed by Roboute Guilliman himself, show us that there should be no structures in these areas.'

'Pah,' snapped van Gelder, with a wave of his hand. 'A faded mosaic, thousands of years old, is no basis for forcing us into economic rain, Sebastien. What will we do when our brave defenders defeat the tyranids? How can we produce goods with no manufactories?'

'Simon, we can rebuild,' said Montante. 'But we must be alive to do so. Please listen to Sergeant Learchus.'

'Many of the buildings you own have been constructed too close to the walls, Mister van Gelder. If we are forced to pull back from a wall or the tyranids capture one, then we will be providing them with valuable cover under which to approach.'

'You speak of the regions around District Quintus? These regions are over thirty kilometres from the valley mouth. Do you mean to tell me that you expect these damnable aliens to breach our fair city that far? That you don't have the ability to stop them before that? Forgive me, but I had thought the Ultramarines to be warriors of great strength and courage. It would seem I was misinformed.'

Learchus surged to his feet and grabbed van Gelder by the front of his robes, hauling him across the table and snarling in his face. Wine spilled over the table and a goblet shattered on the stone floor.

'You dare insult our honour?' spat Learchus. 'You would do well to consider your next words, van Gelder, for if you utter such an insult again, I will kill you.'