Nemiel felt the rumble of the battle barge's thrusters reverberate through the deck plates as the Invincible Reason went to maximum acceleration. The battle barge and her flanking strike cruisers had adopted a wedge formation, presenting themselves as primary targets to the rebel ships. The Astartes' ships, designed to force their way through a hostile planet's defence network and deploy their landing companies, were even more heavily armoured than typical ships of the line. Jonson calculated that the enemy ships would focus the majority of their fire on the battle barge, buying his other ships precious seconds to close to effective firing range.

'Any response to our hails?' Jonson asked Captain Stenius. They had been trying to raise the Imperial authorities on Diamat as soon as they had come within vox range.

Stenius shook his head. 'Nothing yet,' he replied. 'There's signs of heavy ionization in the atmosphere, though, so we might not get a signal through until we reach orbit.'

'Atomics?' the primarch asked.

The captain nodded. 'It looks like the rebels have launched dozens of orbital strikes, likely targeting troop concentrations and defence installations.'

'Have the rebels succeeded in reaching the forges?' Nemiel asked.

'If not, they must be very close,' Jonson said. 'Otherwise those transports would have broken orbit as soon as we were detected.' He nodded his head at the telltales representing the escorting cruisers. 'They also wouldn't have left behind such a strong reserve force to guard them unless they already contained something valuable, so we have to assume that the enemy has at least managed to breach a number of the planet's secondary forges. If there are any defence forces still in action, they will be concentrated around the primary forge complex and Titan foundry.'

'Titans?' Nemiel asked. 'There is a legion based at Diamat?'

Jonson nodded. 'Legio Gladius,' he replied. 'Unfortunately, their engines are embarked with the 27th Expeditionary Fleet, far to the galactic south. On Horus's orders, I might add.'

'What does that leave the defenders with?'

The primarch paused, consulting his memory. 'Eight regiments of Tanagran Dragoons, plus two armoured regiments and several battalions of heavy artillery.'

Nemiel nodded. It was an impressive array of force. He wondered how much of it still survived. 'What forces can the forges muster?'

Jonson shrugged. 'An unknown number of Mechanicum troops. The scions of Mars are not obliged to share the secrets of their defences.' He paused, studying the plot for several moments before straightening and shaking his head. 'It's looking unlikely that the rebels will detach any units from their main body to try and intercept our escorts. They'll trust the reserve cruisers to keep them at bay, which leaves us facing no less than twelve ships of the line.'

'Ten minutes to contact,' Stenius announced. 'Orders, my lord?'

'Are the Stormbirds ready for another sortie?' Jonson asked.

'We have two squadrons ready for launch, and Amadis reports that they have one squadron standing by. Adzikel has a fire in her hangar bay from a crash-landed Stormbird. They estimate another fourteen minutes before they can resume flight operations.'

'The battle will be over in ten,' Jonson growled. 'Very well: signal the scout force and order them to ready torpedoes and prepare for a course change on my mark. Transmit the same signal to the main force, and add that no ship is to fire until ordered.'

Stenius bowed curtly and began barking orders across the strategium. On the tactical plot the distance between the two fleets was dwindling rapidly. They would be in extreme weapons range within moments. Nemiel thought back to the savagery of the initial engagement and prepared himself for the coming storm.

The main body of the enemy fleet was centred on four grand cruisers; at this range the officers aboard the flagship had positively identified them as the Avenger-class grand cruisers Forinax and Leonis, and the Vengeance-class ships Castigator and Vindicare. To either flank of this powerful group of ships were arrayed a squadron of four cruisers each: a mix of Crusaders, their hulls bristling with weapon batteries, and swift, lance-armed Armigers. Against such a force, the Dark Angels had their battle barge and two strike cruisers, plus the Avenger-class grand cruisers Iron Duke and Duchess Arbellatris and the Infernus-class heavy cruisers Flamberge and Lord Dante. Though the rebels had a clear edge in numbers and firepower, they no longer had any ships capable of launching torpedoes - a slim advantage that Jonson intended to capitalise on.

The seconds ticked by. Captain Stenius watched the readouts on the tactical plot. 'We're at extreme torpedo range,' he announced.

'Not yet,' Jonson ordered. He watched the scout force slip past the main body of the rebel fleet, still accelerating towards Diamat and the vulnerable transports.

Stenius nodded. 'Two minutes to extreme firing range.'

'Any signals from the planet's surface?' Jonson asked.

'Negative,' the captain replied.

'Very well.' Jonson turned to Nemiel. 'If we don't hear anything from the governor or his defence forces by the time we reach orbit, I'm going to send the landing force down around the main forge complex. Your orders will be to secure the forge and eliminate any rebel troops in the area. Clear?'

'Clear, my lord,' Nemiel answered at once.

The battle group sped onwards, straight into the guns of the waiting rebel ships. Two minutes later the Aegis Officer called out, 'Incoming fire!'

'All ships brace for impact!' the primarch ordered.

Lance beams leapt from the prows of the rebel cruisers, raking the void with searing beams of force. They slashed across the prow of the Invincible Reason and the two strike cruisers, causing their shields to flare with incandescent fury. Violet light blazed beyond the reinforced viewports of the bridge and a powerful blow resounded through the hull of the great ship.

'Hull breach, deck twelve, frame sixty-three!' the Aegis Officer called out. 'No casualties reported.'

Captain Stenius accepted the news with a curt nod. 'Do we return fire?' he asked the primarch.

'Not yet,' Jonson replied. He was studying the readout on the plot intently. 'Signal the scout force: come about to new heading one-two-zero and commence torpedo runs on rebel grand cruisers.'

The Astartes ships ploughed through glowing clouds of plasma and vaporised deck plating as they continued to close on the rebel ships. As they closed to optimum firing range the enemy force began a slow turn to starboard so they could bring their fearsome broadsides to bear on the Imperial ships. But as they began their turn, Nemiel saw the scouts begin their course change. The nimble escorts swung around in a tight arc directly behind the enemy ships, their presence hidden by the rebels' own reactor emissions.

The trap had been sprung. Jonson smiled coldly. 'Signal Amadis and Adzikel: target enemy grand cruisers and launch torpedoes. Captain Stenius, you may fire at will.'

More lance shots leapt from the rebel ships, and now the enemy weapon batteries were going into action as well, hurling streams of blazing shells at the oncoming Imperials. At the same time, torpedoes leapt from the tubes of the Astartes ships and the oncoming scout vessels, bracketing the rebel grand cruisers from both fore and aft.

Heavy blows pummelled the battle barge to port and starboard. Alarms wailed. 'Multiple hits, decks five through twenty!' the Aegis Officer called out. 'Fire on deck twelve!'

'Signal the main force,' Jonson said calmly. 'New course three-zero-zero. All units, target enemy cruisers to port. Fire at will.'

Wreathed in a maelstrom of fire, the Imperial ships swung ponderously to port, aiming away from the centre of the enemy formation and instead towards the four rebel cruisers on the enemy's flank. Along the dorsal gun decks of the battle barge, enormous turrets slowly traversed, bringing their massive bombardment cannons to bear on an Armiger-class cruiser. At the same time the battle barge's starboard weapons batteries went into action, hammering at the rebel ship's void shields with a hail of macro cannon shells. The enemy cruiser's shields flickered angrily under the relentless barrage before collapsing entirely. At the same time her lance batteries lashed at the Invincible Reason, raking her void shields from stem to stern. Beams of force pierced the defensive field and clawed through the barge's armoured hull.