Both were painted in the sea green of the Sons of Horus, their frontal glacis emblazoned with a flame-coloured eye. The speeders paused, like sniffer dogs hunting a scent, but Remus knew these mountains well and had placed his kill teams with perfect cover. No matter how sophisticated the speeders’ surveyor packages were, they wouldn’t find his warriors.

The speeders carefully eased their way into the canyon, swiftly followed by a five-strong squad of bikes, each one heavily armoured and fitted with forward-firing bolters. A black banner decorated with yet another eye symbol flapped behind the lead bike, and Remus fought the urge to open fire on these invaders.

Then the tanks came, a pair of Rhinos, swiftly followed by three Predators and the grumbling monster of a Land Raider. Another three Rhinos followed it, and yet another pair of Predators formed a rearguard. Barkha had called this a small force, and measured against the scale of warfare a Legion could put in the field it was, but this was still a formidable display of firepower.

The bikes and speeders moved off, and Remus knew they were never going to get a better chance than this. He pushed onto his knees and sighted down his bolter at the pilot of the nearest speeder. He squeezed off a round, and was rewarded by a kill signal in his helmet. The vehicle slewed away as the pilot slumped over his controls. Remus’s shot was the signal to his ambush force, but before a single shot could be fired, a booming volley of gunfire sounded from higher in the mountains.

Remus saw his men die in droves from the deadly accurate fire, and spun to see dozens of muzzle flashes from the rocks higher in the mountains. Ultramarines icons were winking out on his visor, and his moment of paralysed shock almost cost him his life. His armour registered two impacts, both glancing and not serious enough to hamper him, but he dived into the cover of the stacked cairn.

‘Barkha!’ he yelled, returning fire uphill. ‘Do you have a visual?’

‘Affirmative,’ came the sergeant’s harried voice over the vox. ‘Sons of Horus infiltrators. Squad markings match those on the vehicles below.’

Remus was stunned at this turn of events. How could the Sons of Horus have gotten behind them? How had they known the Ultramarines were lying in wait for them?

Furious exchanges of gunfire flickered back and forth between the two forces, and Remus knew the vehicles below would soon be adding their own weight of fire to the fight. The ambushers had been ambushed, and there was no sense in continuing an engagement that was already lost. The primarch’s words on the subject were abundantly clear.

When they have the drop on you, don’t draw.

‘All units,’ ordered Remus. ‘Withdraw and regroup. Rally point Ultima Sextus. Go!’

REMUS BOUNDED FROM cover to cover, firing as he went. He had no time to aim, and just had to hope that his wild shots hit one of these Sons of Horus bastards. He heard the bark of gunfire all around him, punctuated by the roar of vehicle engines and the crash of artillery pieces launching arcing volleys of shells. A ragged group of Ultramarines ran with him, an amalgamation of three squads he’d gathered after the rout from Konor’s Gate further down the mountains.

Every move they’d made, the Sons of Horus had countered or circumvented. It had been humiliating to find that every recourse to his primarch’s words had resulted in dismal failure. Remus despaired of winning this fight, but had to keep faith that some grander stratagem was yet to reveal itself.

Bolts of light streaked overhead, withering storms of las-fire as helots traded fire with forward units of the Warmaster’s army. Remus had no tactical view; a shot from a Sons of Horus sniper had damaged his helmet beyond repair and so he had discarded it three kilometres back. To fight with his head unprotected was an alien sensation to Remus, denying him access to all manner of battlefield information, but the connection to the visceral nature of the fighting couldn’t be denied. To smell the acrid reek of propellant fuel, the backwash of shellfire and the burnt air taste of las-fire was a powerful kick in the guts to keep your head down.

Sweat streaked his face and black dust covered his scalp. Above him, the sky was a swirl of colourful streaks of gunfire and arcing explosions. The noise was unlike anything he had experienced before, a mix of snapping small-arms fire, mixed with the deeper bangs of close-firing heavy guns.

Sergeant Archo crouched in a makeshift trench; his warriors taking cover beneath its firing step as the Sons of Horus advanced behind a creeping barrage of artillery. Just like in the canyons to the south, the Warmaster’s forces had consistently blindsided the Ultramarines, which seemed so absurdly improbable, that Remus wondered if this was not some hideous nightmare from which he could not awaken.

He risked a glance over the rocks, seeing a grimly advancing wave of warriors armoured in the colours of the Sons of Horus. Each bore the eye of Horus device upon their chest, and that same symbol was repeated on the banners flapping from the aerials of the hundreds of armoured vehicles pouring fire uphill.

‘Not so fancy now, are they?’ said Barkha, dropping in beside Remus. Like the captain of the 4th Company, Barkha had removed his helmet, his leathery skin tanned almost black and his hair bound in tight cornrows to a short ponytail at the nape of his neck.

‘They don’t need to be,’ replied Remus.

‘What do you mean?’

‘Exactly what I said. We’re all out of options. The Warmaster has a knife to our throat, and he has no more need for subtlety. This is the death blow.’

‘Truly?’ said Barkha, and Remus saw the fear of that fact written all across his face. ‘We must have some plan to meet this attack?’

‘Then tell me what else we can do? Every stratagem has been met and countered. Every subterfuge of war has been anticipated and defeated. All we can do now is fight like true warrior kings of Ultramar and take as many of the bastards with us as we can.’

‘But the primarch must have considered this situation,’ pressed Barkha. ‘You must have misread his words or issued a wrong order. That’s the only way we could have been brought to this.’

Remus shook his head. ‘You think I haven’t thought that since this engagement began? I’ve been over it all a hundred times, and I forgot nothing, misread nothing. We did everything that could have been done.’

‘Then how has it come to this?’

‘Because there are some things that can’t be met with plans and preparation,’ said Remus. ‘Some warriors are clever enough to ram a speartip through the spokes of any plan, no matter how brilliantly conceived. The Warmaster is such a warrior.’

‘But Primarch Guilliman…’

‘Does not fight with us,’ snapped Remus. ‘Now stop talking and start killing!’

STEP BY BRUTAL step, the Ultramarines were pushed back up the mountains, leaving thousands of fallen warriors in their wake. Every metre gained by the Sons of Horus was paid for in lives, but Remus had been right; this wasthe death blow.

With the Fortress of Hera at their backs, the defenders of Macragge prepared for their last battle. To yield the land of their forefathers without a fight was not the Ultramarines way, but the time was almost at hand where they would need to face the Warmaster from behind marble parapets and towers of gold and silver. If this was the end then it would be the most glorious end imaginable.

Remus had volunteered the 4th Company to act as the Ultramarines rearguard, and they took position on the Via Fortissimus, the great road that led from the plains below to the mighty bronze gate of their Legion fortress. Behind them, the depleted ranks of the Ultramarines battle companies that still survived all but fled to the transient safety of the Fortress of Hera.