The slow died almost instantly. The quick and the lucky managed to scramble into the trench system that was spreading out from the bridgehead. Where there was open ground they made trenches out of the dead – a stinking mass of bloated bodies, pools of gore and rotting guts. They were piled up in low walls of hollow eyes, tongues hanging out of slack mouths, lifeless hands clutching those who passed.

The traitors clung on tenaciously, but they had been driven back, trench by trench, until the Imperials were right at the bottom of the defences of Tor Tartarus. With bodies and with picks and shovels, Imperial forces established dug-outs and bridgeheads that went right up to the skirts of the bastion.

On the second morning, fresh assaults were launched. Some were driven with frenzon, others with religious zeal or a guilt that had been whipped into a hatred of all life, especially their own. They hurled themselves into furious cross-patterns of las-fire.

Bendikt was impassive as he reviewed the reports of death and slaughter. At the description of the barricades of bodies he nodded slowly. ‘See, Mere! I told you so. Even after death, the penal legions serve a function. They keep the living alive.’

By noon on the third day the supply of reinforcements slowed, as the chief logistician’s plans began to take the strain. The attacks had faltered and the defenders sallied out, driving the desperate penal legions back onto the guns of their overseers.

As evening on the fourth day fell, each side scrambled to reinforce their front-line trenches, and renewed flights of Colossus Marauder bombers pounded the upper defences with bunker-buster shells.

Bendikt did not like to waste words. He paced up and down over the map of the battlefield. All about Prassan the command staff were intent on their jobs, some marshalling counter-attacks, others directing artillery fire or liaising with troops on the ground, while Prassan was responsible for recording casualty figures.

‘Please confirm that,’ Prassan said as the number of fatalities was relayed to him.

The vox-officer for the first penal division was at the front. Prassan could hear the rumble of explosions in the background.

The numbers were apocalyptic. Even for a Cadian they seemed impossibly extreme. ‘You are sure?’ he said after a long pause.

‘Yes, I’m damned sure,’ the penal officer responded.

Prassan added the total to his list. The next vox-officer was another penal legionnaire. Every second word was an expletive. Prassan was sceptical until he saw pict-images flickering on the dataslates that showed piles of the dead, lined up like sandbags across the boarding ramps, squads being mown down by withering defensive fire, torrents of blood filling the drainage channels along either side of the assault ramps.

He felt somehow responsible. His hands were covered with sweat and they stuck to the papers. He felt sick as each hour rolled past and he marked lists of regiments as effectively destroyed.

He stopped questioning the figures.