A group of heretics was charging towards me. I took a heartbeat to line up the shot and pulled the trigger. The load of pellets ripped through the enemy, sent them tumbling back involuntarily into the mud and the latrine pit. They would not be emerging this time.

I glanced around and saw that Tomkins was down. His bayonet blade had sliced away mask, cowl and upper tunic from one of the heretics and I had a sudden horrific view of the cultist’s exposed features. His skin was near-albino white. His eyes were bloodshot and marred by tiny broken veins. Boils erupted from his skin. Red rashes ran like rivers between them. He looked as unhealthy as it was possible to be and remain mobile, and yet he fought with the feverish strength of a berserker. This was a product of the vats.

I brought the butt of my shotgun down on his head. His skull broke like an eggshell, spilling discoloured brains everywhere. Flies buzzed around him and I had the sudden violent illusion that they had been released when the bones of his head had shattered. I told myself that could not be the case and took a moment to try and understand the situation.

Most of my men were down. All of my squad and the other two squads that had been following me had been overwhelmed by the double-pronged attack from the trench and the bunker wall. A few were still fighting, but it was only going to be a matter of time before they were overpowered by the scores of heretics swarming over them. The shotgun had bought me an extra moment or two but I was going to be hauled down myself unless I did something.

Autogun bullets whizzed around me as I blasted a path to the trench wall with the shotgun, slung the weapon on its strap and hauled myself up over the lip of the parapet out into no-man’s-land. There was a small gap, a rise at the trench lip, and at the foot was barbed wire. I could see holes had been stealthily clipped through it and here and there bits of dark cloth clung to the metal spike-knots in the wire. This was where the assault team had made its approach.

I had only a second to register this and while I did I was unclipping a grenade from my belt. I lobbed it into the trench and sprang forward, half scrambling, half running along the front of the parapet in case anyone got the idea to respond in kind. A few moments later I heard the explosion rip through the trench and a fraction of a second after that I felt its vibration. I threw another grenade in and kept moving, following the line back the way I had come, hoping that all of my own men down there were already dead and that I was not killing them with my grenades.

The muddy earth sucked at my boots. My gloved hands were covered in the reddish soil where I had put them down to maintain my balance. I heard a horrible phlegmy voice gurgle out orders and saw a cowled head poke up over the parapet ahead of me. I swung the shotgun down on its sling and pulled the trigger. The head vanished in a fountain of blood and bone. I kept running, still squatting down, praying desperately to the Emperor.

The muddy earth gave way beneath my boot. I slipped, overbalanced, began to tumble down the slope towards the barbed wire. I threw myself flat, dug my fingers into the front of the parapet, slowed down my slide.