Some of the corpses were already crawling with the fat-bodied bore-flies. They liked nothing more than to feast on the flesh of the fallen, before laying the jelly eggs containing their larvae.

I narrowed my eyes. A man lay with his throat cut from ear to ear, a splatter of red blood down his chest, covered in crawling insects. An officer sprawled face down, a lho-stick near to hand, a wisp of smoke still rising from the tip. A soldier with a faintly familiar face slumped over a packing crate on which lay a deck of cards and an open copy of the Imperial Infantryman’s Primer. The air inside my rebreather tasted stale. Something in my brain screamed that I ought to be able to smell the odour of death. I could hear the troops behind me shuffling their feet; all of them knew better than to get in front of me when I had the shotgun in my hands.

My brain continued to gibber. Panicked thoughts raced through it. What was I missing here? Where were the enemy? They must still be close. I checked the ridgeline of the trench. There were faint scuff marks on some of the crenulations. Maybe the assault team had come over there. Or maybe they had come down that branch in the trench. I moved slowly forward, my finger almost twitching on the shotgun trigger, the weapon heavy in my hand.

We moved along the trench beside the open sewer. Someone had been making improvements recently by the look of it. Pipes emerged from beneath the water as if workers had abandoned an attempt at plumbing halfway through the process. My brain registered that, but my eyes wandered on.

I counted corpses. Ten. Twenty. Thirty. I stopped counting. A whole platoon had gone down here and there was no sign of their attackers. With every step I felt like I was sticking my neck further and further into a trap, moving further and further away from safety. Reinforcements were getting more distant. The chanting of the heretics was getting closer.

A bore-fly landed on my goggles. More joined it. They crawled across the glass, partially obscuring my vision. I shook my head but they did not move. They were bigger than bluebottles, with bloated thoraxes and wings that seemed the same colour as the unnatural oils that floated on the surface of the chemically tainted puddles.

Had the enemy used gas? The thought sauntered across my brain.