His voice became a growl matching the protests of his armour as he struggled against the drag of the mud. He went over the edge of the river bank proper, hidden by near two metres depth of liquid soil, and the mud suddenly deepened to his neck. Felix half swam forwards. A dead man bobbed to the surface with a sucking belch, his rotting head lolling on his neck. There were many dead there, decaying into the mud sea, their flesh becoming part of it. All were mortal human soldiery. The diseases the enemy spread hit baseline humans hard.

Felix found himself struggling through a reef of bones; liquefied flesh clung to his armour. He sealed his breathing grille against the stench and kept his eyes forward. Espandoria Tertio had been occupied by the enemy for months. Liberating it would repay these dead souls for their sacrifice in protecting it.

Keep your eyes forward. Look at what is to come, he told himself. The past is dead, the present nearly so. Only in the future is there life.

The unknown awaited them. Orbital pict-capture of Espandoria Tertio had been impossible through the thick clouds of flies that masked the city in all weathers. Other mechanical auguries met with the same lack of success. Psychic probing yielded only maddening visions for those psykers brave enough to try. Not even Lord Tigurius or Codicier Maxim had had any success. Mortarion’s clock would have to be found on foot.

More than a few senior Space Marines had opined that the population was long dead, and that the city should be levelled from the void. Guilliman had met with them all, and told them they were wrong. He had commanded a ground assault to clear the enemy away. He had given a speech condemning any man who would level an Imperial city while its citizens might be alive. Privately, he had confessed to Felix that the others could well be right. But the city must be taken, for they must be assured that Mortarion’s warp clock was destroyed.

Felix was not sure which factor was the most important to the primarch. Mortarion could withdraw his device anyway if the battle went against him. He was part daemon, so they said, and no longer bound by the universal laws. Guilliman had pulled medicae teams from across the sector to treat any of the city’s population who might have survived. The truth was there was little to choose between either as justifications for the battle. They were worthy aims. Guilliman wished to fulfil both. That was what anyone would have expected from the primarch.

At that moment, Guilliman awaited in orbit aboard the Macragge’s Honour, directing the operation and trusting to his ground troops to locate Mortarion’s device and broadcast a teleport locus to him.