"Never, ever stay above ground longer than necessary. Taking cover and hugging the ground can save your life. The longer you survive, the better are the chances of you killing your enemy are."
That ran in Kovacs' head. As the apparent enemy continued to march, Kovacs took to the ground, and jumped to the nearest foxhole there was. The sergeant hadn't ordered them yet to advance. It big enough for two, at least. The Leman Russ tanks - the workhorses of the Guard, he knew - were roaring nearby, shooting with their guns, releasing impressive firepower. It reminded him of the fireworks, though the noise was almost deafening. Kovacs removed the safety, loaded and aimed towards the enemy. Although it was too long a distance for accurate shooting, he'd be ready to shoot. Or to spring into action, if they were ordered to advance. He made sure his demolitions were still strapped and safe - although it would take proper ignition to set them off, he didn't want to take any risks.
The enemies were clearly of humanoid shape, though they looked metallic. Kovacs had never heard of something like them - he had heard of the savage orks, and the devious Eldar. But these were something different. Perhaps the Mechanicus had created them, but he couldn't be sure. All he knew was that they were out for their blood, advancing with relentless marching.