Little story I was thinking of for my (small) 40k Army, the 4/42nd Krieg Siege Regiment.
Private Oscar looked over at the group of guardsmen, each one wore a long coat, each one wore a gas mask. His unit, the 242nd Cadian Infantry Regiment, had been devastated in the recent fighting. Rather than reforming the unit, the few survivors had merged with the the 4/42nd Krieg Siege Regiment.
Oscar looked down at his uniform, the green fatigues standing out amid the dull grey outfits of the Kriegsmen. He didn't know much of the Kriegsmen, besides stories of their dedication and almost fanatical loyalty. He had tried to talk to the Kriegsman next to him, but only received a blank stare from the gas mask, the blue eye pieces hiding the guardsman's eyes.
Suddenly, the entire line snapped to attention, pulling their lasguns to their shoulders, and staring straight ahead. Oscar did the same, then felt his blood run cold when he saw why.