Heinrich sneezed as he was in the middle of finishing up construction efforts on the fortifications established outside the now vacant city of Belgrade. He had a hard time with what had been done to the Serbian Capital, specifically all the residents inside of it who had passed away.
Under the orders of his commanding officer, roughly a hundred thousand innocent lives were terminated in the blink of an eye, and in the most horrific way imaginable. Mustard gas was particularly nasty. There were plenty of better ways to go that was for sure.
Other chemical weapons of the era would suffocate you to death, but Mustard Gas was a blister agent, causing intense burns to the inside and outside of one's body until they were no longer recognizable as human.
Purging the gas had which sank into the depths of the city had been a task of itself. Then came removing and disposing of a hundred thousand bodies. I mean how did one even go about that? Cremation was impossible.