Which Genre of music does this song belong to:
What contributes to a cold and evil atmosphere, like in the following Score in the WW2 movie - Fury (https://www.youtube.com/watch?v=DRAlWtadQRc).
There's definitely an element of Gregorian Chant in there, which some may say sounds creepy on its own. The majority of it is Atmospheric, although the drums most closely resemble Marching Band or some derivative of Military.
I'd say it's a well-scored fusion of all the above styles, which produced a very effective end result.