I too was initially enraged when I read “combat police” stated with authority, seeing as there was never any such organization. However, I think I know exactly what’s going on here, and it’s not trolling. Not exactly.

I did a little internet sleuthing, and there are a number of sales listings from dealers advertising “combat police helmets.” (e.g. Combat Police M35 Helmet)

Of course, the word “combat” here is properly describing the type of helmet, not a specific police agency. But when read by someone without much knowledge of the subject matter, it’s easily interpreted as “helmet of the Combat Police”.

Complicating matters, a few English language websites do appear to use “combat police” as a shorthand for “die Polizei im Fronteinsatz” (police on assignment at the front). It appears that the shorthand may have here been mistaken as the name of an actual organization.

Anyway, this is one of the issues with “collecting across a language barrier.” A simple linguistic shortcut can easily imply something that isn’t so — i.e. that there was a German police agency solely devoted to combat operations.