Disease would still get you.
Depends on the Location
While there were certain areas where diseases were more active, things like tyfhus and cholera were present everywhere. Throw a bunch of people together on limited space and you'll get diseases, even in the 21st century.
As I'm not physical strong but have a good marksmanship, I would probably do a good portuguese rifleman Plus I read a lot of books about military history tactics that would maybe get me up to a NCO rank, if I got lucky
I don't think knowledge of militairy history will help you in the duties of an NCO.
I love coming in this thread and just crushing dreams.