I need to know what ranks were used during ww2, but also what each rank does, such as a Pvt is just a soldier?

Question

I need to know what ranks were used during ww2, but also what each rank does, such as a Pvt is just a soldier?

Answer 1

In which army? All of them?

Answer 2

http://en.wikipedia.org/wiki/WWII_US_Arm...