jesus says

so world war two just didnt happen or what?

Prayer assumes that the minds behind WW2 were clean by post Abrahamic/Christian standards.

Titus 1:15-16~ Unto the pure all things are pure: but unto them that are defiled and unbelieving is nothing pure; but even their mind and conscience is defiled.
They profess that they know God; but in works they deny him, being abominable, and disobedient, and unto every good work reprobate.