In my humble opinion; unlike WWI which was the War To End All Wars and indeed saw the advent of machine gun slaughter, early aerial bombardment of cities and horrific WMD's (gas attacks), WWII merely:
resulted in over 100 million dead and over 250 million casualties.....
redrew the map of the world and impacted every country and peoples on earth....
changed warfare in 6 years from primitive mechanized cavalry to atomic combat....
evolved from biplanes used in many prewar air forces to early almost-ICBM's (V2's) with the "New York Rocket" under development....
restructured the worlds military, logistical supply chain and command structure.....
put 12 million Americans alone in uniform.....
resulted in at least 4 countries exceeding 20 million dead (Germany, Russia, China and Japan).....
created countless new manufacturing techniques, technological changed and food production methods.....
invented synthetic rubber, gas, plastics, fissile materials, etc.....
and on and on and on.......
also, created the trick question:
"Quick....how many Frenchmen does it take to defend Paris?"
"I don't know, it's never been tried"
Here is the 1940 Tour De France