Correction - We became a world power by smashing everyone else. The Army Air Force blasted Germany and Japan to rubble. The two atomic bombs only did 3% of the damage to Japan.
The european part of wwII was really about Germany vs. Russia.
probably 20 million dead on each side.
And russia was getting the better of germany before the USA entered.
Now the English and Americans certainly made the russian job easier by opening the 2nd front.
In the comedy Hogan’s Heros, there was a really good reason why every german in that show trembled with idea of being sent to the russian front.