World Wars of the twentieth century immediately led to

I'm not sure if that's exactly what you mean, but world wars of the 20th century immediately led to the indebtedness of nearly all involved countries to the United States which borrowed them money to rebuild themselves after the wars. In result it also forced those countries to "obey" the USA politics (i. e. "You owe us money, so do what we say and we'll discontinue part of your debt"). That was the general idea of bringing the wars by the USA on and it's still being partly continued in present wars against "terrorists".

That's not something you'll learn at school because they won't tell you the real reason of the wars and that's why I recommend some further research if you want to see it all from a wider perspective.