Classic post hoc ergo propter hoc fallacy. There has also not been a world war since the invention of the miracle bra, saran wrap, transistor radios, or Scooby Doo.
They and the UN are all equally relevant to the prospects for peace.
(Actually, they're all more relevant than the U.N., now that I think about it.)
You're wrong, the real reason for eliminating world wars is the tinfoil hat I have been wearing now for 42 years. Only problem is, I'm afraid to take it off in case a world war starts.