Example such as? Because the big players like Europe and USA all did during WW1, then got back to the gold standard just after the war for a few years until Joh

Example such as? Because the big players like Europe and USA all did during WW1, then got back to the gold standard just after the war for a few years until John Maynard Keynes convinced everyone that it was a bad idea, and we're still debating whether that's the case to this day. I don't recall the specifics but only the USA was in a weird fiat-gold hybrid until the 70s as before that they guaranteed they would buy gold at a specific price in $