So, there's odds and ends of 'their world is our world' about Harry Potter. Quite a lot about the series suggest that wizards are in our world, in secret. Of course, non-magical folks wouldn't notice anything, right? Because they're a secret...
So here's the thing, great seismic events in history would have happened the same way, presumably. So did, for instance, the second world war happen in the world of Harry Potter.
And if so, why didn't the wizards do anything about it?