I'm pretty sure the sentiment that a large war has been made impossible, either through technology or politics or both, pre-dates the first World War. Certainly after the first World War, it was thought that war had thus become so horrible that it would never happen like that again.
MAD has worked pretty well so far. It seems almost certain that there would have been a massive third World War by now if nuclear weapons hadn't been invented. But that doesn't mean it can't ever happen, especially since MAD is a lot harder to work with in a multi-polar world (there are currently nine countries with nuclear weapons).
MAD has worked pretty well so far. It seems almost certain that there would have been a massive third World War by now if nuclear weapons hadn't been invented. But that doesn't mean it can't ever happen, especially since MAD is a lot harder to work with in a multi-polar world (there are currently nine countries with nuclear weapons).