Versailles Treaty should've been much harsher than it already was , if France wanted to neutralize Germany as a threat. You either utterly destroy Germany and ensure that it won't get back up or make the original treaty not as bad.
Or they go "Vae vicits!" and the French, or whomever, is allowed to get seriously punitive with Germany. And that would likely have been pretty horrific. It's only that hindsight tells us whatever it would have been, for it to top Nazi Germany and WWII it would have had quite some ground of nasty to cover.