The occupation of the Rhineland in defiance of the Versailles and Locarno treaties was a major step forward in Hitler's plan to re-establish Germany as a respected and feared Great Power. The failure of Britain and France to threaten, much less employ, military force to prevent or reverse the occupation revealed their unwillingness to confront a revisionist, totalitarian regime that didn't hide its contempt for Western values—individualism, tolerance, and democracy. By allowing his gambit to succeed, the two most powerful European liberal democracies encouraged Hitler's megalomania and fueled his transformation into Germany's messiah. The end result was a clash of civilizations that resulted in the most destructive war in the history of the world.
(See The American Future)