I'm gonna drop my comment here. Despite Schlieffen Plan was brilliant, it was a completely disastrous diplomatical mistake. The western powers were war weary and had strong disputes in internal affairs. France is one of them. They had a big commie support, if they manage to take power hitler's crusade against communism (which I strongly assume that was the reason why western powers let hitler run amok until molotov-ribbentrop pact) would be legitimate in the eyes of west. With western border is already secure also supported in a degree he would have better chance against SU.

But he COMPLETELY misread the situation. Though I think after signign molotov-ribbentrop he completely lost the western support, he could not repent after that.