What if the French and British had stepped up their actions against Germany during the German invasion of Poland?
There are three scenarios that I've been wondering about.
1: Britain and France commit troops to Poland itself to help hold off the German invasion, as soon as possible after the invasion begins.
2: A larger Saar offensive, in which the French military succeeds in launching its 40-division assault and isn't quite so half-hearted.
3: A combination of both.
What would happen in any of these situations?