Is such a scenario plausible? As far as I know Hitler was (correctly) convinced that France and Britain wouldn’t do much to help Poland; apparently he wasn’t even certain that they would declare war at all.
But what if he was convinced that the Entente would launch a full scale invasion of Germany within weeks of a German attack on Poland? I mean, was there any reason in particular why he wouldn’t expect something like this, instead of the anemic and half-hearted reaction from the western powers we saw OTL?
If he feared the French and British military reaction enough, might he prefer to preemptively invade France (and the Low Countries), while taking a defensive position against Poland? Basically, take out the bigger danger in the west before dealing with the Poles? Germany would still declare war on Poland, but wouldn’t do much beyond border skirmishes, and instead strike west as soon as the French and British DoWs arrive.
Would Poland try to invade Germany in that case? The M-R pact already happened, so they would rightfully fear a possible Soviet attack from the east if they get bogged down in Germany. Could we see a ‘Phoney War’ between Germany and Poland, while the real action happens in the west? Alternatively, if Hitler invades France first, would Stalin attack Poland from the east while the other powers are distracted? Hitler might even count on it, to keep the Poles busy. How would a Soviet invasion of Poland go if the Poles aren’t being invaded by Germany at the same time?
Is there any particular reason why Hitler had to invade Poland first? I guess the captured Polish equipment was helpful, and by September 1939 the Germans would’ve had less time to produce tanks and planes compared to May 1940 (though the same would be true for France and Britain). On the other hand, if the Germans had invaded France within days after the French DoW, wouldn’t that mean the invasion takes place before the French (and British) are even properly mobilized?
Let’s imagine France and the Low Countries had fallen in September/October 1939, while the Soviets are slowly but surely moving deeper into Poland from the east (I doubt we would see a successful Soviet ‘Blitzkrieg’ in 1939). With France taken out of the picture (and lots of captured French equipment), Hitler invades Poland from the west in November or December 1939, with a similar end result as OTL.
Basically, the situation by the end of 1939 would look like the OTL situation of summer 1940. What effects would such an early defeat of France have on the course of the war? The situation the Soviets find themselves in might be a bit more uncomfortable than OTL: since they kept the Poles busy during the German invasion of the west, they might be regarded as co-belligerents of the Germans even more than OTL. This is especially especially true if Stalin still attacks Finland and occupies the Baltic countries, since this would take place after most of the action on the continent is already over, which means most of the world’s attention would be on the Soviets (unlike OTL, where this happened while Germany was still fighting the British and French in western Europe).
Or is the whole idea completely ASB, and taking out Poland first was the only option?