you can only blame the geopolitical genius of hitler.  why ally yourself with poland to attack the soviets together from a far further front line, when you can attack them for the sake of 350 000 germans, while burning all diplomatic bridges and giving the uk a perfect reason to declare war, while hoping they just won't stick to their word and let hitler take whatever he wants.  i'm not blue-pilled on the issue, but if you approach it as honestly as you can, you have to acknowledge, that adolf's geopolitical moves were an absolute disaster.
Poland