That’s right; Stalin didn’t want an independent pro-Western government in power when the Soviets reached Warsaw (that is why the Soviets executed Polish officers and such in the first invasion), so they let the Germans crush them first.
In the end, Britain and France went to war for Poland’s independence and ended up without it; Churchill was furious. All those lives wasted for nothing, and they both ended up with very weakened empires.
One of the other things the Soviets did, was to provoke tensions between Christians and Jews in Poland, to divide-and-conquer.
“In the end, Britain and France went to war for Poland’s independence and ended up without it; Churchill was furious.”
Churchill and Roosevelt got played by Communists in their own administration who were directing all their efforts toward helping Stalin and his regime gain as large a foothold in the West as possible.