Personal anecdote, but I’ve spoken to a few Polish survivors because Australia accepted many as refugees – Anyway, the stories they told me of being oppressed by both Germans and Russians were quite detailed and horrific. One of them, who was a militiaman, said that, surprisingly, the Germans treated the Poles better. He talked about how if soldiers or the police found you, then you’d best hope it’s a German instead of a Russian. He talked about the horror of discovering that the forces in the North weren’t German, they were Russian, and they weren’t there to fight for the Poles.

He managed to flee after British forces bombed one of the railways, and he was on the train with a bunch of other labourers. The guards all ran because there was fighting or something going on, giving some boxcars a chance to escape, which was later discovered by the Americans. The Americans opened fire on them, and after a few hours came to realise they were civilians and brought them into the UK.

I found that fascinating, 96 years old

https://en.wikipedia.org/wiki/Katyn_massacre

https://en.wikipedia.org/wiki/Soviet_repressions_of_Polish_citizens_(1939–1946)

https://en.wikipedia.org/wiki/Polish_Operation_of_the_NKVD