> It was more complicated than that: the Polish government in exile knew at least as early as 1940 and by at least 1942 those had been corroborated by allies and there were official reports presented to allied governments, the UN, and covered in major newspapers:

I had no idea that the "United Nations" was a thing during WWII (though it appears to be more of a synonym for the allies than the body we're familiar with today).