In WWII by the order of Stalin, all (about 20,000) Polish POW officers were executed in infamous Katyn massacre.
Only one guy survived.
He was such a critic of Stalin, that Stalin ordered him tried for treason!
They pulled him right from the Katyn railroad station to stand trial in Moscow. He got like 2-3 years, and afterwards got away and testified about the massacre.
I so wish I’d understood this sooner.