I know a decent amount about it, but I realized I don’t have sources for it and I want to convince a Castroist comrade that they’re not as bad as liberal propaganda says.

I’m aware that the bulk of the officers who were purged were reactionaries and opportunists, and I’m aware that though some of them were killed during the purges, a lot of them were simply given a prison sentence. Further, I know that some of them proved that they weren’t untrustworthy and returned to the red army, and that many of the officers arrested during the purge were released post-war. But, I don’t have sources for that, and searching for sources can be a soul-sucking experience.