Officially, the Red Army ordered that rapists be shot on sight.
Of course, they didn’t exactly enforce that order, but the fact that the order was issued in the first place showed that mass rape wasn’t considered “acceptable” to the general population.
The concept of bloodied, angry, and possibly-grieving soldiers who’ve just fought through the butchery of an avoidable battle (the laws and customs of war allowed a city one last chance to surrender before a besieging force tries to take it by storm) which the defenders only forced them to fight through pure spite is one that does warrant examination, and it’s one that I’ve examined. Yet there are aspects of it which I’d only want to be able to touch upon peripherally, because it’s one thing to describe the mindset of a soldier during a sack, but it’s another to try to put the reader in that mindset, while still keeping both author and reader’s grasp of their own human decency.