ItcheSrulik, are you asking what events that weren’t related to the seige of Jerusalem do we mourn on 10 tevet? On the Chabad site I read that some remember the Holocaust on that 10 Tevet…if that’s what you’re asking.
oomis1105, that’s actually something that most secular Jews (that I know) tend to miss. They think the Holocaust was the ONLY event where Jews were killed in Europe. But it wasn’t, it was the event with the most systematic & “effecient” killing. That’s what made it so bad.
And I just recently got into an argument with an Israeli(?) because he basically said that Jews had never been persecuted in Europe before the Holocaust! I mentioned to him that he forgot the Crusades, Inquisition, & various pogroms.