I notice you already have this question for the Holocaust but haven't found it for the Spanish expulsion. I understand that many great people gave reasons for it, like the seder hadoros, tsror hamor ...
The Sha'ar haTziyun (OC 550 sk 9) speculates if in his day (~1900 CE) there was enough oppression of the Jews to warrant declaring the fasts of 10 Tevet, 17 Tammuz and 3 Tishrei into full fledged ...
I don't know if this is off topic but a similar question is here at Christianity SE and I thought it would be interesting to ask the corresponding one here. It intrigues me how people from other ...