Why is this day different from all other days?
Why in the world did they pick a day in Nissan, when we don’t fast or say Tachnun, to commemorate a tragedy — and in a non-Jewish manner of course?
There were Taaneisim for tragedies in past, as in the 20th of Sivan, but not for all. Perhaps the Spanish expullsion did not get a day because there was no unified Spanish community to organize it. Moreover, the survivers didn’t need any reminders that they were away from their birthplace and downtrodden, hungry, robbed and weary.
After the holocaust there wasn’t a unified She’eiris Hapleita community and people are affected by it till this day.