In Megilas Esther 2:16 it mentions that Esther was taken in Teveis to Achasverosh's palace. Does anyone know on which day of the month this happened?
According to an online sources, it was on 1 Tevet.
I'd have to look in the Mefarshim to see if they say which date it was on.
The רמ"א reportedly says it was the 9th of טבת.
It is not the רמ"א on או"ח סימן תקפ, although it is ostensibly the event commemorated by the fast on the ninth of טבת. I have heard this by rumor only so far and will try to find a link inside.