An "Early" Taanit Esther

When a fast day occurs on Shabbat (e.g. Tisha B’Av or the 17th of Tammuz) we delay its observance until the following day, Sunday. The reason for this is explained in the Talmud so as not to hasten the reminder of a tragedy ["akdumei puranuta lo makdaminan" – Megilla 5a]

However, when Ta'anit Esther – the 13th of Adar - falls on Shabbat, it is observed on the previous Thursday. The simplest explanation for this is because Taanit Esther does not recall a tragedy, but rather the fast that the Jews observed on the day of their battle with Haman’s loyalists [Chidushei HaRan Taanit Chapter 2]. However, HaRav Yosef Dov Soloveitchik, zt"l suggested an additional reason - that Taanit Esther is part of the “pirsumei nisa” experience [publicizing the miracle of G-d’s salvation] that is so integral to Purim. Specifically, by observing before celebrating the victory of Purim, we preserve the historic nature of the season - that G-d responded to our pleas and fasting.

This may also be an additional reason why Taanit Esther is the most lenient of all fasts [Orach Chayim siman 686] - since unlike all the other fasts, Taanit Esther is the only fast which is part of a celebration and not an observance of national tragedy!

Finally, when Taanit Esther is moved from its regular date, it is even more lenient than in most years. As a result, even according to those who may be stringent about a regularly scheduled Taanit Esther [i.e. Rambam] in a year when Taanit Esther is “early” a person who has even a minor problem fasting can break this fast.