Two examples of minor Second Temple holidays that appear in Megillat Ta’anit as days on which it is forbidden to fast or to eulogize are the 13th day of Adar, which was known as Yom Nicanor, and the 12th day of Adar, which was known as Yom Turyanus. The Gemara explains the events that occurred on each of these celebratory days.
Yom Nicanor celebrated the death of Nicanor, a Greek general, who would wave his hand at Jerusalem and its environs and say, “when will this fall into my hands so that I can crush it?” When the Hasmoneans succeeded in driving the Greeks from Israel he was captured and killed.
Yom Turyanus celebrated the death of Trajan, a Roman officer who put two Jews – Pappas and Luleyanus – to death. Before doing so, he mocked them publicly, challenging the Jewish God to intervene on their behalf, as He was reputed to have done on behalf of Hananiah, Mishael and Azariah (see Daniel Chapter 3).
Luleyanus and Pappas said to him: Hananiah, Mishael, and Azariah were full-fledged righteous people, and they were worthy that a miracle should be performed for them, and Nebuchadnezzar was a legitimate king who rose to power through his merit, and it is fitting that a miracle be performed through him. But this wicked man, Trajan, is a commoner, not a real king, and it is not fitting that a miracle be performed through him…Trajan remained unmoved by their response and killed them immediately. It is said that they had not moved from the place of execution when two officials arrived from Rome with permission to remove Trajan from power, and they split his skull with clubs. This was viewed as an act of divine retribution and was established as a commemorative day.
It is interesting to note that the 13th of Adar, referred to here as Yom Nicanor, is a day that is on the Jewish calendar today as a public fast day that we know as Ta’anit Esther. Although Megillat Ta’anit has been nullified, Hanukka and Purim are still celebrated, and according to the rules of Megillat Ta’anit, the day before each of these holidays should also be celebrated; thus a public fast should be forbidden as well. The Ra’avad explains that although Purim remains a holiday, the rule forbidding fasts on the day before Purim was abolished. The Ramban points out that once Yom Nicanor was eliminated, fasting was permitted on that day, and the strength of being the day before Purim cannot be more significant than the holiday itself. Another approach suggests that Ta’anit Esther is a unique fast day, one that does not commemorate a period of mourning, but rather should be seen as part of the remembrance of the victory on Purim.