Why is the story of Chanukah not mentioned in the Mishnah at all, besides for to Passing references to Halachot which apply to them in the context of Damages an the laws of planting?
In one of his sefarim (יסוד המשנה ועריכתה), R' Reuven Margalios argues that R' Yehudah Hanassi omitted mention of Chanukah from the Mishnah in order not to antagonize the Romans (since, after all, one aspect of Chanukah is the celebration of the defeat of a powerful non-Jewish occupying government).
Rabbi Michael Hasten suggests something dangerously simple: the basic observance of Chanukah is straightforward (light candles, okay), and we know from historic sources that it was wildly popular throughout the Jewish population. The Mishnah didn't concern itself with the absolute basics that everyone did and knew already. (E.g. the Mishnah opens "when is it late enough to say Shema at night?", assuming you already knew that Shema is said at night.)
Because this chag celebrating the dedication of the mizbeyach was not commonly observed after the destruction of the mikdash, along with the other days in Megillas Taanis. The gemora says this, contradicting the braisa in Shabbos that says that the opinions on the manner of lighting are from Beis Hillel and Beis Shammai. One could say that the houses preserved two obsolete traditions and argued them regardless of the fact that the days were not observed (which was common). Hanukkah was certainly observed later, it appears by the time of R. Yohanan. Ironically, around the time of the liberation of Eretz Yisrael BY THE ROMANS from the hated Palmyrene/Tadmorean occupation of the 270s.
However, the Lubavitcher Rebbe rejects this explanation for a number of reasons:
There are complimentary mentions of the Hasmoneans in various parts of the Mishnah, which serve to demonstrate that there was no resentment.
It is preposterous to suggest that Rabbi Judah the Prince would deprive the Jewish nation of vital, practical knowledge just because of an alleged family feud.
He therefore adopts an entirely different approach, which takes a look at the fundamental reasons behind the compilation of the Mishnah. You see, the same question could be asked about many other very central mitzvahs that are only minimally and obliquely discussed in the Mishnah. There’s no Tractate Tefillin, for example, or Tractate Mezuzah. Even the very first Mishnah doesn’t begin by telling you that you must say ShemaYisrael in the morning, but by asking, “What is the right time for saying the Shema?” In other words, the Mishnah presumes a certain basic knowledge and carries on from there.
There’s a good historical reason for this. Initially, it was forbidden to transcribe any part of the oral tradition. Only after the Temple was destroyed, and the Jewish infrastructure was in a precarious state, was it decided to collect the traditions and laws in an extremely concise form, so that they not be lost forever. It was only because of the pressing need that the laws, which had been transmitted orally for generations, were allowed to be committed to writing. But which laws? Only those that might otherwise be lost. Those laws and customs over which there was no such concern were to remain a purely oral tradition.
That is the reason there is only minimal discussion in the Mishnah of commonplace mitzvot such as tzitzit, tefillin or mezuzah. Everyone knew how to make them and what they needed to look like, so Rabbi Judah had neither reason nor mandate to include them in his new work.
Now, the Chanukah miracle had happened not long before the Mishnaic period, and the events as well as the observances were still fresh in the minds of the people. In addition, there were a number of works, such as Megillat Taanit and Megillat Antiochus, which contained the laws and lore of the holiday, and were available to the masses. As such, not only would including Chanukah in the Mishnah be superfluous, it would be forbidden—since the prohibition against writing down oral tradition would still apply in such a case. It was only much later, with the redaction of the Babylonian Talmud, that a wider discussion of Chanukah and its laws was included in Tractate Shabbat.
Heichal Menachem, vol. 3, pp. 221–231.
BY MENACHEM POSNER