Chanuka is said to be the ‘festival’ of the Oral Torah, so why is there no Gemora about Chanuka? We have by Purim, Pesach, Succos, but why not by Chanuka?
Rav Nissan Kaplan shlit”a suggests a beautiful answer:
The Greeks did not try to destroy us physically, they tried to destroy our Torah – our identity. So, when it was time for Rebbe to write down the Mishnayos due to fear that the Jewish People would start to forget the Oral Torah, to some extent, the Greeks had succeeded. They had taken our Oral Torah and to a degree, reduced it. So, when it came to Chanuka, the time when we celebrate our success over the Greeks and their values, Rebbe could not let Chanuka be written down into Mishnayos, Chanuka had to remain as the Oral Torah in its unchanged form. So even though the Greeks succeeded in a way, by causing our Oral Torah to be written down, at least when it came to Chanuka, the ‘festival of the Oral Torah’, that would have to be learned totally orally without any Mishnayos.