The Greeks began by banning three mitzvos in their attempts to secularise Judaism; Rosh Chodesh, Shabbos, and circumcision. Each is central to Jewish identity. Existence consists of a fusion of time, space, and consciousness.
Rosh Chodesh addresses time, and a Jew’s obligation to master it. Shabbos testifies to Hashem’s mastery of the universe, and a Jew’s obedience to His will. Circumcision is targeted at the soul, and a Jew’s entire way of life.
Without these three, Jewish identity in existence was lost, and ultimately doomed. The resistance out an end to that.
And as the Sfas Emes and Maharal observe, Chanuka references all these three; Chanuka is eight days long, when the mitzva of Mila begins. There is always a Shabbos in the middle of Chanuka, and a Rosh Chodesh too!