The two Rabbinic (i.e., no source in the five books of Moses) holidays, which we celebrate as national holidays rather than religious, are Chanukkah and Purim. These two holidays have an interesting relationship. In both instances we overcame a power which tried to destroy us. On Chanukkah we had our spiritual existance threatened by Hellenization, while on Purim it was our physical mass extinction. Chanukah celebrates the spirit of the Jews, the stubbornness of refusing to disregard our basic beliefs. Purim however is a pure and simple miracle of deliverance from the threat of destruction.
Compare the miracle of Purim to the miracle of Chanukkah.