Answer:
Hanukkah began after the Jews defeated the Greeks in 165 BCE; it celebrates both the miraculous military victory of the small, ill-equipped Jewish army over the ruling Greek Syrians, who had banned the Jewish religion and desecrated the Temple; as well as the miracle of the small cruse of consecrated oil, which burned for eight days in the Temple's menorah instead of just one. Hope this helps!
After being destroyed and later rebuilt it was re-dedicated in 165 B.C. This began the custom.