Above: A menorah on a Hasmonean coin
Hanukkah was originally called "Orot" ("Lights") and celebrated and commemmorated the resuption of Temple sacrifices after the Hasmoneans (Maccabees) captured the Temple from the Greeks and Hellenizing Jews, Josephus – a kohen who served in the Temple about 200 years after the Hasmonean revolt – wrote:
Now Judas celebrated the festival of the restoration of the sacrifices of the temple for eight days, and omitted no sort of pleasures thereon; but he feasted them upon very rich and splendid sacrifices; and he honored God, and delighted them by hymns and psalms. Nay, they were so very glad at the revival of their customs, when, after a long time of intermission, they unexpectedly had regained the freedom of their worship, that they made it a law for their posterity, that they should keep a festival, on account of the restoration of their temple worship, for eight days. And from that time to this we celebrate this festival, and call it Lights. I suppose the reason was, because this liberty beyond our hopes appeared to us; and that thence was the name given to that festival.– Josephus, Antiquities of the Jews, 12.7.7 Whitson translation.
You'll note there is no mention of the purported miracle of oil. That's because the rabbis made it up hundreds of years later.
[Hat Tip: Yochanan Lavie.]