Hanukkah is known as the festival of rededication celebrates the rededication of the temple in Jerusalem after it was defiled by the Syrian Greeks all the way back in 164 BCE. It has become a beloved and joyous holiday that is celebrated yearly for a week in December for the 8-day festival.
In 167 BCE the Jews of Judea decided to revolt against King Antiochus’s oppression in the Seleucid Empire. He wanted to make sure that everyone should become Hellenized or to essentially adopt Greek Culture, but the Jews did not want this to occur. Because of this, the Syrian-Greeks desecrated the Jewish Temple and a war ensued for 3 years.
Those Jews that fought back and revolted were called the Maccabees with Judah Maccabee as their leader. Eventually, they emerged victorious from this and had an 8-day celebration thus why Hanukkah is celebrated for 8 days.
Many years later rabbis of Talmud concocted a story about the miracle of the oil. The mystery states that when the temple was desecrated all the oil was gone. But when the Maccabee’s returned they searched the temple and found only one bottle of oil that had been sealed by the high priest. It was supposed to only have enough for one day but lasted for eight days. This is what most assume is the true reason of why Hanukkah is 8 days, but this is only a legend rather than truth as there is no historical accuracy to the oil tale.
Material written around the time of the actual historical events are in the Book of Maccabees I and II. There is a letter that was sent around in 125 BCE from Hasmoneans to the leaders of Egyptian Jewry and it refers to these events as the “Festival of Sukkot celebrated in the month of Kislev (December)”. So, it turns out that Hanukkah was originally celebrated for 8 days because of Sukkot- a Jewish harvest festival that was originally 8 days ling but because of the events that occurred, they began to celebrate the rededication which in turn became Hanukkah!