Dear Rabbi Kornfeld:
The Gemara in Shabbos 21b says that after the Chashmonaim were victorious over the Syrian-Greeks and wished to light the Menorah in the Beis Hamikdash, they only found one container of oil with the seal of the Kohen Gadol which would provide light for only one day. Miraculously, this remained lit for eight days. The Gemara says that ''the following year they (presumably Chazal) established festival of Chanuka for giving hallel v'hodaah'' i.e. to the Ribono shel Olam for the miracles of that time. Is there any significance to the fact that the Gemara tells us that the festival was put into effect the very next year?
According to the MINCHAS BARUCH (#104:3), the intent of Chazal is to show that there was also an eight day celebration during the first year, before the miracle of the oil occurred. That holiday served as the model upon which our eight day holiday (because of the miracle of the oil) was based.
He explains (based firmly in the teachings of Megilas Ta'anis) that Chazal original planned an eight day celebration during the time that they were re-dedicating the Temple, patterned after the seven-day holidays that Shlomo and Ezra made (see Moed Katan 9). (They added an eighth day to celebrate the victory.) They did not expect a miracle, nor did they expect to make a similar celebration the following year.
After the oil burned for eight days, they took the miracle as on omen from Above, and instituted a yearly eight day holiday, beginning the following year, to commemorate the miracle of the oil. This is the holiday we celebrate.
With this premise he answers the numerous contradictions in Chazal whether the eight day holiday commemorates the victory and rededication of the Temple or the miracle of the oil.