Chanuka - what was the real miracle?

Was the miracle the fact that they found the oil? Was it that the oil lasted all 8 days? Was it that they won the war over the mighty greeks?

From the fact that we light menorah, it seems that the miracle is that the oil lasted all 8 days. The gemara in meseches shabbos asks "mai chanuka?" (What is the reason that we celebrate chanuka). The answer seems to talk only about the miracle of finding the oil and about it lasting all the nights.

Al hanisim on the other hand describes the war and that fact that we won over the Hellenists and we were saved etc?

Which one is it? Why does al hanisim not really put emphasis on the miracle of the oil?