Menorahs and Mezuzahs

The Al HaNissim we add to davening speaks almost entirely about the victory over the Greeks. Yet when the Gemara asks "What is Chanukah?", it answers with the oil. Which miracle is the real one, and why do the two sources seem to disagree? The answer starts with what makes any miracle significant. Then comes a small halacha that raised a second question: why is the menorah placed opposite the mezuzah, so that we stand surrounded by mitzvos? One idea about what the Greeks wanted answers both.