The gemara in Shabbos tells us that the reason the festival of Chanukah was fixed as a permanent festival was because of the miracle of the single flask of oil lasting 8 days. Rav Chaim Shmuelevitz zt"l points out that the miracles that enabled the Hasmoneans to overcome the mighty Greek army seem to have been of far more importance than the miracle of the oil. The military victory facilitated the removal of Greek hegemony and the freedom to observe the Torah. The miracle of the oil played no part in this victory, rather it enabled the Menorah to be lit for an extra seven days. Rav Shmuelevitz asks that it would have seemed more understandable to establish the festival of Chanukah because of the military victory rather than that of the oil.
He explains that there are two reasons why Hashem may perform a miracle. One is when there is an absolute necessity for the miracle to take place. For example, the miracle of the manna in the desert was of the utmost necessity in enabling the people to eat whilst living in the desert. However, there are other miracles that are not particularly essential, rather their main function is to show Hashem's particular love for the recipient of the miracle. He proceeds to give a number of examples of such miracles in Tanach.
He cites the incident in which David Hamelech slew Goliath. The Prophet tells us that when Goliath was struck by the stone, he should have fallen backwards, but he unnaturally fell forward. Rashi, quoting a Medrash, explains that Hashem caused a 'miracle' that Goliath would fall forward so as to save David having to walk an extra few meters to cut off Goliath's head. This is clearly a miracle that was not of the utmost necessity, however Hashem performed it to show His love for David.
The Ohr HaChaim points out another, remarkable example of a miracle of 'love'. In Parshas Lech Lecha, Hashem instructs Avraham: "Please raise your eyes and see from the place where you are standing, north, south, east and west." Hashem was showing Avraham the land of Israel and promising him that his descendants would own this land for eternity. The Ohr HaChaim notes the seemingly superfluous words, "from where you are standing" - what is this ostensibly obvious phrase coming to add? He explains that Hashem made a tremendous miracle whereby Avraham could see the whole of the land of Israel from all directions from the exact place that he was standing, without even having to turn his body!
Rav Shmuelevitz observes that both of these miracles were of minor importance. Their main significance was as expressions of Hashem's infinite love for those who served Him with such dedication. Indeed, the lesser the necessity of the miracle, the greater the show of love it expressed. He gives an analogy to help further understand this idea. A family loses a very expensive diamond, which was an inheritance from many generations earlier. All the family feels great pain at this loss and search extensively to find the diamond. Eventually, one of the children finds the diamond. In his great joy, his father kisses his son on his head. All the family feel great at finding the diamond, but the boy has the extra joy of the kiss from his father.
In this vein, we can now understand the significance of the miracle of the oil. Of course the miracles of the military victory were essential and the miracle of the oil was of far lesser necessity. However, because of this, it represented a far greater show of love from Hashem. It was an extra show of affection that demonstrated Hashem's love for the Hasmoneans.
The question remains, of why, at this particular instance, did Hashem choose to alter nature for the miracle of the oil? It is clear from the above examples that Hashem only performs 'unnecessary' miracles for people of great righteousness such as Avraham Avinu and David HaMelech. Why did the Hasmoneans merit to experience such a miracle?
It seems that Hashem performed this 'extra' act of love, measure for measure for the actions of the Hasmonean when they returned to the Beis HaMikdosh and found only one flask of pure oil. The commentaries explain that it was technically permissible to have used the impure oil in this situation. Yet they chose to be mehader and perform the mitzvo in the most optimal fashion as a sign of their great love for Hashem. Because they were willing to go beyond the letter of the law, in reward, Hashem also went 'beyond the letter of the law' so-to-speak, and performed a non-vital miracle as a sign of His love for them. This also explains the unique feature of the mitzvo of lighting the Menorah - the concepts of Mehadrin and Mehadrin Min haMehadrin. It is a universal custom that everyone strives to perform the mitzvo to its most optimal fashion, despite the fact that the basic mitzvo is only one candle per person per day. We perform the mitzvo with the maximum hidur both as a remembrance of the Hasmonean's hidurim, and of Hashem's hidur of performing the miracle of the oil.
We have learnt that the uniqueness of the miracle of the oil is the mutual show of love between Hashem and the Jewish people. We learn two vital lessons from here. Firstly, we should remember the great love that Hashem showed for His people, and realize that He has the same love for every Jew. Secondly, we learn that we should strive to emulate the Hasmonean's willingness to perform mitzvos in the optimum fashion as a manifestation of our love for Hashem. May we all merit to apply the lessons of Chanakah to our lives.