Why do the traditional sources seem to downplay the military aspect of Chanuka and focus more on the theme of oil and light?
Clearly, one of the main reasons for establishing Chanuka as a festival for all Jews in all generations was to commemorate the miraculous military victory of the Maccabees over the Greeks. In fact, the special additions to be recited in the prayers and the blessing after meals during Chanuka make explicit mention of the military aspect of the victory: “You delivered the strong into the hands of the weak, the many into the hands of the few…”.
However, the continuation of the same prayer states: “[You delivered] the impure into the hands of the pure, the wicked into the hands of the righteous, and the wanton into the hands of those dedicated to Your Torah”. The fact that the prayer enumerates more, and crescendos with, matters of spiritual victory does indicate as you suggest that the main emphasis is on the miracle of the oil, menora and light. Why?
While initially the military victory resulted in both the physical and spiritual independence of the Jewish people such that their enemies were defeated and the decrees against Torah observance were nullified, eventually the Hasmonean dynasty declined, the Temple was destroyed and the Jews became subjugated again to the nations. Therefore, what was primarily left of the Chanuka miracle for the Jews to celebrate was the spiritual victory which continued to kindle light into the darkness of exile.
The light of the Menora represents the illumination of the Torah in the hearts and minds of the Jewish People. The Greeks entering the Temple and defiling the oil corresponded with the penetration of Greek culture into Israel which blemished their hearts and minds with the impure notion that the “wisdom of the Greeks” surpassed that of the Torah, G‑d forbid.
When the Hasmoneans regained the Temple and found even just a small quantity of oil untouched and undefiled by the Greeks, this symbolized the fact that despite all the Greeks had done to contaminate the hearts and minds of the Jews, there still remained a source of potential purity which could be sparked to rekindle the unique Jewish role as a Light unto the nations.
However, this “oil” seemed barely enough to last for those days alone. Where would Israel find enough to burn through the completion of the world as we know it into Messianic times? [This concept is symbolized by the eight days of the festival, because seven represents the natural cycle of time whereas eight symbolizes things that transcend time.] G‑d came to their assistance in this darkest hour to ignite the spark of true Torah wisdom in the hearts and minds of the Jews which He fanned into a flame that illuminates their path through exile till redemption.
This miracle of purifying the heart and mind with the oil of Torah is necessary for Israel in every generation – especially when Israel is subjugated and threatened by the nations of the world. As long as Jews’ faith and wisdom is purely Jewish, it is through this light that they will find liberation. But when the Jewish People’s faith and wisdom become defiled by the impurity of beliefs and practices antithetical to the Torah, they perpetuate their own subjugation.
Therefore, it is through the unique illumination of Torah that the sanctity and unique identity of Israel among the nations is preserved. This dynamic is a miracle which endures through the generations and can find its expression in every age. Yet not every generation is worthy of complete and enduring military victory. It is for this reason, then, that the commemoration of the Chanuka miracle relates primarily to the vigilant rekindling of the Menora whose illuminating message shines through all generations till the Day of Redemption.