The war fought by the Hasmoneans against the Greeks raises a complex halakhic (Jewish legal) question. They were few and weak, while the Greeks were numerous and strong. From a purely probabilities standpoint, the Hasmoneans had no natural chance of winning. How could they have been allowed to fight such a war, where the lives of every soldier were in certain danger? We could answer that it was a life-or-death situation. The Greeks attempted to eradicate Judaism, to uproot the Torah and the mitzvot from the Jewish people. In such a situation, one must sacrifice oneself and not transgress even those mitzvot that, in another situation, one might overlook to save one's life.
However, this answer does not address the question. A "life or death" situation means that a Jew is forced to transgress any mitzvah, in which case the Torah requires one to die rather than transgress. But even in a "life or death" situation, there is no obligation to go to war against the government, and especially not a war that is lost from the outset according to the laws of nature!.
Here we see the greatness of the Hasmoneans, who acted imbued with boundless self-sacrifice. There is such a thing as limited and measured sacrifice. While one is ready to give one's life, there is a limit and a measure to sacrifice; there are things for which one will sacrifice, and things for which one will not. The Hasmoneans were filled with boundless sacrifice, and so, from their perspective, there was no room for questioning.
This concept is indicated in the liturgy of "Hanerot Halalu" (the liturgy sung after the lighting of the Hanukkah candles), where it is emphasized that the miracles God performed came through "Your holy Kohanim (priests)." Maimonides, in his book of laws, is also precise, writing: "The Hasmoneans, the High Priests, triumphed and killed the Greeks and saved Israel from their hands." Why is it important to emphasize that the miracles came through "Your holy Kohanim" and the "Hasmoneans, the High Priests"?.
For here lies the source of the halakhic permission to go to war like this, which has no chance of victory. Halakha states that there are certain transgressions for which a person is forbidden to sacrifice their life. However, "If a person is wise, pious, and God-fearing, and sees that the generation is not paying attention to the mitzvot, it is permissible to sanctify God's name and sacrifice their life even for a simple mitzvah." The Hasmoneans were among these "wise and pious" individuals, permitted to sacrifice their lives without limits or restraint, even beyond the limits of the Torah.
Since the Hasmoneans rose to a spiritual level of boundless sacrifice, they were worthy of miracles that transcended the limits of nature. First and foremost, there were the miracles of victory in war, where the few and weak overcame the many and strong, including the miracle of the jar of oil.
The jar of pure oil, sealed with the High Priest's seal, symbolizes absolute surrender to God, even to the point of limitless and immeasurable self-sacrifice. The Hasmoneans rose to this spiritual level and thus had the strength to defeat the Greeks and bring salvation to the Jewish people.
Extracted from Likutei Sijot vol. 35 page 169