The Maharal answers that both reasons are true, and both are consistent with each other. The actual event for which we give thanksgiving and sing Hallel is the salvation of the Jewish people. We won a war against all odds. However, it wasn’t clear that the victory was a miracle. To people living in those times, the military success seemed to be natural. It was attributed to Jewish resilience and bravery. It didn’t appear that HASHEM had delivered us from the hands of the Yivanim; rather, it appeared as “their might, and the strength of their arms.” It was only through the miracle of the oil that they came to understand the miracle of the battle. Once people saw the oil last eight days – an overt miracle from HASHEM — they then came to see that their success on the battlefield was from HASHEM as well. The miracle of the oil revealed to them the miracle of the war.
