Namaste
The Kauravas (and Karna) and the Pandavas, and their respective armies, are fighting with one another. The Mahabharata is simultaneously an exoteric account of a historical epic, and an esoteric account of internal yoga in the path to become an avadhut as achieved by Yudhisthira (the eldest of the pandavas, who is Dharma personified)
The 100 Kauravas and 5 Pandavas are cousins pitted against one another in a struggle for royal succession by a matrix of factors that trace away in many different directions. Fundamentally, the esoteric account is about how Sri Krishna, in order to eliminate all the demons and arrogant, irresponsible worldly powers from the earth before the kali yuga dawns, manipulates events on heaven and earth in order to foment a war to end the age, which officially ended with the death of Krishna's human body. It's a progressive revelation of Krishna's divinity and mission climaxing in Arjuna's chariot, when Krishna reveals himself in full.
Esotertically, the Kauravas are ignorance personified, and the 100 sons of Dhritarashtra represent the nadis (channels of subtle energy) through which one is taken away from the pure consciousness into material fixations, and subject/object dualities. This is resolved by placing the reins of one's lower mind and senses - which are like animals into the hands of god/guru,, after positioning one's vehicle in between ignorance and knowledge, seeking refuge in the guru's transmission of truth. The Pandavas (the pranas), united by the will of Draupadi, represent the single nadi by which one travels to the lotus-altar of the heart, and by performing the appropriate oblations and sacrifices, ascends the sushumna to god realization and liberation while still living.
Namaste