Krishna was Arjuna’s charioteer during the Kurukshetra War in the Mahabharata.
Before the war, Krishna offers Arjuna and Duryodhana a choice: one may have Krishna’s army, while the other may have Krishna himself, who will not fight. Duryodhana chooses the army, and Arjuna chooses Krishna. Krishna then serves as Arjuna’s charioteer and guide.
On the battlefield, Arjuna becomes overwhelmed by the prospect of fighting relatives, teachers, and friends. Krishna answers his crisis in the Bhagavad Gita, explaining duty, disciplined action, devotion, knowledge, and the nature of the self.
Krishna’s role is therefore more than practical transportation. He is simultaneously Arjuna’s friend, counselor, divine teacher, and, in the Gita, the supreme spiritual reality revealed through his universal form.