Sankhaya Yog-Bhagavad Gita Chapter 2 [Contents of the Gita Summarized]
Krishna Said > Shaloka: 37
O son of Kunti, either you will be killed on the battlefield and attain the heavenly planets, or you will conquer and enjoy the earthly kingdom. Therefore get up and fight with determination.
Even though there was no certainty of victory for Arjuna’s side, he still had to fight; for, even being killed there, he could be elevated into the heavenly planets.