In the Great Epic Mahabharatha , Gita was taught to Arjuna ( pandavas) by Lord Krishna in the battlefield of Kurukshethra before the commencement of War. This teaching was done by Lord Krishna to Arjuna as he was very much demoralised and ready to leave the battlefield. Because at the last minute he could not wage war with his own kith and kin, his gurus, uncles and grand fathers., brothers and their children. This chapter 1 is vividly expalined by Pujya Swami Dayanandaji.
