The setting is fixed and static: the armies are drawn up, Arjuna asks to be driven between them, and the entire text happens before a single arrow is loosed. It reaches the reader at two removes, Sanjaya, granted distant sight, is narrating the battlefield to the blind king Dhritarashtra, so every word of Krishna arrives as reported speech.
Arjuna's objection is not cowardice but a moral one. Killing teachers and kinsmen will destroy the family, and with it the order that families sustain. Krishna's reply moves through several registers rather than one argument. The self is not born and does not die, so what Arjuna thinks he is destroying is not what he thinks. Withdrawal is impossible anyway, since to be embodied is to act. What can be changed is the relation to action: nishkama karma, acting without appetite for the result, which turns work into something that does not bind. And there is svadharma, one's own duty by station, better done badly than another's done well, which is the text's most quoted and most contested move, since Arjuna's own duty is the warrior's.
Broadly, the first six chapters concentrate on disciplined action, the middle six on bhakti, loving devotion to a personal God, and the last six on knowledge, the three gunas, and the analysis of the self. The pivot is chapter eleven, where Krishna grants Arjuna a divine eye and shows the universal form, all worlds and all beings at once, the enemy already dying inside its mouths, and Arjuna, terrified, asks for the familiar shape back. The chapter supplied Robert Oppenheimer his line about becoming death.
The close is not philosophy but instruction: surrender, and be freed. Whether that supersedes the earlier paths or completes them is the question every commentator has to answer.