Understand

Can you do violence and not be morally stained?

The hardest reading problem in the text: a battlefield sermon that says fight.

One reading

Acting without ego or craving, from duty rather than hatred, leaves no residue — 'he slays not, nor is bound'.

BG 18.17 — He who is free from the egoistic notion, whose Reason is not affected, though he slay these peoples, he slayeth not, nor is bound. read →
BG 4.21 — Hoping for naught, his mind and self controlled, having abandoned all greed, performing action by the body alone, he doth not commit sin. read →
BG 2.38 — Taking as equal pleasure and pain, gain and loss, victory and defeat, gird thee for the battle; thus thou shalt not incur sin. read →

The tension

The Gita elsewhere makes non-harm a core virtue, listed among the marks of the divine nature.

BG 16.2 — Harmlessness, truth, absence of wrath, renunciation, peacefulness, absence of crookedness, compassion to living beings, uncovetousness, mildness, modesty, absence of fickleness, read →
BG 13.8 — Humility, unpretentiousness, harmlessness, forgiveness, rectitude, service of the teacher, purity, steadfastness, self-control. read →
BG 10.5 — Harmlessness, equanimity, content, austerity, almsgiving, fame and obloquy are the various characteristics of beings issuing from Me. read →

My reading

This is where the Gita is most demanding and most contested. Its claim is that intention and attachment are what bind (18.17), so a just war fought without cruelty or gain differs in kind from violence for its own ends. Whether that distinction holds under real pressure is a fair question to keep open — the text asserts it; it does not prove it.