Sadhguru
Do I need to be angry to face someone who opposes me?
A soldier needs balance, not anger
A soldier stands up for a nation, not out of personal anger or enmity with somebody. To shoot straight, a level head is needed. Krishna chose to give the Gita on the battlefield, and it speaks of equanimity, not anger.
So a soldier need not be angry. That is why Krishna chose to give the Gita on the battlefield: he is talking about equanimity, not anger.