The normal human perspective looks at action, events and consequences from the starting point of our own personal view and position. This is akin to trying to judge the purpose of the universe from the perspective of the earth, which, after all, is a small planet spinning around a minor sun, in a rather insignificant solar system in a tangential arm of the milky way galaxy, which is but one of an innumerable number of galaxies in the universe.
Arjuna has asked Sri Krishna to justify the horrific action he is called to carry out. He has already learned that this action is not based on his personal desire for fame, power, glory, or success, and that he should not be attached to the fruits of the action. However, he still wants to understand the deeper sense that requires this world-battle to take place and all these relatives, teachers, and leaders to be annihilated.
Sri Krishna reminds Arjuna that while he is called to be the protagonist and instrument in this action, it is not dependent on him and the required destruction will take place one way or the other, as this is the impulsion of the Time-Spirit bringing about needed change to open up the next evolutionary stage for humanity. Sri Aurobindo clarifies: “Even without thee, cries the Godhead, my will of destruction would still be accomplished….” Sri Krishna advises Arjuna further that even his immediate will to desist from the fight will not, in the end, hold out: “Nature shall yoke thee to thy work. Bound by thy own action which is born of the law of thy being, what from delusion thou desirest not to do, that thou shalt do even perforce.”
Sri Aurobindo makes it clear that nothing can occur out of sequence in the Time-Spirit’s motion: “No real peace can be till the heart of man deserves peace; the law of Vishnu cannot prevail till the debt to Rudra is paid….Teachers of the law of love and oneness there must be, for by that way must come the ultimate salvation. But not till the Time-Spirit in man is ready, can the inner and ultimate prevail over the outer and immediate reality.”
The path forward, at that time and at that place, on the “field of the dharma” (i.e. kurukshetra), required a massive destructive action. Forces that held a grip on society for self-aggrandisement and against the dictates of justice and righteousness, needed to be loosened. A new, enlightened order of society and government needed to be brought forward. Arjuna is given the command to carry out his destiny, win the battle and obtain the results that come from that victory, although not for his personal desire, but as an instrument of this Divine action.
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 10, The Vision of the World-Spirit–Time the Destroyer, pp. 369-372