Whenever there is unwanted population these three things will naturally, by nature’s course will appear — famine, pestilence, and war — and the population will be finished. So there was some unwanted population at that time also for which Krsna arranged the war, battlefield of war. Battlefield of war. So we have to follow. If we want very good population, very good generation, then we have to follow the principles of Bhagavad-gita.

From Srila Prabhupada’s lecture on Bhagavad-gita 3.21-25 — 30 May, 1966