Kautilya's Arthashastra 13.4.60

13.4.60

śakyam ekaṃ vā sāmantaṃ sādhayet, tena dviguṇo dvitīyam, triguṇas tṛtīyam //

Or he may first put down an almost invincible immediate enemy. Having doubled his power by this victory, he may go against a second enemy; having trebled his power by this victory, he may attack a third. This is the fourth way to conquer the world.