Kautilya's Arthashastra 9.1.44

9.1.44

yadā vā prayātaḥ karśayitum ucchetuṃ vā śaknuyād amitraṃ tadā yāyāt //

But Kautilya says: that when one's resources are sufficient one should march, since the troubles of an enemy cannot be properly recognised; or whenever one finds it possible to reduce or destroy an enemy by marching against him, then one may undertake a march.