Kautilya's Arthashastra 13.4.8

13.4.8

"prabhūtaguṇabaddha(vaddha).anyakupyayantraśastrāvaraṇaviṣṭir aśmisamagraṃ me sainyam, ṛtuś ca purastāt, apartuḥ parasya, vyādhidurbhikṣanicayarakṣākṣayaḥ krītabalanirvedo mitrabalanirvedaś ca" iti paryupāsīta //

When the conqueror thinks: "My army is provided with abundance of staple corn, raw materials, machines, weapons, dress, labourers, ropes and the like, and has a favourable season to act, whereas my enemy has an unfavourable season and is suffering from disease, famine and loss of stores and defencive force, while his hired troops as well as the army of his friend are in a miserable condition,"--then he may begin the siege.