Kautilya's Arthashastra 13.4.25

13.4.25

"sarvārambhopakaraṇaviṣṭisampanno 'smi, vyādhitaḥ para upadhāviruddhaprakṛtir akṛtadurgakarmanicayo vā, nirāsāraḥ sāsāro vā purā mitraiḥ saṃdhatte" ity avamardakālaḥ //

When the conqueror thinks: "I am well provided with all necessary means and with workmen whereas my enemy is diseased with officers proved to be impure under temptations, with unfinished forts and deficient stores, allied with no friends, or with friends inimical at heart," then he should consider it as an opportune moment to take up arms and storm the fort.