Kautilya's Arthashastra 7.10.37

7.10.37

khanakā hi khātena śastreṇa cobhayathā yudhyante, śastreṇaivākāśayodhinaḥ //

Of the two enemies, one fighting from ditches and another from heights (khanakákásayodhibhyám), seizing land from the former is better; for they can be serviceable inasmuch as they fight from ditches and with weapons in hand, whereas the latter can only fight with weapons in hand.