Kautilya's Arthashastra 2.33.8

2.33.8

sa maulabhṛtaśreṇimitrāmitrāṭavībalānāṃ sāraphalgutāṃ vidyāt, nimnasthalaprakāśakūṭakhanakākāśadivārātri.yuddhavyāyāmaṃ ca, āyogam ayogaṃ ca karmasu //

The latter shall know the exact strength or weakness of hereditary troops (maula), hired troops (bhrita), the corporate body of troops (sreni), as well as that of the army of friendly or unfriendly kings and of wild tribes.

He shall be thoroughly familiar with the nature of fighting in low grounds, of open battle, of fraudulent attack, of fighting under the cover of entrenchment (khanakayuddha), or from heights (ákásayuddha), and of fighting during the day and night, besides the drill necessary for such warfare.

He shall also know the fitness or unfitness of troops on emergent occasions.