स्वसैन्यव्यायामयोग्यं परस्यायोग्यं वर्षति यायात् ॥ कZ_०९.१.३९ ॥
sva-sainya-vyāyāma-yogyaṃ parasya ayogyaṃ varṣati yāyāt
自軍は行動に耐えうるが敵軍はそうでない雨季に、彼は進軍すべきである。
Campaign in adverse seasons only if the adverse effects are asymmetric—your preparedness converts a general constraint into a relative advantage.