सहायाभावे दुर्गमाश्रयेत यत्रामित्रः प्रभूतसैन्योऽपि भक्तयवसेन्धनोदकोपरोधं न कुर्यात्स्वयं च क्षयव्ययाभ्यां युज्येत ॥ कZ_०७.१५.०९ ॥
sahāyābhāve durgamāśrayeta yatrāmitraḥ prabhūtasainyo'pi bhaktayavasendhanodakoparodhaṃ na kuryātsvayaṃ ca kṣayavyayābhyāṃ yujyeta
In the absence of allies, one should take refuge in a fort where, even with a large army, the enemy cannot effectively blockade provisions, fodder, fuel, and water—and where the enemy is forced into attrition and expenditure (kṣaya–vyaya).
Occupy a fort that is hard to blockade for food, fodder, fuel, and water, so the besieger suffers attrition and high costs.