तुल्यदुर्गाणां निचयापसारतो विशेषः ॥ कZ_०७.१५.१० ॥
tulyadurgāṇāṃ nicayāpasārato viśeṣaḥ
Among forts of equal strength, the decisive difference lies in (i) capacity to stockpile and (ii) capacity to withdraw/evacuate (apasāra).
By their ability to accumulate supplies and to execute an orderly withdrawal/evacuation when needed.