Shloka 43
Daṇḍanīti and the King as the Cause of Yuga-Order (दण्डनीतिः राजधर्मश्च युगकारणत्वम्)
प्रगण्डी: कारयेत् सम्यगाकाशजननीस्तदा । आपूरयेच्च परिखां स्थाणुनक्रझषाकुलाम्
pragaṇḍīḥ kārayet samyag ākāśa-jananīs tadā | āpūrayec ca parikhāṃ sthāṇu-nakra-jhaṣākulām ||
毗湿摩说：“随后当妥善营建普罗甘底（pragaṇḍī，防御平台与工事），并在适当处设置阿迦舍阇那尼（ākāśa-jananī）——墙上供窥察与发射兵器的细小孔隙。又当使城垣外壕沟注满水，于其中立置如尖桩般、装有三叉戟的木柱，并放养鳄鱼与巨鱼。如此布置城堡，方可安置警觉的勇士守护，并遏止敌军逼近。”
भीष्म उवाच
Educational Q&A
In rājadharma, protection of subjects is a primary duty; Bhīṣma teaches that a ruler should ensure layered, well-planned defenses—platforms for guards, controlled openings for observation and missile use, and moats with obstacles—so that security is maintained and aggression is deterred.
Bhīṣma is instructing on practical fort-defense: build pragaṇḍīs and ākāśa-jananī openings correctly, then strengthen the outer perimeter by filling the moat with water and adding dangerous impediments like spiked posts, crocodiles, and large fish.