Ajatashatru

Ajatashatru overthrew his father Bimbisara, imprisoning him to seize the throne of Magadha. This act of patricide was condemned in Buddhist texts, but it secured Ajatashatru's rule and allowed him to pursue an expansionist policy.

Ajatashatru fortified the city of Rajagriha (modern Rajgir) with massive stone walls to protect Magadha's capital from attack. The fortifications included a new outer wall and strengthened defenses, making Rajagriha one of the strongest fortified cities in ancient India.

Ajatashatru sponsored the First Buddhist Council at Rajagriha, held shortly after the Buddha's death. Under the monk Mahakashyapa's leadership, 500 arhats recited and codified the Buddha's teachings (Sutras) and monastic rules (Vinaya), preserving them orally.

Ajatashatru waged a prolonged war against the Licchavi republic of Vaishali, eventually conquering it. He used new military technology including catapults and a siege engine. This victory expanded Magadha's territory and eliminated a rival power.