Death of Ōta Dōkan (1479)

Timeline

1. 1471–1478Edo Castle · EdoŌta Dōkan was originally a senior retainer of the Ōzugi-Uesugi house; in 1457 he was ordered by Uesugi Noriyoshi to build a castle at Edo, marking the origin of later Tokyo's urban development. In the 1470s he continued to serve the Uesugi, renowned as a master castle-builder, while taking part in the complex struggles among the Uesugi, the Yamanouchi-Uesugi, and the Koga kubō, holding considerable military influence across the Kanto provinces.
2. 1479Edo Castle · EdoRelations between Sadazane, son of Uesugi Noriyoshi, and Dōkan deteriorated; on July 26, 1486, Sadazane laid an ambush at Edo Castle and had Dōkan killed. According to the Record of Ōta Dōkan, Dōkan composed a deathbed verse, 'I built this castle; may those who come after preserve it,' which became a famous anecdote. The assassination further divided the Ōzugi-Uesugi house, and Edo Castle fell into Sadazane's hands.
3. 1479–1480Kanto · KantoAfter Dōkan's death, the Ōta clan split, with some members defecting to the Yamanouchi-Uesugi or other factions. The Ōzugi-Uesugi house lost its most capable military commander and fell further behind in its rivalry with Kanto shugo Uesugi Norimasa and the Yamanouchi-Uesugi. The strategic value of Edo Castle drew the ambitions of all sides, and the Sengoku transformation of Kanto was accelerated by this internal conflict.