Yoritomo’s Ōshū Campaign and the Fall of the Northern Fujiwara

In 1189, Fujiwara no Yasuhira killed Yoshitsune, whom the Northern Fujiwara had sheltered at Hiraizumi. Sending his head to Yoritomo did not prevent a further campaign. Yoritomo pressed the court over the northern government’s handling of the fugitive and mobilized his followers for an invasion. The campaign would bring an established regional center and its lands under Kamakura’s military authority.

Forces advanced along several approaches, with Yoritomo’s main column moving north through Shirakawa. The defenders tried to block it around Atsukashiyama in southern Mutsu. Ditches and earthworks connected the slopes with the river landscape; excavated sections include paired ditches cut into bedrock. Fujiwara no Kunihira’s defense collapsed after heavy fighting, opening the northern route.

Yasuhira fled before Yoritomo entered Hiraizumi. The Northern Fujiwara government ended. Land was redistributed to Kamakura followers, alongside some continuing older landholders.

The settlement placed new warrior interests in the northeast but also retained some older landholding families. The surviving defensive earthworks and Hiraizumi’s religious sites preserve different parts of this change: the attempt to resist invasion and the institutions that continued after the regional government fell.