Genpei War: In the Battle of Ishibashiyama in Japan, the new military commander of the Minamoto clan, Minamoto no Yoritomo, is routed by Ōba Kagechika of the Taira clan.

The Genpei War was a national civil war between the Taira and Minamoto clans during the late Heian period of Japan. It resulted in the downfall of the Taira and the establishment of the Kamakura shogunate under Minamoto no Yoritomo, who appointed himself as Shōgun in 1192, governing Japan as a military dictator from the eastern city of Kamakura.

The Battle of Ishibashiyama was the first in which Minamoto no Yoritomo, who became shōgun less than a decade later, was commander of the Minamoto forces. The battle was fought on September 14, 1180, in the southwest of present-day Odawara, Kanagawa Prefecture, near Yoritomo's headquarters at Kamakura.

Minamoto was a noble surname bestowed by the Emperors of Japan upon members of the imperial family who were excluded from the line of succession and demoted into the ranks of the nobility since 814. Several noble lines were bestowed the surname, the most notable of which was the Seiwa Genji, whose descendants established the Kamakura and Ashikaga shogunates following the Heian era. The Minamoto was one of the four great clans that dominated Japanese politics during the Heian period in Japanese history—the other three were the Fujiwara, the Taira, and the Tachibana.

Minamoto no Yoritomo was the founder and the first shogun of the Kamakura shogunate, ruling from 1192 until 1199, also the first ruling shogun in the history of Japan. He was married to Hōjō Masako, who acted as regent (shikken) after his death.