Gempei War, (1180–85), final struggle in Japan between the Taira and Minamoto clans that resulted in the Minamoto’s establishment of the Kamakura shogunate, a military dictatorship that dominated Japan from 1192 to 1333.
The Taira clan had dominated the Imperial government from 1160 to 1185. Minamoto Yoritomo, the son of the great Minamoto leader Yoshitomo, had been spared after his father’s defeat in 1160 because of his youth. Now an adult, he capitalized on the growing dissent with Taira leadership on behalf of members of both the Taira and Minamoto families and organized a new revolt in 1180. He soon gained control of the strategic east coast of Japan and by 1182 was ready to advance on the capital at Kyōto. The Taira leaders fled, taking with them the infant emperor Antoku. In the sea battle of Dannoura (1185) on the Inland Sea in western Japan, the Taira were finally defeated. The emperor Antoku was drowned in the battle, losing a famous sword, one of the Imperial Treasures of Japan supposedly brought from heaven by the first Japanese emperor. The battle became legendary through accounts such as the Gempei seisui-ki (“Record of the Rise and Fall of the Minamoto and Taira”).