A retired emperor and his brother went to war over the throne in 1156, and the winning side made a son behead his own father

Sutoku became emperor in 1123 as a small child. The Sekai Daihyakka records the court story that he was really the son of his great-grandfather, the retired emperor Shirakawa, and that his official father Toba called him "uncle-son." After Shirakawa died, Toba forced Sutoku to abdicate in 1141 in favour of Toba's three-year-old son by another consort. That boy died in 1155. Sutoku expected his own son to be named. Toba and his consort chose Sutoku's younger brother, Go-Shirakawa, and made Go-Shirakawa's son crown prince. The Fujiwara regent's house was split the same way: the brothers Tadamichi and Yorinaga fought over the headship. Toba died on the 2nd day of the 7th month of 1156. Sutoku and Yorinaga gathered warriors, among them Minamoto no Tameyoshi and several of his sons. Tameyoshi's eldest son Yoshitomo and Taira no Kiyomori joined the emperor. On the 11th the emperor's side attacked before dawn and won in half a day. Yorinaga died of an arrow wound. Sutoku was exiled to Sanuki. The court revived the death penalty, unused for more than 300 years. Kiyomori beheaded his uncle Tadamasa and his sons. Yoshitomo pleaded for his father's life, was refused, and beheaded Tameyoshi on the 30th. Sutoku died in exile in 1164, and people came to fear his angry spirit.