保元之亂
On July 20, 1156 ("Hōgen 1, 2nd day of the 7th month"), the ex-Emperor Toba died at the age of 54. Soon afterwards, the Hōgen Rebellion broke out - Yorinaga had mustered several hundred warriors to try to press Sutoku's claim and usurp Go-Shirakawa's title. However, Go-Shirakawa gained the support of the two most powerful warrior clans, the Taira and the Minamoto, through their leaders, Minamoto no Yoshitomo and Taira no Kiyomori. Together, they easily defeated the armies of Sutoku leaving Go-Shirakawa as the sole imperial ruler. Sansom argues that because the course of the insurrection was dictated by the military clans, this moment represents a turning point in the nature of Japanese politics; the imperial clan had lost all authority and the military clans now controlled the political landscape. Sansom develops this point to assert that an intrinsic part of the "insei" system was the security it granted the emperors, as they often entered religion; the sacrosanctity of monks and priests was an intrinsic part of Japanese culture. Given that Sutoku was overthrown by the military clans and Go-Shirakawa, his position cannot truly be considered to have been secure, Sansom argues, and so the Hōgen Rebellion represents the end of the "insei" system.