Early life
Yoritomo was the third son of Minamoto no Yoshitomo and his official wife, Yura-Gozen, daughter of Fujiwara no Suenori, High Priest of Atsuta Shrine and a member of the powerful Fujiwara clan. Yoritomo was born in the family villa, on the western side of Atsuta Shrine, in Atsuta, Nagoya, Owari Province (present-day Seigan-ji). At the time, his grandfather Minamoto no Tameyoshi was the head of the Minamoto clan. His childhood name was Oniwakamaru (鬼武丸). He was a descendant of Emperor Seiwa.
In 1156, factional divisions in the court erupted into open warfare within the capital. The cloistered Emperor Toba and his son Emperor Go-Shirakawa sided with the son of Fujiwara regent Fujiwara no Tadazane, Fujiwara no Tadamichi as well as Taira no Kiyomori (heir of the Taira clan at the time), while Cloistered Emperor Sutoku sided with Tadazane's younger son, Fujiwara no Yorinaga. This is known as the Hōgen Rebellion.
The Minamoto clan were split. The head of the clan, Tameyoshi, sided with Sutoku. However, his son, Yoshitomo (father of Yoritomo), sided with Toba and Go-Shirakawa, as well as Kiyomori. In the end, the supporters of Go-Shirakawa won the civil war, thus ensuring victory for Yoshitomo and Kiyomori. Sutoku was placed under house arrest, and Yorinaga was fatally wounded in battle. Tameyoshi was executed by the forces of Yoshitomo. Nonetheless, Go-Shirakawa and Kiyomori were ruthless, and Yoshitomo found himself as the head of the Minamoto clan, while Yoritomo became the heir.
Yoritomo and the Minamoto clan descended from the imperial family on his father's side. Nonetheless, in Kyoto, the Taira clan, now under the leadership of Kiyomori, and the Minamoto clan, under the leadership of Yoshitomo, began to factionalize again.
Four years later, Fujiwara no Nobuyori made request for a greater position in the government, Ex-Emperor Go-Shirakawa denied the request under the advice of the Taira backed Fujiwara no Michinori (Also known as Shinzei). This led to Nobuyori joining forces with Yoshitomo and the Minamoto clan to prepare for a coup d'état. This would spark the conflict known as the Heiji rebellion.
In December 1159, Kiyomori left Heian-kyō on a pilgrimage. Seeing an opportunity, Minamoto gathered hundreds of men, attacked Sanjō Palace, and kidnapped Ex-Emperor Go-Shirakawa and current Emperor Nijō. Next the Minamoto attacked Shinzei's mansion. Shinzei was able to escape, but was captured and decapitated shortly thereafter. Kiyomori returned, freed both the retired and current Emperor, and defeated the Minamoto at the Battle at Rokuhara. Yoshitomo fled the capital but was later betrayed and executed by a retainer.
Only Yoritomo and his younger brothers were spared on account of their young age, though they were exiled to temples to become monks. Taira no Kiyomori and the Taira clan were now the undisputed leaders of Japan.
Yoritomo grew up in exile. He married into the Hōjō clan, led by Hōjō Tokimasa, marrying Tokimasa's daughter, Hōjō Masako. Meanwhile, he was notified of events in Kyoto.
