Yoritomo was the third son of Minamoto Yoshitomo, who, in 1159, attempted to destroy Taira Kiyomori (scion of another dominant military family, the Taira clan) in the Heiji Disturbance, in Kyōto province. He was defeated, however, and his son Yoritomo was captured and banished to Izu province (a peninsula southwest of Tokyo, now part of Shizuoka prefecture), where for 20 years he lived under Taira surveillance.
Yoritomo enlivened his rustication by seducing the daughter of his jailer, Itō Sukechika. The latter’s rage forced Yoritomo’s flight to the protection of Itō’s superior and neighbour, Hōjō Tokimasa, a Taira vassal whose hostile attitude to the Taira clan typified the contemporary split between court and country. Hōjō’s daughter also succumbed to Yorimoto’s blandishment but had to postpone marriage until 1180, when her official fiancé, the pro-Taira acting governor, had been eliminated. The essential feature, however—an understanding between Tokimasa and Yoritomo—was swiftly completed; and Yoritomo’s political pretensions now enjoyed support.
Meanwhile Taira Kiyomori, the head of the Taira clan, exercised his power over the imperial court, thus alienating Go-Shirakawa, the retired emperor. (At this period of Japanese history the emperor often lived in “retirement” away from court so he could rule without the hindrance of the highly detailed court ceremonials. This practice was known as insei. ) Most of the aristocracy and the heads of the great temples and shrines were also resentful of the Taira clan’s hold over the emperor.
In 1180 Minamoto Yorimasa, another member of the Minamoto clan, joined in a rebellion with an imperial prince, Mochihito-ō, who summoned the Minamoto clan to arms in various provinces. Yoritomo now used this princely mandate as a justification for his own uprising. Despite Mochihito-ō’s death, which occurred shortly before Yoritomo’s men were led into battle, he succeeded in gaining much support from the feudal lords in the eastern provinces. Many members of the Taira family also enrolled under Yoritomo’s banner, for they were disappointed with their meagre rewards from cousins at court. Yoritomo immediately advanced to Kamakura (about 10 miles [16 km] south of modern Tokyo) and established his headquarters there. As well as consolidating a hold over his own vassals in the Kantō area (around Tokyo), Yoritomo tried to organize the Minamoto followers under his direct control. He was loath to relinquish control to any of his various relatives, and to this end he established the Samurai-dokoro (“Board of Retainers”).
In 1183 Minamoto Yoshinaka, a cousin of Yoritomo, occupied the Hokuriku district and invaded Kyōto, the seat of the court. Go-Shirakawa, who always hoped to play off supporters, as well as enemies, against each other to regain some of the substance of imperial power, invited Yoritomo to put an end to Yoshinaka’s dangerously successful career; and Yoritomo accordingly crushed Yoshinaka at Kyōto. Yoritomo now established the Kumonjo (“Board of Public Papers”) and Monchūjo (“Board of Questioning”), setting up not only a military but also an independent political government in the east, yet one that was recognized by the central imperial court in Kyōto. In 1184 Yoritomo’s considerable armies, commanded by his two younger half-brothers Noriyori and Yoshitsune, the latter a brilliant commander of whom Yoritomo was jealous, were ranged against the Taira forces for what was hoped would be a climactic campaign, but decisive victory was not gained until the following year. After Minamoto’s next victory, the emperor supported Yoshitsune in efforts to restrain Yoritomo’s power. But Yoritomo immediately expelled Yoshitsune and imposed on the emperor the establishment of shugo and jitō throughout Japan, avowedly to capture Yoshitsune, though such arrangements were instrumental in making Yoritomo’s ascendancy nationwide. Soon after, Yoritomo succeeded in having Yoshitsune put to death.
Yoritomo gave his shugo, each placed in a province, the function of administering and policing the Minamoto vassals locally. The shugo also administered the judicial proceedings in cases of rebellion and murder, and they thus acquired something of a military hold over each province. To supervise individual estates, the more pacific office of jitō was created, which levied taxes and undertook the management of the estates. And, not surprisingly, both the shugo and the jitō became feudal lords. Through these institutions, Yoritomo was thus able to undermine the central government’s local administrative power, and subsequently he even made efforts to rule remote districts, such as Kyushu, Japan’s southernmost island.
In 1185 he destroyed Fujiwara Yasuhira, an independent noble of the Tohoku area, demonstrating his ambition to create a power structure independent of the capital, at Kyōto. In 1192, a few months after his old rival Go-Shirakawa’s death, Yoritomo, now with no one to hinder his ultimate ambition, titled himself seii taishōgun (“barbarian-quelling generalissimo”), becoming the supreme commander over the feudal lords. The Kamakura shogunate was now formally complete.
Minamoto Yoritomo is remembered as a founder of the bakufu, or shogunate, a system whereby feudal lords ruled Japan for 700 years. Defying the emperor, Yoritomo established shugo (constables) and jitō (district stewards) throughout the Japanese provinces, thus undermining the central government’s local administrative power, and in 1192 he acquired the title of supreme commander (shogun) over the shugo and jitō.
Yoritomo’s policies were designed to relieve the strain between the military lords and the court aristocrats, and the powerful temples and shrines. Thanks to the institutions of the shugo and jitō, relations between the court of Kyōto and Yoritomo’s government at Kamakura were fairly stable. Yoritomo died in 1199.
Yoritomo is often charged with cruelty, particularly in the killing of his cousin and brothers, but political circumstances of his time were difficult. He had above all to prevent discord among his vassals and the whole military class if his work was to attain the permanence that it did.
Quotes from others about the person
In the words of George Bailey Sansom, "Yoritomo was a truly great man … his foresight was remarkable, but so was his practical good sense in setting up machinery to match his own expanding power. "
He married into the Hōjō clan, led by Hōjō Tokimasa, marrying Tokimasa's daughter, Hōjō Masako.
