The head of the Minamoto clan Yoritomo was Japan's first shogun and set the wheels in motion for samurai domination of the country that would last until the mid-19th century.

Minamoto Yoritomo was born in 1147 and was almost immediately thrust into the rivalry between his family, the Minamoto, and the Taira after being exiled as a youth because of his role in a failed rebellion - called the Hoagie War - against their bitter opponents in 1160. The Minamoto and Taira families both had prestigious beginnings and both tried to control the imperial government through political intrigue, marriage, and force of arms. The last factor was what ultimately decided the argument in the ensuing Gempei Wars when Prince Mochihito, eager to succeed to the imperial throne, called on the Minamoto to crush the Taira, who had their own nominee for that position. 

After suffering defeat at the battle of Ishibashiyama in 1180 Yoritomo put military affairs into the hands of his more capable brother Yoshitsune and cousin Yoshinaka: both were excellent generals. After losing a fortress at Hiuchi to the Taira, Yoshinaka regrouped and defeated them at Kurikara valley and then at the battle of Shinowara. With these great victories Kyoto was open to him and this aroused Yoritomo's jealously when he entered the capital in triumph; even more so when he took the title of shogun. Because of this Yoritomo saw him as a rival rather than an ally and sent Yoshitsune to apprehend him. At Awazu Yoshinaka in 1184 was defeated and made a last stand with his most loyal companions and eventually died from an arrow wound. Yoshitsune went on to ensure Yoritomo's position by crushing the Taira at the famous battle of Ichinotani and then annihilating the clan's last remnants in 1185 at the naval battle of Dan no Ura, which ultimately ended the Gempei Wars.

With the annihilation of the Taira clan Yoritomo established the Kamakura bakufu or 'tent government' and became shogun in 1192. Originally the title was a temporary office and was given to a samurai with a commission to hunt rebels against the imperial throne. Now it was permanent and was to last until as recently as 1867 when the last shogun, Tokugawa Yoshinobu, renounced his power to the imperial throne thus heralding the Meiji era and the subsequent modernisation of Japan. The shogunate, as the office was called, was in reality a military dictatorship relegating the imperial court in Kyoto to a backseat and reducing the power of the emperor so he was nothing more than a symbolic figurehead, though still very influential. Yoritomo completely overhauled the government, abolishing some offices and creating new ones. Although his skills as a general were questionable his talents as an administrator were substantial, maintaining control over the complex bureaucracy he had created. The civil government was over and the age of the samurai had begun.

Minamoto Yoritomo was not shogun for very long and died in 1199 after a riding accident. Problems continued after his death when his widow Masako plotted and schemed against the Minamoto as she was a daughter of the Hojo clan which was itself descended from the Taira. She sided with her own family against the Minamoto and even had her own children targeted by assassins. Eventually the Hojo clan began to dominate the bakufu and Yoritomo's successors were picked off by assassins: Yoriie was murdered in 1204 and Sanetomo followed in 1219. Despite this, tradition held that in order to become shogun one had to trace their lineage back to the original Minamoto family. In this way the founders of the shogunate lived on.

Further Reading

The Samurai - Anthony J Bryant.

Samurai Commanders 1 (Osprey Publishing) - Stephen Turnbull.