the feudal system

Its the political, military, and social system in the Middle Ages, that’s based on the holding of lands in fief or fee and on the resulting relations between lord and vassal.

what role did he play in the feudal system?

Minamoto has a Japanese warrior and dictator, founder of the Kamakura shogunate. After a long struggle he led his clan, the Minamoto, to victory over the Taira in 1185. He became the first shogun, established his bakufu at Kamakura, and rewarded his retainers with estates strategically located throughout the country. These fiefs later became the basis of the power of the daimyo. Aided by scholars drawn from the imperial court, which minamoto controlled, he set up an secretarial network that soon became the only effective central government. His shogunate marked the beginning of a strong time in Japanese history. Zen Buddhism was officially sponsored, and the military virtues of bushido were educated. Minaotos system of centralized feudalism set the pattern of military rule in Japan.

minamotos reign 

Minamoto Yoritomo established the capital of his new military government in familiar surroundings at his home town of Kamakura, Plain once governed by his great grandfather. Positioned in a pretty valley on the northeastern edge of Sagami Bay it was both easy to defend and difficult to invade. Where Taira no Kiyomori had only limited military control in the immediate area around the imperial capital at Heian-kyo, minamotos military dominance was nationwide. Kiyomori exercised his authority from behind the scenes and largely through the old civil government structure in the tradition of the Fujiwara before him. minamoto declined to dethrone the emperor and created an entirely new and separate governmental structure closely linked with the old civil administration, but independent of it and separately based Kamakura.

The post of shogun was, in theory at least, purely military, so minamoto administration and those of later military rulers came to be known as the shogunate, bakufu, or "tent government," to distinguish it from the civil government in Heian-kyo.

key dates in minamotos life 

His first victory-

The Genpei War was in 1180–1185. It was a conflict between the Taira and Minamoto clans during the late-Heian period of Japan. It ended up in the fall of the Taira clan and the establishment of the Kamakura shogunate under Minamoto Yoritomo in 1192.

The name "Genpei"  comes from readings of the kanji "Minamoto" and "Taira". The conflict is also known in Japanese as the Jishō-Juei War . After the two eras between which it took place.

It began with Minamoto support for a different nominee to take the throne, in conflict with the Taira's nomination. The ensuing Battle of Uji took place just outside Kyoto, starting a five-year long war, concluding with a decisive Minamoto victory in the naval Battle of Dan-no-ura.

becoming the first shogun

This was a very big deal for becoming a shogun and especially at such a young age.

 Minamoto Yoritomo is one of the major figures in Japanese history. He established the first of the three shogunates (bakufu), that is, military governments, in Japanese history.