Yoritomo defeated the Taira clan .
Yoritomo became de facto ruler of much of Japan and founder of the Kamakura shogunate , an institution destined to last 141 years and to have immense repercussions over the country 's history .
Defeating the Taira clan , Yoritomo became de facto ruler of much of Japan and founder of the Kamakura shogunate , an institution destined to last 141 years and to have immense repercussions over the country 's history .