Minamoto no Sanetomo
Yoritomo's second son and third "shōgun" Minamoto no Sanetomo spent most of his life staying out of politics and writing poetry, but was nonetheless assassinated in February 1219 by his nephew Kugyō under the giant ginkgo tree whose trunk still stood at Tsurugaoka Hachiman-gū until it was uprooted by a storm in the early hours of March 10, 2010. Kugyō himself, the last of his line, was beheaded as a punishment for his crime by the Hōjō just hours later. Barely 30 years into the shogunate, the Seiwa Genji dynasty who had created it in Kamakura had ended.