Assassination
Under heavy snow on the evening of February 12, 1219 (Jōkyū 1, 26th day of the 1st month), Sanetomo was coming down from the Senior Shrine at Tsurugaoka Hachiman-gū after assisting to a ceremony celebrating his nomination to Udaijin. His nephew (the son of second shogun Minamoto no Yoriie) Kugyō (Minamoto no Yoshinari) came out from next to the stone stairway of the shrine, then suddenly attacked and assassinated him. For his act he was himself beheaded few hours later, thus bringing the Seiwa Genji line of the Minamoto clan and their rule in Kamakura to a sudden end.
Minamoto no Sanetomo was succeeded by Kujō Yoritsune as fourth shogun of the Kamakura shogunate.
Read more about this topic: Minamoto No Sanetomo