Minamoto no Sanetomo
Minamoto no Sanetomo was the third shogun of the Kamakura shogunate. The second son of Minamoto no Yoritomo and Hôjô Masako, he succeeded his brother Minamoto no Yoriie to become shogun on 1203/9/7. Sanetomo was famously assassinated by his nephew Minamoto no Kugyô in 1219.
In 1205, rumors that Hôjô Tokimasa was planning to have Sanetomo killed and replaced by Hiraga Tomomasa ended in Hiraga being killed and Tokimasa being forced to step down as ...., going into exile in Izu province.
The year 1213 saw another disturbance, as Wada Yoshimori led a force in attacking the shogun's mansion, as well as those of some of his closest relatives and chief officials. This event, known as the Wada Conflict or Wada Disturbance, ended with the uprising being suppressed, however, without Sanetomo or any of his closest relatives or advisors being killed.
Sanetomo's famous assassination took place at Tsurugaoka Hachimangû, where the shogun and numerous members of his court had just completed a court ceremony. Sanetomo's nephew Minamoto no Kugyô famously hid behind a massive gingko tree just to the side of the main stairs of the shrine, springing out to attack Sanetomo. While some accounts make no mention of Sanetomo's guards or retinue otherwise, even those which do make no mention of how the assassin was able to attack and kill the shogun so quickly and easily without having to go through his guards. In a complex series of events, Kugyô was killed shortly afterwards.
Following Sanetomo's death, his mother Hôjô Masako - sometimes known today as "the Nun Shogun" - became de facto ruler, taking no official title but overseeing governance and administration until Kujô Yoritsune, a court noble from Kyoto, was named shogun in 1226.
Minamoto no Yoriie