Incident at Sakuradamon
- Date: 1860/3/3
- Japanese: 桜田門外の変 (Sakuradamon gai no hen)
The Tairô Ii Naosuke was assassinated just outside the Sakuradamon (Sakurada Gate) of Edo castle, by a group of eighteen men, on 1860/3/3. The plot was organized and executed chiefly by rônin from Mito han, possibly at the direction of the lord of Mito, Tokugawa Nariaki, whose supporters had been pushed out of government by Naosuke in the Ansei Purges. The event is cited among those which led to the downfall of the Tokugawa shogunate eight years later.
The attack took place in the early morning, at the Hour of the Dragon. Records from the time indicate that it had snowed heavily in the preceding hours. The perpetrators are traditionally given as the former Mito domain retainers (ronin) Seki Tetsunosuke, Inada Jûzô, Yamaguchi Tatsunosuke, Koibuchi Kaname, Hirooka Nenojirô, Kurosawa Chûzaburô, Sano Takenosuke, Saitô Kenmotsu, Hasuda Ichigorô, Mori Gorokurô, Moriyama Shigenosuke, Ozeki Washichirô, Kaigo Sakinosuke, Sugiyama Yaichirô, Okabe Sanjûrô, Hiroki Matsunosuke, and Mashiko Kinpachi, along with former Kagoshima han retainer Arimura Jizaemon. They first met at or near Atago Shrine in the Shiba neighborhood of Edo. At the Hour of the Dragon then then attacked Naosuke's entourage on its way into the castle, just outside the Sakuradamon, eventually taking Naosuke's head.
A number of Naosuke's attendants, including Kada Kurota, Kasai Chûzaemon, Sawamura Gunroku, and Nagata Tarôbei, were also killed, while many others suffered injuries. Inada Jûzô also died in the fighting.
Once the attack was done, Yamaguchi Tatsunosuke and Koibuchi Kaname committed suicide at the riverbank at Yaesu, and Arimura Jizaemon and his son Jirô did the same at the Tatsunoguchi gate of the castle. Kurosawa Chûzaburô, Hasuda Ichigorô, Saitô Kenmotsu, and Sano Takenosuke turned themselves in at the mansion of Rôjû Wakisaka Yasuori, and Ozeki Washichirô, Mori Gorokurô, Sugiyama Yaichirô, and Moriyama Shigenosuke turned themselves in at the Kumamoto domain mansion. Seki Tetsunosuke, Okabe Sanjûrô, Hiroki Matsunosuke, Kaigo Sakinosuke, and Mashiko Kinpachi escaped to various locations and went into hiding. Sano Takenosuke died of his injuries later on the same day of the attack, and Saitô Kenmotsu several days later. Co-conspirators involved in the planning of the attack but not in the attack itself included Arimura Yûsuke (elder brother of Jizaemon), Kaneko Magojirô, and Satô Tetsusaburô; once they heard the attack was successful, these three fled Edo for Kyoto, but were apprehended at Yokkaichi post-station by Kagoshima officials. Magojirô and Tetsusaburô were brought to Fushimi and then later transported to Edo, while Yûsuke was sent back to Kagoshima. Yûsuke later committed suicide after returning to Kagoshima.
Those who turned themselves in were all then held in the custody of Kumamoto domain for a time, before being split up and placed into the custody of Usuki, Toyama, Muramatsu, Ichinoseki, and Zeze domains; though Hikone requested that they be turned over to Hikone authorities, the shogunate denied this request, and interrogated those in custody several times.
Naosuke's death was initially concealed, not announced, for some time at the orders of the shogunate, presumably in the hopes of avoiding further turmoil. The shogunate bestowed a number of gifts upon the Ii house, including sea bream, Korean ginseng, and rock candy, in conjunction with official condolences. A number of measures were put into place to increase security around the castle and the daimyo mansions, including cutting off general access to a number of the main gates to Edo castle (with shogunate high officials becoming the only ones allowed to enter those gates), and requiring Mito domain to inform the shogunate of any domain officials or retainers who enter the city.
- Gallery labels, Edo-Tokyo Museum.
- Ishin Shiryô Kôyô 維新史料綱要, vol 3 (1937), 275-284, 287, 290, 295.