**Sakashitamon Incident** (坂下門外の変) was an attack that took place on 13 February 1862 (the 2nd year of Bunkyū) outside Sakashita Gate of [[Edo Castle]], in which six ronin of the [[Mito Domain]] who supported [[Sonnō jōi]] attacked the [[Rōjū]] [[Andō Nobumasa]] and wounded him.

## Background

After [[Ii Naosuke]], the [[Tairō]], was assassinated in the [[Sakuradamon Incident]], [[Andō Nobumasa]], who together with [[Kuze Hirochika]], the [[Rōjū]], led the shogunate, inherited Naosuke's policy of opening the country and, in order to restore the authority of the shogunate, pursued [[Kōbu gattai]]. Under this policy, the shogunate decided to arrange a marriage between [[Kazunomiya Chikako]], the younger sister of the Emperor, and the shogun. However, activists who supported Sonnō jōi opposed this and grew angry at Nobumasa and others.

In July 1860, the first year of Manen, Saimaru Tatemaki, Nomura Tsunenosuke, Sumiya Toranosuke and others of the [[Mito Domain]] and [[Katsura Kogorō]], Matsushima Kojō and others of the [[Chōshū Domain]] agreed to cooperate and act together (the Heishinmaru Covenant, the Mito–Chōshū Covenant). Accordingly, they planned the assassination of Nobumasa and an attack on foreigners residing in [[Yokohama]]. However, within the Chōshū Domain the [[Kōbu gattai]] theory of [[Nagai Uta]] came to dominate the domain's mainstream, making it difficult for domain retainers to take part. The Chōshū side proposed postponing the plan, but the Mito side, fearing that they would miss their opportunity, decided to carry out the plan independently without Chōshū's support.

The Mito activists, in coordination with the Confucian scholar Ohashi Tōsha and his faction of [[Utsunomiya Domain]], proceeded with the plan to assassinate Nobumasa. Initially it was scheduled to be carried out on 15 December, but for various reasons it was postponed to 28 December, and then again to 15 January. The reason they aimed for that time was that on the day of the [[Daeboreum]] (上元) ceremonial rites, many [[Daimyō]] entered the castle and paid their respects to the shogun. However, on 12 January, just before the attack, Ohashi Tōsha and other participants from Utsunomiya were arrested by the shogunate after part of the plan was revealed. Therefore, they could not proceed according to the original plan, and the attack was carried out by the remaining members centered on the Mito activists.

## Course of Events

At about 8 a.m. on 15 January 1862 (the 2nd year of Bunkyū), when Nobumasa's procession left the lord's residence to enter the castle and reached the area outside Sakashita Gate, six people attacked the procession: the Mito Domain ronin Hirayama Yōsuke, Oda Hikosaburō, Kurosawa Gorō, Takahata Shōjirō, Kōno Takeshi, a doctor from Shimotsuke Province[^1], and Kawamoto Tōtarō, a doctor from Echigo Province. Kawabe Hidari Jiemon, another Mito Domain ronin, also took part in the plan, but he arrived late and was unable to join the attack. (Kurosawa Gorō and Takahata Shōjirō had also participated in the [[First Dōzenji Incident]].)

First, Kawamoto Tōtarō pretended to make a direct appeal and jumped out in front of the procession, firing a gun at the palanquin. The bullet missed the palanquin and hit the leg of a bodyguard, and at the signal of this shot, the other five rushed into the procession. Taking advantage of the brief confusion among the guards, Hirayama Yōsuke thrust his sword into the palanquin, inflicting a minor wound on Nobumasa's waist, and then fled alone into the castle.

After the [[Sakuradamon Incident]], security for the Rōjū as well as for lords going to the castle became even tighter. On the day of the attack, more than fifty guards were on duty, so the six ronin were unable to achieve their goal of assassination, and all of them were killed in the fighting. Dozens of the bodyguards were also wounded, but none died.

Kawabe, who had arrived late, delivered a statement justifying the assassination (斬奸趣意書)[^2] at the Chōshū lord's residence and then committed [[Seppuku]].

## Results

Although the attempt to assassinate [[Rōjū]] [[Andō Nobumasa]] failed, the attack on a member of the shogunal government, which led to the [[Sakuradamon Incident]], greatly damaged the authority of the shogunate. Following this incident, Nobumasa was dismissed from his post as Rōjū in April, ordered into retirement and confinement in August, and his [[Iwaki Domain]] of 20,000 koku was reduced in revenue.

## Notes

[^1]: From Yoshida village (吉田村), [[Kawachi District]], Shimotsuke Province
[^2]: This political action was not, from the beginning, a movement carried out according to a systematic plan; it was adopted after plans for an armed uprising were sought and frustrated.