The Sakuradamon Gate Incident

On March 3, 1860 (Ansei 7) during the end of the Tokugawa Shogunate, Ii Naosuke, the Chief Advisor of the Edo Shogunate, was assassinated outside Sakuradamon Gate. Sakuradamon Gate was one of the gates inside Edo Castle. There was strong resentment against Ii, the Chief Advisor, among the Sonno Joi faction, over the issue of the Shogun's succession and the signing of the Ansei Five-Nation Treaty (Ansei Treaty of Commerce and Trade) in violation of Imperial Rule, but this resentment grew even stronger as the Ansei Purge progressed. From around the latter half of 1858, the Satsuma clan had been planning to cooperate with the Mito, Choshu, Echizen, and Inshu clans to "purge the Shogunate," but in the following year, 1859, the Mito and Satsuma clans had been actively interacting with each other, and the Sui-Satsuma alliance took shape. In other words, as the shogunate intensified its pressure on the Mito domain over the issue of the return of the Imperial decree regarding the "Bogo no Himitsu Imperial Rescript," the resentment of the extremists grew, and on the other hand, the extremists in the Satsuma domain were also frustrated. After January 1860, a pact of "righteous action" was made between volunteers from both the Sui and Satsuma domains, and on the morning of March 3, 18 people attacked Ii's procession outside the snowy Sakuradamon Gate. These 18 men were made up of 17 samurai from the Mito domain with Seki Tetsunosuke as the overall commander (in addition to Seki, they also included Okabe Sanjuro, Saito Kenmotsu, Sano Takenosuke, Ozeki Washichiro, Hirooka Nenojiro, Inada Juzo, Moriyama Shigenosuke, Kaigo Sakinosuke, Kurosawa Chuzaburo, Yamaguchi Tatsunosuke, Sugiyama Yaichiro, Masuko Kinpachi, Hasuda Ichigoro, Koibuchi Kaname, Hiroki Matsunosuke, and Mori Gorokuro) and one samurai from the Satsuma domain (Arimura Jizaemon). Their "Purpose for Execution of Traitorous" clearly indicated that they intended to reform the shogunate by slaughtering those in the Ii faction, and not to overthrow the shogunate. However, with the assassination of the Chief Minister in the middle of the day, the decline of the shogunate became public knowledge and marked a turning point in the political situation at the end of the Edo period.

[Akira Tanaka]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

幕末期の1860年（安政7）3月3日、江戸幕府の大老井伊直弼(なおすけ)が桜田門外で暗殺された事件。桜田門は江戸城内郭門(うちぐるわもん)の一つ。将軍継嗣(けいし)問題や安政(あんせい)五か国条約（安政通商条約）の違勅調印などをめぐって大老井伊への反感は、尊攘(そんじょう)派などに強くあったが、安政の大獄の進行で一段と強まった。58年後半ころから薩摩(さつま)藩有志の間には、水戸・長州・越前(えちぜん)・因州の諸藩と提携して幕府の「除奸(じょかん)」計画が企てられていたが、翌59年になると、水戸藩と薩摩藩有志の交流が盛んとなり、水・薩提携が具体化していった。すなわち、水戸藩への「戊午(ぼご)の密勅」をめぐる勅諚(ちょくじょう)返還問題への幕府の圧力が強まるや、激派の反感は高まり、他方、薩摩藩でも激派の不満が鬱屈(うっくつ)していた。60年1月以降、水・薩両藩有志の「義挙」の盟約が結ばれ、3月3日朝、18名が雪の桜田門外に井伊の行列を襲った。この18名は、関鉄之介を総指揮者とする水戸藩士17名（関のほか、岡部三十郎、斎藤監物(けんもつ)、佐野竹之介、大関和七郎、広岡子之次郎(ねのじろう)、稲田重蔵、森山繁之介、海後磋磯之介(かいごさきのすけ)、黒沢忠三郎、山口辰之介、杉山弥一郎、増子金八、蓮田(はすだ)市五郎、鯉淵要人(こいぶちかなめ)、広木松之介、森五六郎）と薩藩士1名（有村次左衛門(じざえもん)）よりなる。彼らの「斬奸(ざんかん)趣意書」では、井伊一派の斬戮(ざんりく)による幕府の改革を企図したもので、倒幕を意図したものでないことがわかる。しかし、白昼大老が暗殺されたことで、幕府の衰退が公然となり、幕末期政局の一つの転機となった。

［田中　彰］

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