Sakuradamon Incident (1860–1862)

The Sakuradamon Incident was the assassination of Tairō Ii Naosuke on March 24, 1860, outside the Sakurada Gate of Edo Castle. Perpetrated by rōnin samurai from Mito and Satsuma domains, the attack stemmed from discontent over Ii's signing of the Harris Treaty and the Ansei Purge. The event severely damaged the shogunate's prestige and contributed to political shifts toward kōbu gattai.

Episodes

Background and detail

Background. Ii Naosuke was chosen as Tairō in 1858 by shōgun Tokugawa Iesada, a decision influenced by the Kii Party. He faced criticism for signing the 1858 Treaty of Amity and Commerce with the United States on behalf of the Tokugawa Shogunate, and from 1859 ports including Nagasaki, Hakodate, and Yokohama opened to foreign traders. His reinforcement of shogunal authority against regional daimyōs through the Ansei Purge drew further criticism.

Assassination. On March 24, 1860, during the Double Third Festival, Ii's entourage was attacked near the Sakurada Gate of Edo Castle. A group of 17 Mito and 1 Satsuma samurai cut down Ii as he approached the castle grounds. The incident occurred in Edo, where the shogunate headquarters were located.

Aftermath. The assassination dealt a severe blow to the shogunate's prestige, leading officials to initially deny Ii's death for a month, claiming he was merely injured and recuperating. The popular upheaval against foreign encroachment and the assassination forced the Bakufu to soften its stance and adopt the kōbu gattai policy suggested by Satsuma and Mito domains. The incident ushered in a decade of violence in Japan, and investigations into the surviving guards concluded in 1862 with verdicts to punish them.

People involved

Sources

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