Ii Naosuke Is Appointed Tairō

In the fourth month of the Japanese calendar in 1858, shogun Tokugawa Iesada appointed Hikone lord Ii Naosuke as tairō, the shogunate’s chief senior councillor. The government was confronting both negotiations for a commercial treaty and competition over an heir to the childless shogun. Ii’s appointment placed a leading supporter of the Kii candidate Yoshitomi at the center of those decisions.

A surviving oath copy is dated the twenty-fifth day, two days after the appointment. In Ii’s own handwriting, it sets out commitments of service to the shogunate, followed by religious oath language. The copy bears a Kumano sacred seal on its reverse; the formal original submitted to the shogun required a blood seal beneath the signature.

Ii subsequently authorized the American commercial treaty’s signature without prior imperial approval and helped secure Yoshitomi’s selection as heir. Those acts used the authority acquired with the office and intensified opposition. The appointment and oath establish his position and formal obligations; they do not reveal Iesada’s private reasoning or assign Ii the diplomats’ work of negotiating each treaty clause.