Tairo (chief minister) (大老)
Tairo was the highest post in the Edo bakufu government system, provisionally placed above Roju as an assistant to Shogun. In a broad sense, this term was used for indicating the highest responsible persons in a daimyo family or in an administrative body (Gotairo [Council of Five Elders] in the Toyotomi government were well known).
Summary
It was not a permanent post, and the number of its members was ordinarily one. Tairo was involved only in important policy decisions (called Taisei-sanyo), and was exempted from doing daily jobs, such as commuting to Hyojosho (the conference chamber) and handling daily affairs in monthly rotation.
In the cabinet officials of the Shogunate in the early Edo period, Tokugawa family members, who were deeply trusted by Ieyasu TOKUGAWA, such as Sadakatsu MATSUDAIRA and Tadaakira MATSUDAIRA, (Masayuki HOSHINA in the Ietsuna TOKUGAWA era occupied a similar position), or senior vassals, such as Naotaka II and Tadayo SAKAI (there are different opinions about whether both of Ii and Sakai were appointed to the Tairo post) played a role of Genro (an elder statesman), and it is considered that this Tairo post was established for having this role assumed by the senior member of Roju. In that sense, Tairo was rather a honorary post for Fudai daimyo (a daimyo who had belonged to the Tokugawa group before the battle of Sekigahara), but some at the post, such as Tadakiyo SAKAI and Naosuke II, concentrated power into their hands.
The first persons recorded as Tairo in the history were Toshikatsu DOI and Tadakatsu SAKAI (the lord of Obama Domain in Wakasa Province) who were promoted to the post in 1638 by Iemitsu TOKUGAWA.
After that, Tadakiyo SAKAI and Naozumi II assumed the post in the era of Ietsuna TOKUGAWA, and the style of Tairo as the highest governmental post was established in the era of Masatoshi HOTTA who was appointed the post by Tsunayoshi TOKUGAWA, the fifth shogun
Only the members of four families: Ii, Sakai (in the linage of Uta no kami [Director of the Bureau of Music]), Doi and Hotta were allowed to assume the Tairo post. A Fudai daimyo with 100,000 koku (approx. 180 liters/koku) rice yields was sometimes appointed the post, but he was called Tairo-kaku (Tairo level) instead of Tairo. For example, Yoshiyasu YANAGISAWA's post was Tairo-kaku. However, why the Tairo post had to be solely occupied by the members of the four families is not thoroughly clear, for example, descendents of Tadatsugu SAKAI, of Yasumasa SAKAKIBARA, and of Tadakatsu HONDA, who were important Fudai daimyo and called Tokugawa-shitenno (four generals of the Tokugawa clan) surpassing the Hotta family even in the amount of rice crop, were not appointed the post. Only Toshikatsu DOI was appointed the Tairo post from the Doi family. However, Toshihisa, the fourth head of the Doi family, could produce no heir, so the linage of the Doi family was once terminated, and use of the family name was permitted again with 70,000 koku rice yields (later 10,000 koku were added). Therefore, the family lost the qualification of a certain amount of rice yields for Tairo. However, the Doi family continued occupying an important post in the cabinet officials of the Shogunate, for example, Toshitsura DOI assumed the head of Roju (the post immediately under Tairo) after Tempo Reforms failed.
Two persons in the Tairo post were killed while in office. Masatoshi HOTTA was killed in the Edo castle by Wakadoshiyori, Masayasu INABA, who was his male cousin. Towards the end of the Edo bakufu, Naosuke II was killed in the Sakuradamongai incident by roshi (master-less samurai) of the Mito domain and Satsuma domain.
The four families that assumed the Tairo post
The Ii family
Summary of Tairo in domains
Tairo in a domain was a temporary post set up to assist the lord of the domain, for example, when the lord was young.. This post name was mainly used in big Shinpan domains (whose lords were relatives of the Tokugawa family), such as Aizu domain. Not all domains had this post.