was a daimyō

Daimyo

is a generic term referring to the powerful territorial lords in pre-modern Japan who ruled most of the country from their vast, hereditary land holdings...

 during Bakumatsu period Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, who served as chief senior councilor (Rōjū

Roju

The ', usually translated as Elder, was one of the highest-ranking government posts in Tokugawa Japan. The term refers either to individual Elders, or to the Council as a whole; under the first two shoguns, there were only two Rōjū...

) in service to the Tokugawa Shogunate

Tokugawa shogunate

The Tokugawa shogunate, also known as the and the , was a feudal regime of Japan established by Tokugawa Ieyasu and ruled by the shoguns of the Tokugawa family. This period is known as the Edo period and gets its name from the capital city, Edo, which is now called Tokyo, after the name was...

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Biography

Mizuno Tadakiyo was the eldest son of Mizuno Tadakuni

Mizuno Tadakuni

was a daimyō during late-Edo period Japan, who later served as chief senior councilor in service to the Tokugawa Shogunate. He is remembered for having instituted the Tenpo Reform.-Biography:...

, the daimyō of Hamamatsu Domain

Hamamatsu Domain

was a Japanese domain of the Edo period, located in Tōtōmi Province. It was centered on what is now Hamamatsu Castle in what is now the city of Hamamatsu in Shizuoka Prefecture....

 and chief senior councilor (Rōjū

Roju

The ', usually translated as Elder, was one of the highest-ranking government posts in Tokugawa Japan. The term refers either to individual Elders, or to the Council as a whole; under the first two shoguns, there were only two Rōjū...

) in service to the Tokugawa Shogunate

Tokugawa shogunate

The Tokugawa shogunate, also known as the and the , was a feudal regime of Japan established by Tokugawa Ieyasu and ruled by the shoguns of the Tokugawa family. This period is known as the Edo period and gets its name from the capital city, Edo, which is now called Tokyo, after the name was...

. After the failure of the Tenpo Reform, Tadakuni was forced into retirement and exile, and turned the leadership of the Mizuno clan

Mizuno clan

The was a Japanese clan which claimed descent from the Seiwa Genji branch of the Minamoto clan. In the Edo period, the Mizuno clan produced many men who were fudai daimyo serving the Tokugawa shogun, as well as countless families of hatamoto...

 and the position of daimyō of Hamamatsu Domain to Tadakiyo in 1845.

However, the same year, Tadakuni was reassigned to Yamagata Domain

Yamagata Domain

Yamagata Domain was a Japanese fief , located in Dewa province, in the Tōhoku region . Modern-day Yamagata Prefecture is roughly contiguous with the domain, and its capital city, also called Yamagata, grew up out of the daimyo's castle town...

 (50,000 koku

Koku

The is a Japanese unit of volume, equal to ten cubic shaku. In this definition, 3.5937 koku equal one cubic metre, i.e. 1 koku is approximately 278.3 litres. The koku was originally defined as a quantity of rice, historically defined as enough rice to feed one person for one year...

) in Dewa Province

Dewa Province

is an old province of Japan, comprising modern-day Yamagata Prefecture and Akita Prefecture, except for the city of Kazuno and the town of Kosaka. It was sometimes called .-Historical record:...

. After the pardon of his father in 1851, Tadakuni’s fortunes improved. Within the shogunal administration, he received the post of Jisha-bugyō

Jisha-bugyo

was a "commissioner" or an "overseer" of the Tokugawa shogunate in Edo period Japan. Appointments to this prominent office were always fudai daimyō, the lowest-ranking of the shogunate offices to be so restricted...

(Commissioner of Shrine and Temples) and wakadoshiyori

Wakadoshiyori

The ', or "Junior Elders", were high government officials in 17th century Tokugawa Japan. The position was established around 1631, but appointments were irregular until 1662....

(Junior Councilor). In 1862, he became a Rōjū in the service of Shogun

Shogun

A was one of the hereditary military dictators of Japan from 1192 to 1867. In this period, the shoguns, or their shikken regents , were the de facto rulers of Japan though they were nominally appointed by the emperor...

 Tokugawa Iemochi

Tokugawa Iemochi

was the 14th shogun of the Tokugawa shogunate of Japan, who held office 1858 to 1866. During his reign there was much internal turmoil as a result of Japan's first major contact with the United States, which occurred under Commodore Perry in 1853 and 1854, and of the subsequent "re-opening" of...

.

As Rōjū, he worked with Oguri Tadamasa in the construction of Yokosuka Naval Arsenal

Yokosuka Naval Arsenal

was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy, and was located at Yokosuka city, Kanagawa prefecture on Tokyo Bay, south of Yokohama...

 as part of the Tokugawa shogunate’s efforts to modernize Japan’s military.

He retired from public life in 1866 on the death of Shogun Tokugawa Iemochi, and was succeeded at Yamagata by his son Mizuno Tadahiro. Mizuno Tadakiyo was married to a daughter of Inoue Masahari, a fellow Rōjū and daimyō of Tanagura Domain

Tanagura Domain

The ' was a Japanese domain of the Edo period. Its headquarters was in modern-day Tanagura, Fukushima. It was founded in 1603, when Tachibana Muneshige was given the territory by Tokugawa Ieyasu.-List of lords:...

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