 It was now reduced to only 50,000 "koku".Mizuno Tadakiyo served as "Jisha-bugyō" and "wakadoshiyori" in the shogunal administration and in 1862, became a "rōjū" in the service of "Shōgun" Tokugawa Iemochi.During the Boshin War, Yamagata Domain was a member of the Ōuetsu Reppan Dōmei; although its final daimyō, Mizuno Tadahiro was only 13 years old.