Matsudaira Sadayasu

Matsudaira Sadayasu (松平 定安, May 5, 1835 – December 1, 1882) was a Japanese daimyō of the late Edo period, who ruled the Matsue Domain.

Matsudaira Sadayasu was born in 1835, the seventh son of Matsudaira Naritaka of the Tsuyama Domain. In 1853, he was adopted by Matsudaira Naritoki, the 9th lord of Matsue. Soon after, Naritoki retired, and Sadayasu became lord of Matsue.

During Sadayasu's tenure as lord, Matsue samurai were deployed to security duties in Osaka and Kyoto. For much of the Bakumatsu period, the policy of Matsue was pro-shogunate.

In 1868, Matsue forces took part in the Boshin War on the side of the Meiji government. The same year, there was a peasant revolt in the Oki Islands, which was part of Matsue territory. Sadayasu dispatched troops to quell it by force; he withdrew after receiving complaints from Satsuma and Chōshū.

Sadayasu was relieved of his duties as daimyō in 1871, due to the order for the abolition of the domains. He retired from family headship in 1872, in favor of his adopted son Naotaka. However, as Naotaka retired in 1877, Sadayasu again assumed headship until 1882. In 1882 he passed headship to his 3rd son Naosuke. A few weeks later he died, at age 48.