Satsuma (薩摩藩) was a feudal domain located in modern-day Kagoshima prefecture, in southwestern Kyushu. Satsuma was ruled by the Shimazu clan (島津氏, Shimazu-shi), whose fief, the Satsuma han (藩, domain), extended over the provinces of Satsuma (薩摩), Ōsumi (大隅), both comprising present-day Kagoshima prefecture, and Hyūga (日向), which corresponds to the modern-day Miyazaki prefecture.
The Shimazu were a branch of the Minamoto (源) clan, one of four great clans that dominated Japanese politics during the Heian period. They were among the most powerful and the wealthiest of the tozama daimyō (“outside” daimyō clans, that were not vassals of the Tokugawa clan) and ruled from Kagoshima Castle in Kagoshima city. With about 770,000 koku (石 or 石高, one koku being the equivalent of 278.3 litres), their rice yields (石高 kokudaka) were the second highest in feudal Japan. Due to their military power and prosperity they were able to maintain their territories until the end of the Edo Period.
In 1609, the shogunate granted the request of Shimazu Tadatsune (島津 忠恒) to invade the Ryūkyū Kingdom, allowing him to turn it into a vassal state and using it to effect trade with China. Due to the maritime prohibitions imposed in line with the sakoku (鎖国, “locked country”) policy in the 1630s, Satsuma enjoyed the privileged position of acquiring foreign goods and knowledge on behalf of the Tokugawa shogunate, thus further increasing their wealth and status.
Owing to their special status, Satsuma was able to benefit from other unique privileges as well, such as maintaining more than just one castle per han, which allowed the Satsuma daimyō to establish “sub-domains” by giving their own retainers the permission to erect castles. Satsuma’s role can well be described as a “shogunate within the shogunate”. They were also partially exempted from sankin kōtai (参勤交代, “alternate attendance”), a regulation that forced all daimyō to temporarily reside in Edo every each year in order to effectively control them. The Satsuma daimyō had to travel to Edo only every other year.
Due to its fair degree of autonomy, the Satsuma domain tended to oppose the bakufu and its policies. In the 1850s however, Shimazu Nariakira tried to appease the Tokugawa shogunate by arranging a marriage between his adopted daughter and shogun Tokugawa Iesada. Satsuma aimed at closer contacts to China and the Western powers whose ships frequently visited the Ryūkyū islands.
When the shogunate sent two expeditionary forces against the Chōshū domain, which openly supported the sonnō jōi (尊皇攘夷, “Revere the Emperor, Expel the Barbarians”) movement, in order to make an example of Chōshū, Satsuma led by Saigo Takamori and Ōkubo Toshimichi switched sides, forming the Satsuma-Chōshū Alliance (薩摩長州同盟 satsuma chōshū dōmei) against the shogunate in 1866. The Tokugawa forces were finally defeated in the Boshin War in 1868/69.
Former retainers of Satsuma and Chōshū dominated the politics and the army after the Meiji Restoration. In 1877 however, growing discontent among the samurai class led to the Satsuma Rebellion under Saigo Takamori.
Map of Satsuma han (Japan Reference/JREF)
Shimazu Hisamitsu (島津久光) was Satsuma regent for his son Tadayoshi, the 12th and last damiyō, from 1858 and instrumental in forging the alliance with Chōshū and Tōsa against the Tokugawa shogunate (Image credit)