He was born at Kagoshima Castle, the fifth son of Shimazu Narioki, lord of the Satsuma domain. His mother was the concubine Lady Oyura. Because of his mother's low status he was made the adopted son of the senior Tanegashima family soon after birth, though he was still treated as a lord's son. His half-brother was Shimazu Nariakira, later praised as a wise ruler.
After returning to the main Shimazu house, he married a daughter of the Shigetomi Shimazu, the leading branch family, became their adopted son-in-law and moved to their residence in the castle town of Kagoshima. He later came of age and took the name Tadayuki. He is said to have loved learning and been devoted to kokugaku, poetry and history. This youthful learning later lent his politics a conservative tone.
Over the succession to their father, a faction backing his brother Nariakira and one backing Tadayuki clashed fiercely in a house dispute called the Oyura affair. With shogunal intervention their father retired and Nariakira became lord. Tadayuki had largely been put forward by the anti-Nariakira faction, and the brothers in fact got on well; Nariakira is said to have recognized his younger brother's talent.
His brother Nariakira had died the year before, and by his will Tadayuki's eldest son Mochihisa, later Tadayoshi, became lord. When their father Narioki, who had acted as guardian, also died this year, Tadayuki took real power as the lord's father. He promoted central figures of the Seichūgumi, a group of middle and lower-ranking retainers including Ōkubo Toshimichi, extending his influence.
To advance court–shogunate union, joining the court, the shogunate and the powerful domains, he marched to Kyoto with troops, a move seen as carrying on the will of his late brother Nariakira. In Kyoto he ordered the suppression of radical sonnō jōi retainers of his own domain gathered at the Teradaya inn in Fushimi to plot drastic action, and after a tragic clash many lives were lost. This was the Teradaya Incident.
Accompanying the court's envoy to Edo, he negotiated with senior shogunal officials. As a result he succeeded in having Hitotsubashi Yoshinobu made the shogun's guardian and Matsudaira Shungaku, former lord of Fukui, made president of political affairs. This is known as the Bunkyū reform. That the lord's father, neither a lord nor holding rank, could move shogunal politics astonished people at the time.
On his way back from Edo to Kyoto, at the village of Namamugi in Musashi, Satsuma retainers attending him attacked a party of British people who had crossed in front of the procession, leaving dead and wounded. This was the Namamugi Incident. By warrior etiquette of the time, disturbing a procession was not allowed, but the incident grew into a serious diplomatic problem with Britain.
A British squadron came to Kagoshima Bay demanding compensation for the Namamugi Incident, and an exchange of fire broke out with Satsuma. This was the Anglo-Satsuma War. The castle town suffered heavy damage, but the British side also took losses. Having learned the might of Western arms, Satsuma afterward drew closer to Britain and pressed ahead with modernizing its forces.
At Hisamitsu's proposal, the Council of Daimyō Advisers was created to bring powerful daimyō into the court's deliberations, and Hisamitsu was appointed an adviser along with Hitotsubashi Yoshinobu, Matsudaira Shungaku, Yamauchi Yōdō, Date Munenari, Matsudaira Katamori and others. But he clashed fiercely with Yoshinobu over whether to close the port of Yokohama, and the council soon collapsed.
In Kyoto he held the Council of Four Lords with Matsudaira Shungaku, Yamauchi Yōdō and Date Munenari, negotiating with shogun Yoshinobu over opening the port of Hyōgo and the treatment of Chōshū, but Yoshinobu seized the initiative and the effort failed. Giving up on cooperating with the shogunate, Satsuma turned decisively toward overthrowing it.
When the abolition of domains was carried out under the leadership of Saigō Takamori and Ōkubo Toshimichi, Hisamitsu was furious and, as a protest, had fireworks set off all night in the garden of his residence. He was the only former daimyō to show such open hostility to the abolition of domains. He continued to harbor deep dissatisfaction with the new government's abrupt reforms.
To placate Hisamitsu, the government made him cabinet adviser and then Minister of the Left, a high post in the Council of State. But Hisamitsu opposed policies such as changing hairstyles and dress to Western ways, kept demanding a return to the old system and clashed with the government. The next year he resigned as Minister of the Left and soon returned to Kagoshima, withdrawing from politics.
When Saigō Takamori and others raised troops and the Satsuma Rebellion began, the government, worried about Hisamitsu's stance, sent an envoy. Hisamitsu declared his neutrality and sent his sons to Kyoto. He is said to have taken temporary refuge on Sakurajima to avoid the fighting. All his life he never cut his topknot and kept wearing swords and Japanese dress.
In his last years in Kagoshima he collected historical records handed down in the Shimazu house and devoted himself to compiling histories. The government treated him generously, granting him the highest rank and the title of prince. He died at his Tamazato residence in Kagoshima and was given a state funeral. He is said to have insisted to the end that Saigō and Ōkubo had deceived him, a life of lasting mixed feelings about the Restoration.
Shimazu NariakiraSaigō TakamoriMatsudaira KatamoriŌkubo ToshimichiMatsudaira Shungaku (Yoshinaga)Komatsu Tatewaki (Kiyokado)Matsukata MasayoshiSanjō Sanetomi
Sakuma ShōzanIi NaosukeNabeshima Naomasa (Kansō)Yoshida TōyōIwase TadanariAbe MasahiroKatsu KaishūŌmura Masujirō
People of the Edo period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.