His mother was a daughter of Iriki'in Shigesato, Sesshō. Shimazu Yoshihiro, Shimazu Toshihisa and Shimazu Iehisa were his brothers. He is said to have been born in Izaku Castle in 1535. His childhood name was Torajumaru but he went by the name of Matasaburō. On his coming-of-age, he took the name of Tadayoshi but after receiving a kanji from the shōgunAshikaga Yoshiteru, changed to Yoshitatsu. He later changed his name to Yoshihisa. He married his own aunt and after her death, married his relative, a daughter of Tanegashima Tokitaka. His knowledge of culture is not known but Hosokawa Yusai taught him classic literatures and Kampaku, Konoe Wakihisa, who was skilled in waka and renga, is believed to have frequented Yoshihisa's house. He initially looked favourably on Christian missionaries such as Luís de Almeida.
Unifying Kyushu
In 1566, he succeeded his father as the head of Shimazu clan, becoming the clan's sixteenth leader. Working together with his brothers Yoshihiro, Toshihisa, and Iehisa, he launched a campaign to unify Kyūshū. Starting in 1572 with a victory against Itō clan at the battle of Kizaki and the Siege of Takabaru in 1576, Yoshihisa continued to win battles. In 1578, he defeated the Ōtomo clan at the battle of Mimigawa, though he did not take their territory,; he took Minamata castle in 1581 with a force of 115,000 men; In early 1584, he was victorious in Battle of Okitanawate against Ryūzōji clan and defeated the Aso clan. By the middle of the 1584s, the Shimazu clan controlled most of Kyūshū with the exception of Ōtomo's domain and unification was a feasible goal. In 1586, he took Iwaya castle resulted after the Shimazu invasion of Chikuzen Province.
During Shimazu's attempt to unify Kyushu, other clans appealed to Toyotomi Hideyoshi for help; in 1584 the Otomo and Ryuzoji asked Hideyoshi for aid, and though he had been unable to help at that time, in 1585 he interceded, requesting that Yoshihisa make peace. In response, Yoshihisa derided his attempt to intervene, not seeing Hideyoshi as being in a position to invade Kyushu. In 1586, the Otomo leaders travelled to Osaka itself, seeking to persuade Hideyoshi to help. Hideyoshi was impressed with this embassy, and presumably agreed to help; Yoshihisa, seeing that Hideyoshi was prepared to invade, sent a message to Hideyoshi, claiming that he had attacked the other clans in self-defence. In 1587 Kyushu Campaign by Toyotomi Hideyoshi begin. The Ōtomo forces led by Myorin, were supported by armies under Sengoku Hidehisa, Chōsokabe Motochika and Sogō Masayasu, delayed Shimazu forces and weakened them in preparation for the arrival of Hideyoshi's armies. Hideyoshi mobilised a force of 200,000 soldiers and 20,000 pack animals, transporting supplies for an even larger army of 300,000 men. Toyotomi Hidenaga led the vanguard of 25,000 men and 3,000 horses. By April 1587 Hideyoshi had reached the straits at Shimonoseki, moving through Chikuzen and Chikugo to attack Yoshihisa in Higo. At this point Mōri vassals joined Hidenaga's force, as the Mōri had been recently suppressed. Hidenaga then drove back the Shimazu forces in Hyūga and Bungo. The Shimazu fought well, but had few firearms and lacked discipline and training; they were steadily overwhelmed through the superior quality and quantity. By the end of May 1587, the various island daimyos had turned to Hideyoshi's side. In June, Shimazu was routed in Satsuma itself. Yoshihisa sued for peace, and a truce was agreed. Hideyoshi offered generous terms for a lasting peace to Iehisa's and Yoshihiro's son; though Yoshihisa initially refused the offer, Hideyoshi tried again and was this time successful.
After Surrender
Most of the domains Yoshihisa had conquered were given by Hideyoshi to three of his senior generals - Kato, Konishi, and Kuroda - and the Shimazu clan managed to retain only Satsuma Province and Ōsumi Province, as well as half of Hyuga. The Mori were given fiefs in northern Kyushu, and Kobayakawa gained Chikuzen. Yoshihisa shaved his head to surrender, showing that he would become a Buddhist monk if his life was spared. His name as a monk was Ryūhaku but it is unclear whether he retired in order to allow Yoshihiro to rule. As a retainer under Hideyoshi, his younger brother Yoshihiro controlled troops, but it is believed that Yoshihisa still managed day-to-day affairs in the domain. Yoshihisa did not have a son to succeed him, so he had Yoshihiro's son, Shimazu Tadatsune marry the third daughter Kameju and adopted him as the successor. After his domain was split up by Hideyoshi, Tokugawa Ieyasu invited Yoshihisa to Fushimi Castle. Ieyasu and his retainers repeatedly asked Yoshihisa how he managed to unify Kyushu; eventually, Yoshihisa relented, saying that he won his victories through his retainers - " my three younger brothers, led by Yoshihiro, as well as retainers like Uwai Satokane and Yamada Arinobu, fought so well united under the same goal, I never had a chance to show bravery in a battle. I only had to wait in the Kagoshima Castle for news brought by messengers of their victories." After Yoshihisa left, Ieyasu told his retainers that " a general let retainers under him work to the best of their abilities. This is how a great general should be."
Death
In 1611, he died of illness. Posthumously, he was named 貫明存忠庵主. He was buried at what had once been the site of Fukushoji in Kagoshima - his tombstone remains, along with those of the other leaders of his clan. There are also monuments built in his memory at Kokubun, Ima Kumano Kannonji in Kyoto, and Koyasan. Though there is no portrait of Yoshihisa remaining, there is a bronze figure of Yoshihisa at the Taiheiji, depicting his surrender to Hideyoshi. The statue was produced after he died.
