Shimazu Yoshihiro
Tadatsune was the third son of Shimazu Yoshihiro. Since Yoshihiro's elder brother, Shimazu Yoshihisa, did not have a son and his other elder brother, Shimazu Hisakazu, had died of illness in Korea, he was deemed successor to their uncle and he later took the name of "Iehisa" (家久). Like his father and uncle, he was known for bravery on the battlefield. During the second half of Hideyoshi's invasions of Korea, fighting beside his father, he helped drive off the Ming army of over 100,000 men with only 8000 men. As head of the Shimazu clan, he sought to remove corrupt or disloyal counselors, and to reform the clan leadership. To this end, in 1599, he killed a long-time retainer and "karō", Ijuin Tadamune, as well as his son, Ijuin Tadazane, when they tried to part with the Shimazu clan.