Lifespan: Tenbun 9 (1540) to 5/13 of Keichō 14 (1609)
Title: Vice Minister of Military Affairs, Governor of Aki
Lord: Shimazu clan
Father: Kabayama Yoshihisa
Mother: Osumi (second daughter of Shimazu Tadayoshi)
Siblings: Tadasoe, Tadasuke, sister (wife of Shimazu Iehisa)
Wife: Daughter of Murata Tsunesada
Children: Norihisa, Hisataka
Kabayama Tadasuke served as a bushō from the Sengoku to early Edo periods. He enjoyed waka, or classical Japanese poetry, and was also skilled in the sport of dog shooting known as inuōmono popular in Kyūshū. In this event, the participants rode on horses in a large ring while shooting dogs with blunt-head arrows to score points.
The Kabayama were an illegitimate branch of the Shimazu clan. The Kabayama were founded by Shimazu Sukehisa, the fifth son of Shimazu Tadamune, the fourth head of the Shimazu who served as the military governors of Satsuma Province. Sukehisa first acquired landholdings in Kabayama, Hayamizu, and Terabashira in the Mimata-in manor in Hyūga Province.
In 1540, Tadasuke was born as the son of Kabayama Yoshihisa.
In 1573, after surrendering to the Shimazu clan, Nejime Shigetake of Ōsumi Province was attacked by the Kimotsuki clan. In an effort to assist Shigetake, Tadasuke deployed and then defeated the Kimotsuki forces at Nishimata.
In 1575, during an inuōmono event, Tadasuke, participating as a mounted archer, was able to shoot a total of eleven dogs. Owing to his demonstration of skill, he was invited to the event every year. In 1576, he participated as an archer in an event held to entertain an emissary from the Ryūkyū islands. That same year, Tadasuke deployed for an assault against the Itō clan at Takaharu Castle. Thereafter, he was nominated as the lord of Mukasa in Hyūga Province. However, around the time of the Battle of Mimikawa in 1578, he assigned Mukasa to his designated heir, Norihisa, while he resided in Kenri in Ōsumi Province.
In 1586, Tadasuke participated in the Siege of Iwaya Castle defended by Takahashi Jōun. Despite having his helmet smashed by a large rock and suffering numerous wounds from arrows and gunshot, he fought valiantly, finally toppling the castle, but during the withdrawal, fell ill and returned to Kenri. After convalescing for several months, Tadasuke returned to make contributions during an invasion of Bungo Province.
In 1609, Tadasuke died of illness in Izumi in Satsuma Province.
Tadasuke’s younger sister was married to Shimazu Iehisa, so he accompanied Iehisa in many contests including the Battle of Hetsugigawa. One account notes that for Shimazu Yoshihiro to act jealously toward Iehisa’s military achievements was not becoming of a commanding general, suggesting a degree of discord among the four Shimazu siblings of that generation.