Battles had raged for the previous few years between the daimyō of Kyūshū, and by 1587 the Shimazu family of Satsuma were the primary power on the island. In 1586, they heard of Hideyoshi's plans for invasion, and lifted their siege ofTachibana castle, withdrawing a great portion of their forces back to Higo province, while the rest stayed in Bungo province. There, they seized Funai Castle from the Ōtomo clan and prepared for the invasion. The Ōtomo were supported by armies under Sengoku Hidehisa, Chōsokabe Motochika and Sogō Masayasu, a major Shikoku lord who had been defeated by Hideyoshi the previous year, and had thus joined him. Though Bungo province ultimately fell to the Shimazu. Sengoku and Chōsokabe delayed them, however, and weakened them in preparation for the arrival of Hideyoshi's armies and those of the Mōri clan, another ally of Hideyoshi. Hashiba Hidenaga, half-brother to Hideyoshi, landed to the south of Bungo, attacking the Shimazu at Takajō, on Kyūshū's eastern coast, in 1587. Meanwhile, Hideyoshi took his own forces down a more westerly route, attacking Ganjaku Castle in Chikuzen province, which was held by the Akizuki clan. Later that year, the two brothers would meet up in the Shimazu's home province of Satsuma, to assault their home castle at Kagoshima. Ultimately, Kagoshima itself was not attacked; the Shimazu surrendered, leaving Hideyoshi to return his attention to the Hōjō clan of the Kantō, the last major clan to oppose him. Hideyoshi would make use of Kyūshū through much of the 1590s in his attacks on Korea.
Battles of the Kyūshū campaign
1586
Siege of Toshimitsu - the Shimazu seize Toshimitsu and Funai Castles from the Ōtomo, despite delaying tactics from Hideyoshi's allies. Myorin defended Tsurusaki castle and stop Shimazu advance.
Battle of Hetsugigawa - Sengoku, Ōtomo, and Chōsokabe continue to battle and delay the Shimazu, but ultimately retreat, leaving Bungo province to the Shimazu.
1587
Battle of Takajō - Hashiba Hidenaga attacks the Shimazu in Hyūga province, forcing them to retreat to Satsuma.
Siege of Ganjaku - Toyotomi Hideyoshi attacks the Akizuki clan in the north of Kyūshū.
Siege of Akizuki - Hideyoshi continues his assault on the Akizuki by sieging Oguma castle; the Akizuki surrender.
Battle of Sendaigawa - Hideyoshi and Hidenaga join forces and begin their attack on Satsuma.
Siege of Kagoshima - Hideyoshi and Hidenaga surround the Shimazu capital, and earn a surrender without laying siege to the castle.