Lifespan: 1520 (?) to 1/11 of Eiroku 7 (1564)
Rank: sengoku daimyō
Titles: Lieutenant of the Left Division of Outer Palace Guards, Assistant Director of the Bureau of Palace Maintenance, Governor of Mimasaka
Father: Uragami Muramune
Siblings: Masamune, Munekage
Children: Tadamune, Kiyomune, Narimune
Uragami Masamune served as sengoku daimyō of Bizen Province. He was the eldest son of Uragami Muramune and brother of Uragami Munekage.
In 1531, Masamune became head of the clan at age eleven after his father died in battle at Tennō Castle in Settsu. Given Masamune’s young age, Uragami Kunihide served as his mentor until 1538. In the early years, he fiercely opposed his late father’s enemy, Akamatsu Harumasa, joining with the kunishū from western Harima to pursue the fight. An invasion into the Sanyō Region by Amago Akihisa prompted Masamune to reconcile with Harumasa. Nevertheless, disaffection by the kunishū led to a loss, compelling Masamune to withdraw from Bingo to Harima Province. Late in 1539, Masamune was driven out of Harima by Amago forces advancing from the east. Under the direction of Harumasa, he fled via Awaji to Sakai in Izumi Province. In 1540, Masamune received one of the characters in his name from Harumasa.
Masamune waited until Akihisa withdrew his occupying forces from Harima after the Battle of Yoshida-Kōriyama in 1542, after which he and Harumasa returned to Harima with the support of the bakufu. He made progress in restoring his influence in Harima and Bizen until 1544. During this period, Masamune provided overall direction to the Akamatsu retainers, and, thereafter, served as the leading elder for Harumasa. Jointly with Harumasa’s bugyō, Masamune issued written directives from the Akamatsu clan. Acting on his own, Masamune collaborated with the Matsuda and Saisho clans. From Muroyama Castle in Murotsu, he further expanded his influence in Bizen and Harima, beyond the confines of a retainer of the Akamatsu.
In 1551, Masamune had a difference of opinion with his younger brother, Munekage, in regard to a second invasion by Amago Haruhisa into Bizen. Masamune entered into an alliance with Haruhisa and Matsuda Mototeru, while Munekage opposed them with the support of Mōri Motonari. Kunishū in Bizen variously aligned themselves with each side – Ukita Kunisada joined with Masamune whereas Nakayama Nobumasa aligned with Munekage, leading to a showdown for control of the province. Masamune lost Tenjinyama and Shinjōyama castles in succession. His former lord, Harumasa, sent forces to Mitsui Castle while Masamune found himself increasingly surrounded by enemy forces. During the period from 1555 to 1557, Masamune could no longer control the movements of the kunishū and lost a significant amount of his territory in Bizen.
Masamune pleaded with Haruhisa for support. Haruhisa responded by personally leading a force of 30,000 men to attack Munekage in Mimasaka Province, but could not achieve a definitive victory. Haruhisa’s subsequent death led to a decline of the Amago influence, so that Munekage could no longer count on their support.
In a vulnerable position, Masamune sought help from Ashikaga Yoshiteru in 1558 to broker a peace with the Mōri. Then, in a bid to restore his power, Masamune deposed Akamatsu Harumasa and compelled Harumasa’s son, Akamatsu Yoshisuke, to become the successor. However, Harumasa relied upon Akamatsu Masahide, his son-in-law and lord of Tatsuno Castle, promoting the independence of the Tatsuno branch of the clan and thereby igniting another conflict.
After more than ten years of confrontation, in 1563, Masamune finally reached a settlement with Munekage. He joined with Kuroda Mototaka from Harima to regain power, but, early in 1564, during the wedding ceremony between Mototaka’s daughter and Uragami Kiyomune’s son at Murotsu Castle, or in that same evening, Akamatsu Masahide launched a surprise attack and killed both Masamune and Munekage.