Mori Tadamasa (1570 - July 31, 1634) was a notable military commander during Japan’s Warring States period and an early Edo-period daimyo. Initially, he governed Kawanakajima Domain in Shinano Province (modern-day Nagano Prefecture) and later became the first lord of Tsuyama Domain in Mimasaka Province (now northern Okayama Prefecture). He founded the Mori family line of the Ako Domain. Tadamasa’s family origins trace back to the Genji (Minamoto) clan, specifically the Kawachi-Genji branch from Kawachi Province (in present-day southeastern Osaka Prefecture), a lineage tied to Emperor Seiwa through his ancestor Yorisada Mori, a great-grandson of the famed Minamoto no Yoshiie.
In 1582, Tadamasa entered the service of Oda Nobunaga as a page but was soon dismissed after a scuffle with a fellow page, with Nobunaga deeming him too young for the position. This dismissal inadvertently spared Tadamasa from involvement in the Honno-ji Incident, where Nobunaga was assassinated. Two years later, in 1584, his older brother Nagayoshi was killed at the Battle of Komaki and Nagakute, and with his other brothers also deceased, Tadamasa inherited the Mori family estate. He was granted a 70,000-koku fief in Mino Province (southern Gifu Prefecture), residing at Kaneyama Castle. In 1587, Toyotomi Hideyoshi awarded him the surname Hashiba, and he was thereafter known as Hashiba Kaneyama Jiju (chamberlain).
During Hideyoshi’s Korean invasions, Tadamasa served as a public works administrator at Nagoya Castle in Kyushu, leading 2,000 troops. Following Hideyoshi’s death, Tadamasa allied with Tokugawa Ieyasu and received the Matsushiro Domain in Shinano Province (valued at 137,000 koku) in 1600. In the same year, he joined Tokugawa’s Hidetada Eastern Army at the Battle of Sekigahara, participating in the siege of Ueda Castle, home of Sanada Masayuki of the Western Army. Tadamasa resumed the Mori surname after the battle and was rewarded with the Tsuyama Domain (180,000 koku) for his service, becoming its first lord.
Tadamasa passed away in 1634, reportedly after developing severe stomach pain following the consumption of a peach, likely due to food poisoning. He was interred at Sangen-in, a sub-temple of Daitoku-ji in Kyoto’s Murasakino, which is also associated with the family of Ishida Mitsunari.
See also
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Yamagata Masakage
Masakage was one of Takeda Shingen’s most loyal and capable commanders. He was included in the famous list of the “Twenty-Four Generals of Takeda Shingen” and also belonged to the inner circle of four especially trusted warlords known as the Shitennō.
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Yagyu Munenori
Yagyū Munenori began his service under Tokugawa Ieyasu while his father, Yagyū Muneyoshi, was still at his side. In 1600, Munenori took part in the decisive Battle of Sekigahara. As early as 1601, he was appointed a kenjutsu instructor to Tokugawa Hidetada, Ieyasu’s son, who later became the second shogun of the Tokugawa clan.
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Yagyu Muneyoshi
A samurai from Yamato Province, he was born into a family that had been defeated in its struggle against the Tsutsui clan. Muneyoshi first took part in battle at the age of sixteen. Due to circumstances beyond his control, he was forced to enter the service of the Tsutsui house and later served Miyoshi Tōkei. He subsequently came under the command of Matsunaga Hisahide and in time became a vassal first of Oda and later of Toyotomi.
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Endo Naozune
Naozune served under Azai Nagamasa and was one of the clan’s leading vassals, renowned for his bravery and determination. He accompanied Nagamasa during his first meeting with Oda Nobunaga and at that time asked for permission to kill Nobunaga, fearing him as an extremely dangerous man; however, Nagamasa did not grant this request.
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Hosokawa Sumimoto
Sumimoto came from the Hosokawa clan: he was the biological son of Hosokawa Yoshiharu and at the same time the adopted son of Hosokawa Masamoto, the heir of Hosokawa Katsumoto, one of the principal instigators of the Ōnin War. Masamoto was homosexual, never married, and had no children of his own. At first he adopted Sumiyuki, a scion of the aristocratic Kujō family, but this choice provoked dissatisfaction and sharp criticism from the senior vassals of the Hosokawa house. As a result, Masamoto changed his decision and proclaimed Sumimoto as his heir, a representative of a collateral branch of the Hosokawa clan that had long been based in Awa Province on the island of Shikoku. Almost immediately after this, the boy became entangled in a complex and bitter web of political intrigue.
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Honda Masanobu
Masanobu initially belonged to the retinue of Tokugawa Ieyasu, but later entered the service of Sakai Shōgen, a daimyo and priest from Ueno. This shift automatically made him an enemy of Ieyasu, who was engaged in conflict with the Ikkō-ikki movement in Mikawa Province. After the Ikkō-ikki were defeated in 1564, Masanobu was forced to flee, but in time he returned and once again entered Ieyasu’s service. He did not gain fame as a military commander due to a wound sustained in his youth; nevertheless, over the following fifty years he consistently remained loyal to Ieyasu.
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Honda Masazumi
Masazumi was the eldest son of Honda Masanobu. From a young age, he served Tokugawa Ieyasu alongside his father, taking part in the affairs of the Tokugawa house and gradually gaining experience in both military and administrative matters. At the decisive Battle of Sekigahara in 1600, Masazumi was part of the core Tokugawa forces, a clear sign of the high level of trust Ieyasu placed in him. After the campaign ended, he was given a highly sensitive assignment—serving in the guard of the defeated Ishida Mitsunari, one of Tokugawa’s principal enemies—an obligation that required exceptional reliability and caution.
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Hojo Shigetoki
Hōjō Shigetoki, the third son of Hōjō Yoshitoki, was still very young—only five years old—when his grandfather Tokimasa became the first member of the Hōjō clan to assume the position of shogunal regent.
