
Nagamori possessed remarkable diplomatic and administrative talent while remaining a brave warrior. He is believed to have come from the village of Mashita in the province of Owari, which today is part of Aichi Prefecture. He was a vassal of Oda Nobunaga and later served Toyotomi Hideyoshi. In the Battle of Komaki–Nagakute in 1584, Nagamori took at least two enemy heads. Later, he was entrusted with overseeing major public construction projects, including the reconstruction of Fushimi Castle and the building of the large Sanjō and Gojō bridges in Kyoto.
In 1585, Hideyoshi received the title of kampaku — imperial regent — and created the “Council of Five Commissioners” (go-bugyō) to manage state affairs. Mashita Nagamori became one of the go-bugyō, alongside Ishida Mitsunari, Asano Nagamasa, Natsuka Masaie, and Maeda Gen’i. Nagamori’s diplomatic skills were demonstrated in negotiations with Uesugi Kagekatsu, who eventually agreed to visit Hideyoshi in Kyoto. During the Odawara campaign against the Hōjō clan, it was Nagamori’s efforts that secured the loyalty of daimyō Date Masamune.
Carrying out Hideyoshi’s land reform project, Nagamori conducted cadastral surveys in the provinces of Ōmi in 1591 and Awa and Hitachi in 1595. Thanks to his success in this undertaking, he received possession of Koriyama Castle in Yamato Province, along with extensive lands yielding an income of 200,000 koku of rice. As one of the go-bugyō, Nagamori also took part in Hideyoshi’s invasion of Korea in 1592.
After Hideyoshi’s death, as the struggle for power erupted between Ishida Mitsunari and Tokugawa Ieyasu, it appeared that Nagamori was hesitant in choosing a side. Ieyasu personally visited him, attempting to persuade him to join the Eastern coalition. However, when the Sekigahara campaign began in 1600, Nagamori, together with Mōri Terumoto, the nominal leader of the Western coalition, chose to take refuge in Osaka Castle in order to protect Hideyoshi’s heir, Toyotomi Hideyori.
One theory suggests that despite formally joining the Western coalition, Nagamori was secretly providing Ieyasu with information on troop movements. This is regarded as the reason why, after the Eastern coalition’s victory, Ieyasu spared Nagamori’s life. Even so, he stripped him of his lands and titles and sent him to Iwatsuki Castle to serve Koriki Kiyonaga, a vassal of the Tokugawa clan.
During the Winter Campaign of Osaka in 1614, Nagamori received orders to spy on Hideyori’s supporters on behalf of the Tokugawa shogunate. This may have been the cause of the tragic events that followed a year later.
During the Summer Campaign of Osaka in 1615, Nagamori’s son, Mashita Moritsugu, was in the service of Ieyasu’s son, Tokugawa Yoshinao. However, he fled and joined the defenders of Osaka Castle. Scholars still debate the reasons for his actions: some believe Moritsugu was angered by his father’s “betrayal” during the Winter Campaign and sought to “restore the family’s honor,” while others argue that he had been sent into the castle as a spy and supposedly had Yoshinao’s approval. In any case, the events that followed indicate that Tokugawa Ieyasu was extremely displeased with Moritsugu’s actions. He ordered the 71-year-old Mashita Nagamori to commit seppuku. Moritsugu himself was killed in the battle for the castle. Nagamori was buried at Anrakuji Temple in Saitama Prefecture.
See also
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Takeda Nobuyoshi

Takeda Nobuyoshi (1128–1186 or later) was a prominent Japanese samurai lord of the late Heian and early Kamakura periods and the founder of the Takeda clan.
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Tokugawa Iemochi

Tokugawa Iemochi (1846–1866) was the fourteenth shōgun of the Tokugawa shogunate and ruled from 1858 until his death. His reign came during the turbulent final years of the shogunate, when Japan faced growing Western pressure and serious internal political conflict.
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Tokugawa Ienari

Tokugawa Ienari (1773–1841) was the eleventh shōgun of the Tokugawa shogunate and ruled from 1787 to 1837, making him the longest-serving Tokugawa shōgun. He was a great-grandson of the eighth shōgun, Tokugawa Yoshimune.
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Matsudaira Nobuyasu

Matsudaira Nobuyasu was only twenty years old when his father ordered him to commit seppuku. The reason was not a defeat in battle, but a crisis inside the Tokugawa family that had become too dangerous to ignore.
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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.
