Yasumasa was the second son of Sakakibara Nagamasa and was born in Ueno in Mikawa Province. From a young age, he began serving Tokugawa Ieyasu and eventually rose to the position of one of his most trusted generals. His wife was the daughter of Osuga Yasutaka. Ieyasu first noticed the young Yasumasa during the suppression of the Ikkō-ikki uprising in Mikawa in 1564. Thanks to his demonstrated abilities, Yasumasa was granted the privilege of using the character “yasu”—the second character of Ieyasu’s own name—in his own. Although he was the second child in his family, he became his father’s heir, though the exact reasons for this remain unknown.
Yasumasa came of age in 1566, and at that time he and Honda Tadakatsu were admitted into Ieyasu’s personal guard, the hatamoto. Each of them was entrusted with command over a unit of fifty horsemen. In the Battle of Anegawa in 1570, Yasumasa made a significant contribution to the victory: together with Honda Tadakatsu, he struck the flank of the Asai forces. In the Battle of Nagashino in 1575, he helped defeat the troops of Naitō Masatoyo. He also fought in the Battle of Mikatagahara in 1573 and took part in the capture of Takatenjin Castle.
Yasumasa stood by Ieyasu when he decided to confront Toyotomi Hideyoshi, and it was Yasumasa who proposed using Komaki as the campaign headquarters. In 1586, he accompanied Ieyasu to negotiations with Hideyoshi in Osaka and in the same year received the title of Shikibu-tayū. He also took part in the Odawara campaign in 1590.
After Ieyasu relocated to the Kantō region, Yasumasa was granted Tatebayashi Castle and appointed head of the group responsible for the allocation of landholdings. While Ieyasu was in Kyushu during Hideyoshi’s Korean invasions (1592–1593, 1597–1598), Yasumasa served as one of the main administrators of the Kantō region as well as an advisor to Tokugawa Hidetada.
During the Sekigahara campaign of 1600, Yasumasa was attached to Tokugawa Hidetada’s army and took part in the siege of Ueda Castle in Shinano Province. After the Tokugawa victory, he was granted lands in Kōzuke Province with an income of 100,000 koku of rice.
Yasumasa died in the fifth month of 1606, and his third son, Yasukatsu, succeeded him. The Sakakibara clan remained one of the most loyal houses to the Tokugawa government throughout the entire Edo period.
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.
