Lifespan: Kōji 1 (1555) to 3/14 of Keichō 20 (1615)
Other Names: Kuhachirō (childhood), Sadamasa
Rank: bushō, daimyō
Title: Junior Fifth Rank (Lower), Governor of Mimasaka
Domain: Kōzuke-Obata → Mino-Kanō
Lord: Tokugawa Ieyasu → Takeda Shingen → Takeda Katsuyori → Tokugawa Ieyasu → Tokugawa Hidetada
Father: Okudaira Sadayoshi
Mother: Kamehime (eldest daughter of Tokugawa Ieyasu)
Siblings: Nobumasa, Masakatsu
Wife: [Formal] Kamehime (eldest daughter of Tokugawa Ieyasu)
Children: Iemasa, Matsudaira Ieharu, Tadamasa, Matsudaira Tadaakira, daughter (wife of Ōkubo Tadatsune)
Okudaira Nobumasa served as a bushō and daimyō from the Sengoku to early Edo periods. He had alternating periods of service for rival clans – the Tokugawa and the Takeda.
In the Edo period, Nobumasa (first known as Sadamasa) was the first lord of the Kōzuke-Obata domain and, later, the first lord of the Mino-Kanō domain. Nobumasa wed as his formal wife the eldest daughter of Tokugawa Ieyasu, Kamehime, and, as Ieyasu’s son-in-law, performed important roles for the Tokugawa clan. Throughout his life, Nobumasa did not keep any consorts while Kamehime bore four sons (Okudaira Iemasa, Matsudaira Ieharu, Okudaira Tadamasa, and Matsudaira Tadaakira) and one daughter (the wife of Ōkubo Tadatsune).
Nobumasa was born as the eldest son of Okudaira Sadayoshi, a powerful kokujin, or provincial landowner, in Tsukude in Mikawa Province. His mother was the daughter of Makino Shigetane.
The Okudaira clan, until the era of his grandfather, Okudaira Sadakatsu, was affiliated with the Imagawa clan. After the defeat of the Imagawa at the Battle of Okehazama in the fifth month of 1560, their influence in Mikawa declined so Nobumasa came under the command of Tokugawa Ieyasu and joined in an assault on Kakegawa Castle in the Sano DIstrict of Tōtōmi Province. From 1570 to 1573, during the invasion of Mikawa by Takeda Shingen, he affiliated with the Takeda clan.
Meanwhile, around 1573, Ieyasu considered engaging the Okudaira, a powerful band of bushi, in Okumikawa (the mountainous areas in the northeast portion of Mikawa) to contain the influence of the Takeda clan. He sent a messenger to the Okudaira but Okudaira Sadayoshi only responded with the message: “Thank you for your kindness.” Ieyasu then consulted with Oda Nobunaga who advised that Ieyasu’s eldest daughter, Kamehime, should wed Sadayoshi’s eldest son, Okudaira Sadamasa (Nobumasa). Ieyasu acknowledged Nobunaga’s input and proposed to Sadayoshi the following: (1) the engagement of Kamehime and Sadamasa, (2) an increase to the territory held by the Okudaira, and (3) the marriage of Sadayoshi’s daughter to Honda Shigezumi (the second son of Honda Hirotaka). On 6/22 of Genki 4 (1573), Sadayoshi responded to Ieyasu with the following: (1) the death of Takeda Shingen has been confirmed, and (2) a desire for Sadayoshi and Sadamasa (father and son) to serve the Tokugawa.
Upon proposing to Sadamasa an engagement to Kamehime, he divorced his wife, Ofū, who was a hostage of the Takeda family. This served as evidence that Sadamasa had forsaken the Takeda in favor of the Tokugawa. To make a lesson of her, on 9/21 of Tenshō 1 (1573), Ofū was crucified at the age of sixteen by Yamagata Masakage. In addition to Ofū, Sadamasa’s younger brother, Senmaru (age thirteen) and one other member of the Okudaira were sacrificed. After a while, Sadamasa became a retainer of the Tokugawa.
In 1575, he built Shinshiro Castle in Mikawa to defend against the Takeda clan.
Battle of Nagashino
Upset at the defection by the Okudaira clan, in the fifth month of 1575, Takeda Katsuyori led an army of 15,000 soldiers and pressed toward Nagashino Castle. Sadamasa holed-up in Nagashino Castle and had his retainer, Torii Sune-emon urgently request reinforcements. He withstood the assaults from the Takeda army until the siege was finally broken by a detached division of allied forces from the Oda and Tokugawa led by Sakai Tadatsugu. As a result, on 5/21, at the Battle of Nagashino, the allied forces of the Oda and Tokugawa defeated the Takeda army.
Nobumasa was praised by Nobunaga for his service in battle. After receiving one of the characters from the name of Nobunaga, he changed his name from Sadamasa to Nobumasa. Individuals who received a character in their name from Nobunaga other than direct retainers included Chōsokabe Nobuchika and Matsudaira Nobuyasu, but it is surmised these were instances of diplomatic courtesy. There is also a theory, however, that the character “Nobu” originated from Harunobu (the name of Takeda Shingen) and, in later eras, had scruples over the circumstances and fabricated the story that the character was conferred by Nobunaga.
Ieyasu praised Nobumasa and gave him a precious sword crafted by Daihannya Nagamitsu of Bizen Province during the Kamakura period. Moreover, he commended each one of twelve senior retainers of the Okudaira who supported Nobumasa during the siege. Further, he provided sealed documents with promises including a guarantee of the fiefs of each of these retainers for their children and grandchildren. After the war, Nobumasa’s father, Sadayoshi, formally transferred the headship of the clan to him.
In 1582, during the Tenshō Jingo Conflict, Nobumasa joined Sakai Tadatsugu to invade the territory of the Takeda family. In 1585, Ishikawa Kazumasa, a veteran of the Tokugawa clan, absconded to Toyotomi Hideyoshi. To respond to the leaking of his family’s military secrets by Kazumasa to Hideyoshi, Ieyasu rapidly changed the military system from one deployed in Mikawa to the system of Takeda Shingen. Having formerly served under this system as a retainer of the Takeda, Nobumasa contributed to the transformation.
In the seventh month of 1590, Nobumasa followed when Ieyasu was transferred to the Kantō. On 8/23 of Tenshō 18 (1590), he entered a domain of 30,000 koku in Miyazaki in the Kanra District of Kōzuke.
In the ninth month of 1600, Nobumasa participated in the main Battle of Sekigahara. In the family records and those of the Nakatsu domain, there are references to his affiliation with Hidetada’s army. After the war, he served until the next year as the Kyōto shoshidai, or official of the bakufu in charge of security in the capital. During this time, he apprehended Ankokuji Ekei who was in hiding in Kyōto. Nobumasa gave to Ieyasu as a present a precious short sword made by Okazaki Masamune during the Kamakura period that was owned by Ekei, but this was later given back to Nobumasa. Today this is designated a national treasure. Meanwhile, Ukita Hideie who was in hiding in Uzumasa, escaped and went for protection under Shimazu Yoshihiro in Satsuma Province.
In the third month of 1601, based on a series of contributions at the Battle of Sekigahara, Nobumasa’s fief was increased from 30,000 koku in Obata in Kōzuke Province to 100,000 koku in Kanō in Mino Province. In 1602, he retired in Kanō and transferred his seat as lord of the domain to his third son, Okudaira Tadamasa.
In 1614, Nobumasa took the lead ahead of Tadamasa and his eldest son, Okudaira Iemasa (possessing a fief of 100,000 koku in Utsunomiya in Shimotsuke Province), but perhaps out of concern for his advanced age, he was exempted from service at the Winter Campaign of the Siege of Ōsaka and his sons went in his place. He then dispatched troops from Mino-Kanō domain to serve under his younger son, Matsudaira Tadaakira, who served in his only battle.
Nobumasa died in the third month of 1615.
In remembrance of Nobumasa’s valor to hold-out at Nagashino Castle against Takeda Katsuyori during the Battle of Nagashino, in the fifth month of every year, a festival known as the Tainishisai is held at the Okudaira Shrine in the city of Nakatsu in the northwestern part of Ōita Prefecture.