Lifespan: Tenbun 6 (1537) to 9/27 of Keichō 18 (1613)
Other Names: Yahachirō (childhood), Jiemon
Rank: bushō, daimyō
Lord: Matsudaira Hirotada → Tokugawa Ieyasu → Tokugawa Hidetada
Father: Ōkubo Tadakazu
Siblings: Tadayo, Tadasuke, Tadakane, Tadayori, Tadakaku, Tadatame, Tadanaga, Tadanori, Tadamoto
Children: Takemaru, Tadakane, daughter (wife of Kyūbei), daughter (wife of Honma Heibei), daughter (formal wife of Aoyama Tadatoshi), daughter (wife of Hattori Motonobu)
Adopted Children: Daughter (formal wife of Takagi Masatsugu)
Ōkubo Tadasuke served as a bushō and daimyō from the Sengoku to early Edo periods. In the Edo period, he served as the lord of the Numazu domain in Suruga Province. Tadasuke is included among the Seven Spears of Kanie and the Sixteen Divine Generals of the Tokugawa.
In 1537, Tadasuke was born as the second son of Ōkubo Tadakazu, a retainer of the Tokugawa in Kamiwada in Mikawa Province. Together with his father and older brother, Ōkubo Tadayo, he served Matsudaira Hirotada and Tokugawa Ieyasu. Brave and skilled in the military arts, in 1572, at the Battle of Hitokotozaka, Tadasuke joined Honda Tadakatsu to serve as the rear guard. He contributed meritoriousy in the Battle of Nagashino in 1575 and the Battle of Komaki-Nagakute in 1584.
In 1590, after Ieyasu moved to the Kantō, Tadasuke was awarded a fief of 5,000 koku in Mobara in Kazusa Province. In 1600, at the Battle of Sekigahara, he served for the Eastern Army under the command of Tokugawa Hidetada but was blunted by Sanada Masayuki and Sanada Nobushige (father and son). In 1601, Tadasuke was granted 20,000 koku in Numazu in Suruga Province, becoming a daimyō. He was based at Numazu Castle (Sanmaibashi Castle).
Tadasuke had two sons, Ōkubo Tadakane and Takemaru, but both died early so he adopted his younger brother, Ōkubo Tadanori (who at the time was a hatamoto serving as a direct retainer of the Edo bakufu) and attempted to transfer the family to him, but Tadanori firmly refused on the grounds that the inheritance had not been attained through his own merit. On 9/27 of Keichō 18 (1613), Tadasuke died at the age of seventy-seven. In the absence of an heir, the Numazu domain came to an end and the family removed from its position.
At the Battle of Nagashino, Oda Nobunaga praised Tadasuke and his older brother, Tadayo, for their valor by referring to them as plaster, meaning that they would stick to the enemy and not let go.
Similar to another retainer, Honda Tadakatsu, Tadasuke avoided injury throughout his life despite participating in many battles.