Tadamasa was the eldest son of [[Sakikabara Yasumasa]]. His grandfather on his mother's side, [[Oosuga Yasutaka]] [大須賀康高], had no sons of his own and so Tadamasa was adopted by him to carry on the Oosuga name. Yasutaka died in [[1589]] and Yasumasa succeeded him, also being given the use of the name 'Matsudaira' [松平] by Tokugawa Ieyasu. When the Tokugawa house was relocated to the [[Kanto]] following [[1590]] the young Yasutaka was established in [[Kazusa province|Kazusa Province]] with a 30,000-koku fief. In 1601 his fief was moved to Tôtômi and increased to 60,000 koku. He fell ill in 1607 and died in Kyoto in the 9th month.
+
Tadamasa was the eldest son of [[Sakikabara Yasumasa]]. His grandfather on his mother's side, [[Oosuga Yasutaka]] [大須賀康高], had no sons of his own and so Tadamasa was adopted by him to carry on the Oosuga name. Yasutaka died in [[1589]] and Yasumasa succeeded him, also being given the use of the name 'Matsudaira' [松平] by [[Tokugawa Ieyasu]]. When the Tokugawa house was relocated to the [[Kanto]] following [[1590]] the young Yasutaka was established in [[Kazusa province|Kazusa Province]] with a 30,000-koku fief. In 1601 his fief was moved to [[Totomi province|Tôtômi]] and increased to 60,000 koku. He fell ill in 1607 and died in Kyoto in the 9th month.