He served the Tokugawa clan along with his father Tadayo, who was the bodyguard of the seii taishogun (literally, "great general who subdues the barbarians") Hidetada TOKUGAWA, and joined his first battle in October 1614 at the Osaka Fuyu no Jin (Winter Siege of Osaka, also known as the Siege of Osaka).
征夷大将軍徳川秀忠付きの父・忠世とともに徳川氏に仕え、慶長19年（1614年）10月の大坂冬の陣（大坂の役）で初陣。