Born in 1567 as the second son of the Shinano warlord Sanada Masayuki. His given name was Nobushige; "Yukimura" is a later appellation. He spent years as a hostage in Toyotomi Hideyoshi's service, gaining firsthand knowledge of central politics and warfare, and married the daughter of Otani Yoshitsugu. At the Battle of Sekigahara in 1600, he and his father joined the Western army and, with a small force at Ueda Castle, held Tokugawa Hidetada's army of over 20,000 at bay, preventing it from reaching Sekigahara in time. After defeat, he was confined to Kudoyama in Kishu for 14 years. In the Winter Siege of Osaka (1614) he joined the Toyotomi defenders and built the famous crescent-shaped "Sanada-maru" outwork on the southern face of the castle, inflicting severe casualties on the Tokugawa forces. At the Summer Siege (1615), he fought at Tennoji and charged Ieyasu's headquarters three times—tradition holds that Ieyasu himself prepared to commit suicide before the assault was finally repulsed. Yukimura died in battle, and Satsuma warrior Nishio Muneji praised him as "the greatest warrior in Japan—a hero unmatched in all the old tales." He was 49.