In 1574 his troops marched on to Mino (Gifu Prefecture) and conquered 18 castles belonging to Nobunaga Oda. The following year he laid seige to Nagashino, a castle in Higashi Mikawa (Aichi Prefecture), and gave battle to the combined armies of Ieyasu Tokugawa and Nobunaga and suffered a crushing defeat. Thereupon to secure the assistance of Ujimasa Hojo, Katsuyori married Ujimasa's sister.
In 1577 he was once more at war over the question of succession following the death of Kenshin Uesugi. His army marched into Suruga (Shizuoka Prefecture) but he was once again defeated by the combined armies of Ujimasa and Ieyasu and had to return to Kai (Yamanashi Prefecture), a disappointed man.
In 1581 he built a castle at Hemmi, naming it Shimpu, the New Capital. His enemies, however, were still after him and in 1852 he was taken by surprise by the armies of Ujimasa Hoj o and Ieyasu. With the fall of the Takato Castle the persecuted man tried to find shelter with Nobushige Oyamada, but was refused and he therefore had to retreat further to Mount Tem-moku. But here, too, he found no peace as the army of Kazumasu Takigawa soon surrounded the mountain fortress.
Realizing that there was 110 hope left now, the defeated warrior committed suicide together with his wife and son. Thus with his death ended the House of Takedas in 1582.
Katsuyori Takeda was considered brave and fearless but imprudent and impulsive. Because of this his followers left him one by one. He was driven with his father's ambitions to live in Kyoto and become head of the various clans there. With the assistance of the Uesugi and Hojo clans and his close contact with ex-Shogun Yoshiaki Ashikaga and the Lord of Aki he set forth to complete his ambition.
Takeda Katsuyori married Toyoma Fujin, the adopted daughter of Oda Nobunaga. She died while giving birth to their son Nobukatsu in 1567. Katsuyori later married Hojo Masako, daughter of Hojo Ujimasa. She bore a son and two daughters. In 1582, at the age of 19, she killed herself (jigai), along with her husband. Their daughters married and had families. Their son, Takeda Katsuchika, lived to the age of 103.