
Tokugawa Retainer and Daimyo
石川数正
As a senior retainer of Tokugawa Ieyasu, he served as the leading figure of western Mikawa and was at the center of Ieyasu's domain administration and control of the retainer band. From after Matsudaira Nobuyasu's suicide in Tenshō 7 until his defection in Tenshō 13, he served as castellan of Okazaki Castle. During this period he is said to have been involved in adjusting relations between Ieyasu and Hideyoshi, though details remain unconfirmed. In Tenshō 13 (November 1585), opposing Ieyasu's policy of refusing to submit to Hideyoshi, he defected taking his wife and children along with hostages from the Shinano Ogasawara family. In 1590 Hideyoshi appointed him lord of Matsumoto Castle, and he undertook castle construction together with Yasunaga. However, sources differ on his death year, with some giving 1592 and others 1593.
Sources 国立公文書館『石川数正の出奔』、松本城管理事務所『松本城の歴史』
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1579
Ishikawa Kazumasa Appointed Deputy of Okazaki Castle
Principal partyAfter Nobukatsu's suicide, Ishikawa Kazumasa became deputy of Okazaki Castle as one of Tokugawa's senior retainers. He served in this position from 1579 until his defection in November 1585.
1585
11/13
Ishikawa Kazumasa Defects to Hideyoshi
Okazaki castellan who left the Tokugawa for HideyoshiIshikawa Kazumasa, a senior retainer of Tokugawa and former deputy of Okazaki Castle, defected to Hideyoshi's side, taking his wife, children, and a hostage from the Shinano Ogasawara family. The defection of this senior retainer, well-versed in Tokugawa military organization, proved a serious setback; it is said that Tokugawa subsequently reformed his military system. The reasons for his defection remain uncertain.
1590
Ishikawa Kazumasa Enters Matsumoto
Principal partyIn connection with Toyotomi Hideyoshi's settlement of Kantō and Ōu, Ishikawa Kazumasa entered Matsumoto and undertook renovation of the castle fortifications and development of the castle town. There are theories that his domain was valued at either 80,000 or 100,000 koku.
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