castle of Shingen's, Ishikura Castle. Both forces met each other in the Battle of Tonegawa, but eventually disengaged after a well-fought fight. Suruga campaign The death of Takeda Yoshinobu is believed to have much to do with the change in Shingen's policy towards the Imagawa clan. After Imagawa Yoshimoto's death in a Battle of Okehazama against Oda Nobunaga in 1560, Shingen made an alliance with the Oda and Tokugawa clan, and started to plan an invasion of Suruga Province, a territory now controlled by Yoshimoto's son, Ujizane. Yoshinobu, however, had strongly opposed such a plan because his wife was the daughter of Yoshimoto. By 1567, nonetheless, after Shingen had successfully kept the forces led by Uesugi Kenshin out of the northern boundaries of Shinano Province, taken over a strategically important castle in western Kōzuke, and suppressed internal objection to his plans to take advantage of the weakened Imagawa clan, he was ready to carry out his planned Suruga invasion. Shingen and Tokugawa Ieyasu "came to terms" and occupied the "former Imagawa territory." They both fought against Yoshimoto's heir, Imagawa Ujizane. During this time Shingen also ordered the damming project of the Fuji River, which was one of the major domestic activities of the time. Conflict with Hojo In 1568, as a response to Hōjō clan intervention in his invasion of Suruga Province, Shingen broke the alliance with the Hōjō, and came into Musashi Province from his home province of Kai, attacking Takiyama Castle. He then moved against the Hojo by attacking Hachigata Castle, then engaged in the Siege of Odawara (1569). He burned Odawara Castle, then successfully withdrew after Hōjō Ujiteru and Hōjō Ujikuni failed to stop him in the Battle of Mimasetoge. After defeating the intervention forces commanded by Hōjō Ujimasa of Sagami Province, Shingen finally secured the Suruga Province, formerly base of the prestigious Imagawa clan, as a Takeda asset in 1569. At this point, Shingen now had Kai Province, Shinano Province, the western part of Kōzuke Province, Musashi Province and Suruga Province. Conflict with Oda–Tokugawa alliance By the time Takeda Shingen was 49 years old, he was the only daimyō with the necessary power and tactical skill to stop Oda Nobunaga's rush to rule Japan. In 1572, upon securing Takeda control over Suruga, northern Shinano, and western Kōzuke, Shingen took Iwamura Castle, which caused the Takeda–Oda relationship to decline. Shingen engaged Tokugawa Ieyasu's forces in 1572 and