Battle of Okehazama
During the Muromachi period, the Imagawa clan ruled Suruga Province from their base at Sunpu (modern-day Shizuoka City). It is not certain exactly when a castle was built on this site. After Imagawa Yoshimoto was defeated at the Battle of Okehazama in 1560, Suruga Province passed to the Takeda clan, and then to Tokugawa Ieyasu, who had spent his youth in Sunpu as Yoshimoto's hostage.