Tokugawa Ieyasu, who took power after he defeated Ishida Mitsunari at the Battle of Sekigahara (1600), sent his ninth son, Yoshinao, to Kiyosu Castle to quell the remnant enemy forces and to keep an eye on the western warlords. Yoshinao reinforced the castle, but when he later learned that the area was prone to water hazard, he decided in 1610 to build a new castle, in an area called Nagono. He appointed Kato Kiyomasa to head the project with more than 20 daimyos under him. The city of Nagono began to bustle with carpenters and other craftsmen. The samurais and merchants also left the castle town of Kiyosu to join Yoshinao at his new castle. Even the shrines and temples relocated. This is the famous incident of the "Moving of Kiyosu Castle." The new castle town was renamed Nagoya. It was properly sectored and soon became out of the three leading cities of the Tokugawa family. Especially during the time of Tokugawa Muneharu, the seventh warlord of the Owari clan, the town developed remarkably. Under his lenient policy, dramas, noh plays, flower arrangement, and the tea ceremony cultures flourished. Its foundations as a commercial city were nurtured around this time making Nagoya one of the big trade centers after Yedo, Kyoto, and Osaka.
