A revolution took place in the centuries from the time of the Kamakura shogunate, which existed with the Tenno's court, to the Tokugawa, when the bushi became the unchallenged rulers in what historian Edwin O. Reischauer called a "centralized feudal" form of government. Instrumental in the rise of the new bakufu was Tokugawa Ieyasu, the main beneficiary of the achievements of Oda Nobunaga and Toyotomi Hideyoshi. Already powerful, Ieyasu profited by his transfer to the rich Kantō area. He maintained two million koku of land, a new headquarters at Edo, a strategically situated castle town (the future Tokyo), and also had an additional two million koku of land and thirty-eight vassals under his control. After Hideyoshi's death, Ieyasu moved quickly to seize control from the Toyotomi family.…