In feudal Japan, the death of a strong leader usually signaled a new round of fighting among rival samurai clans. Shogun Tokugawa Ieyasu ended that. Appointed shogun in 1603, he established an orderly government with stern measures to curb the power of the daimyo. Several years before his death at the age of seventy-four, Ieyasu resigned as shogun so that his son could assume the position and be firmly in power when Ieyasu died. The plan worked exceedingly well, as members of the Tokugawa lineage ruled for 250 years.

Peace among the daimyo was enforced with an iron hand during the Tokugawa era. The imperial court and Buddhist monasteries were treated with respect, but their activities, too, were closely monitored and controlled. Moreover, Ieyasu started Japan on a strict policy of cultural isolation. Foreigners, including Christian missionaries who had begun making converts, even among the samurai...