Tokugawa Ieyasu (1542-1616) was the founder and first shogun of the Tokugawa shogunate, or military government, which maintained effective rule over Japan from 1600 until 1867.

The period from 1477 until 1568 was a time of disorder and disunity in Japan. The traditional government of the country, the imperial court at Kyoto, had 1 1/2 centuries earlier delegated ruling authority to the shogunate of the warrior family of Ashikaga, which also had its offices in Kyoto. But, although the Ashikaga shoguns had managed to maintain a loose control over much of the land until about 1477, thereafter their central power virtually disappeared. For the remainder of the 15th century and during the first half of the 16th, warrior families everywhere were constantly at war.

By about the 1550s, however, a group of daimyos (regional barons) had succeeded in establishing stable territorial domains throughout much of the country. In 1568 one of these daimyos, Oda Nobunaga, entered...