The Japanese warrior commander Toyotomi Hideyoshi (1536-1598) completed the military unification of the country in the late 16th century and undertook two invasions of Korea in the 1590s.

The period of the late 15th century and the first half of the 16th is known in Japanese history as the age of provincial wars. During this time neither the ancient imperial court nor the shogunate (military government) of the Ashikaga family, both of which were located in Kyoto in the central provinces of the island of Honshu, exercised any significant control over the country, and fighting among warrior bands raged everywhere. Gradually, however, a group of daimyos (barons) began to impose their rule over extensive territorial domains, and by the mid-16th century much of the land was in their hands. From about the 1550s the greatest of these daimyos, having organized powerful armies composed of infantry as well...