In AD 1573 a warlord from central Japan, Oda Nobunaga (1534-82), forced the last shogun, Ashikaga Yoshiaki, out of Kyoto. Nobunaga began his own programme of military domination and unification, only to be defeated by one of his own supporters in 1582, whereupon he took his own life. Another warrior, Toyotomi Hideyoshi (1537-98) then gained the upper hand and began instituting his own administrative changes.

When Hideyoshi died his heir was not yet of age. One of the men enlisted to safeguard the boy’s interests, Tokugawa Ieyasu (1543-1616), managed to defeat his rivals in the great Battle of Sekigahara in 1600. He assumed the title of shogun in 1603, and established the succession by resigning in favour of his son soon after. His ultimate victory, however, did not come until 1615 when he defeated the forces loyal to Hideyoshi’s heir at their stronghold in Osaka.

In a gradual and cumulative process, this succession of ‘three great unifiers’ achieved national unification. Increased control of land and agricultural production by the various daimyo (warlords) who served them also facilitated this. A unified system of taxation provided the financial means to maintain political gains won through battle, and restrictions on status changes brought a necessary social stability.