Nobunaga was head of the very powerful Oda clan, and launched a war against other "daimyō" to unify Japan in the 1560s. Nobunaga emerged as the most powerful "daimyō", overthrowing the nominally ruling "shōgun" Ashikaga Yoshiaki and dissolving the Ashikaga Shogunate in 1573. He then conquered most of Honshu, and defeated the "Ikkō-ikki" rebels by the 1580s. Nobunaga's rule was noted for innovative military tactics, fostering free trade, reform of Japan's civil government, and encouraging the start of the Momoyama historical art period, but also for the brutal suppression of opponents, eliminating those who refused to cooperate or yield to his demands. Nobunaga was killed in the Honno-ji Incident in 1582 when his retainer Akechi Mitsuhide ambushed him in Kyoto and forced him to commit "seppuku". Nobunaga was succeeded by Toyotomi Hideyoshi who along with Tokugawa Ieyasu completed his war of unification shortly afterwards.