Oda Nobunaga was the son of a minor daimyo who greatly expanded his father's holdings, becoming master of three provinces near present day Nagoya.
The emperor secretly appealed to him for help with the politically powerful monasteries and daimyo, and Nobunaga, acting in the emperor's name, became dictator of central Japan. Though he restored the ousted shogun since his ancestry made him ineligible for that title, the real power was his and, aided by his general Toyotomi Hideyoshi and his ally Tokugawa Ieyasu, he unified all Japan except the extreme north and west.

He broke the temporal power of the great Buddhist sects by destroying their armies and was one of the first Japanese generals to supply his footsoldiers with muskets. The early Jesuits in Japan gained Nobunaga's respect and, thereby, his permission to preach. Under his rule, free trade was encouraged and an era of castle building began. He was murdered by one of his discontented generals before the unification of all Japan, a task that was completed by Hideyoshi and Ieyasu.