Shogun was the ultimate rank one could achieve in Japan. The Shogun was the Supreme Military Dictator. Only one Daimyo (feudal lord) at a time could obtain the title. And only the His Imperial Highness, the reigning Emperor, the Divine Son of Heaven, who lived in seclusion with the Imperial Families at Kyoto, could grant the title. With the appointment of Shogun went absolute power: the Emperor's seal and mandate. The Shogun ruled in the Emperor's name. All power was derived from the Emperor because he was directly descended from the gods. Therefore any daimyo who opposed the Shogun were automatically in rebellion against the throne, and at once outcast and all his lands forfeit. The reigning Emperor was worshipped as a divinity because he was descended in an unbroken line from the Sun Goddess, Amaterasu Omikami, one of the children of the gods Izanagi and Izanami, who had formed the islands of Japan from the firmament. By divine right the ruling Emperor owned all the land and was obeyed without question. But in practice, for more than six centuries real power had rested behind the throne.
A Shogunate was the government, office, or rule of a Shogun. There was three shogunates in Japanese history.
1) Kamakura Shogunate (1192–1333)
2) Ashikaga Shogunate (1336–1573)
3) Tokugawa Shogunate (1603–1868)