Seiitaishôgun (征夷大将軍), "Supreme Commander Against the Barbarians", often shortened simply as shôgun (将軍), was originally a temporary Court commission assigned to courtier military commanders in the 8th century frontier campaigns against the Emishi in northern Honshu. It later became a hereditary distinction acknowledging the recipient as the buke no tôryô], "Head of the Warrior Houses", and titular head of the three bakufu warrior governments.
In 1192 Minamoto Yoritomo, as head of the newly established Kamakura Bakufu, was invested with the seiitaishôgun title by the Court, which he returned in 1193. Following his death in 1199 the bakufu had the Court appoint his sons in turn as shôgun, beginning the link of the title with the titular head of the bakufu. After the murder of both Yoritomo's sons, the bakufu brought children of Kyoto courtiers and Emperor's children to serve as shôgun for the remainder of the Kamakura Period, though none held any actual power, instead serving as figureheads of the regime.
Following the destruction of the Kamakura Bakufu, Ashikaga Takauji established his own Muromachi Bakufu, and was awarded the title of shôgun in 1338. The power Takauji wielded as shôgun was comparable to that which Yoritomo held, and was passed down through several generations of Ashikaga shôgun. As unrest grew throughout the nation in the 15th century, the Ashikaga shôgun began to lose their hold over the provinces, with the outbreak of the Onin War and the subsequent civil warring effectively removing them from national influence, useful only as political tools to warlords with their eye on national hegemony. The final Ashikaga shôgun, Ashikaga Yoshiaki, was evicted from Kyoto by Oda Nobunaga in 1573, bringing to an end the line of Ashikaga shôgun.
Following the Battle of Sekigahara and Tokugawa Ieyasu's grasp of the realm, Ieyasu was granted the title of shôgun in 1603 as head of the Tokugawa Bakufu located in Edo, passing the title down to his son Hidetada two years later. The Tokugawa clan continued to reign as shôgun throughout the Edo Period until the Imperial Restoration of 1867.
(See also: Chinjufu shôgun, daishôgun)