Tokugawa Gosanke (three privileged branches of the Tokugawa family) (徳川御三家)
Tokugawa Gosanke, also simply called Gosanke, refers to the following three families of the Tokugawa clan that were second in rank to the Tokugawa Shogunate Family.
Owari-Tokugawa family (the Owari family and the Owari domain) founded by Yoshinao TOKUGAWA, the ninth son of Ieyasu TOKUGAWA
Kishu-Tokugawa family (the Kishu family and the Kishu domain) founded by Yorinobu TOKUGAWA, the tenth son of Ieyasu TOKUGAWA
Mito-Tokugawa family (the Mito family and the Mito domain) founded by Yorifusa TOKUGAWA, the eleventh son of Ieyasu TOKUGAWA
Summary
They were in the highest position among Tokugawa's relatives, and were privileged to refer to themselves as Tokugawa, along with Tokugawa Shogunate Family and Gosankyo (three other privileged branches of the Tokugawa family), and to use the family crest of Mitsuba-aoi (three leaves of hollyhock). However, only the family heads and their heirs were allowed to claim to be Tokugawa. Mitsuba-aoi were slightly different between each family; the hollyhock crest with a front view of three leaves was only used by Seii taishogun (literally, "the great general who subdues the barbarians") while the one with two front-sided and one back-sided leaves was for the Owari family, the one with one front-sided and two back-sided leaves was for the Kishu family, and the one with three back-sided leaves was for the Mito family. While it is said by some that Tokugawa Gosanke assisted the head family or Seii taishogun, this was not officially defined as a system or official post. It is also said that they had originally been intended by Ieyasu for the head family to continue, in preparation for when the family's lineage became extinct. Since the Mito family founded by Yorifusa only received the honor of taking the name of Tokugawa after the Suruga family became extinct in 1636, they were lower in rank and grade than the other two families; however, they reported to the Emperor on the next shogun family, and they worked full time in Edo, so that they came to be called Gosanke when Tsunayoshi became the fifth shogun.
If the shogun family had no inheritors, it was supposed to adopt a son from the Owari or Kishu families; the shoguns from Yoshimune TOKUGAWA, the eighth, through Iemochi TOKUGAWA, the fourteenth, came from the Kishu family. Gosanke, especially the Owari and Kishu families, were competitive against each other over the succession of shogunate, and it is believed that Yoshimune, who was from the Kishu family, and Muneharu TOKUGAWA, who was the head of the Owari family, were at odds, with the Owari family suspected to have poisoned Yoshimune. The fifteenth shogun Yoshinobu TOKUGAWA was of the Mito family, but he became a member of the shogun family after being adopted into the Hitotsubashi-Tokugawa family, one of Gosankyo.
In the early Edo period, the three families, consisting of the Tokugawa head family, along with the Owari-Tokugawa and Kishu-Tokugawa families, were sometimes called Gosanke, and the three dainagon (major counselor) families consisting of the Owari and Kishu families, with the addition of the Suruga-Tokugawa family (Tadanaga TOKUGAWA, the major counselor of Suruga, the third son of Hidetada TOKUGAWA, also called MATSUDAIRA), were also sometimes called Gosanke, although the Mito family was the family of chunagon (middle counselor) and considered lower in family status than the Owari and Kishu families. In addition to the three families noted above and the Suruga family, the branch families of the Tokugawa shogun family included the Kofu-Tokugawa family (Tsunashige TOKUGAWA, Ienobu TOKUGAWA and the Matsudaira family of Sama no kami (Captain of the Left Division of Samaryo)) and the Tatebayashi-Tokugawa family (Tsunayoshi TOKUGAWA and the Matsudaira family of Uma no kami (Captain of the Right Division of Bureau of Horses)), who were equivalent in both crop yield and social standing; however, the Echizen-Matsudaira family, founded by Hideyasu YUKI, who was a son of Ieyasu TOKUGAWA and older brother of Hidetada TOKUGAWA, and the Aizu-Matsudaira family, founded by Masayuki HOSHINA, who was a son of Hidetada and younger brother of Iemitsu TOKUGAWA, were not privileged to claim to be TOKUGAWA. But when Tadanaga SURUGA was dismissed from the position and later killed himself, Tsunayoshi TATEBAYASHI became the fifth shogun, and Tsunatoyo KOFU, who was later renamed to Ienobu, became the sixth shogun and returned to the Tokugawa head family, these Tokugawa families died out and the Owari, Kishu and Mito families came to be commonly called Gosanke.
The Suruga family's official rank was the first appointment Jushiinoge (Junior Fourth Rank, Lower Grade) Saisho no Chujo and kyokkan (the highest rank appointed) Junii rank, Dainagon (chief councillor of state). The ranks of Goryoten (the Kofu and Tatebayashi families) and Gosankyo (the Tayasu, Hitotsubashi and Shimizu families) were the first appointment Jusani (Junior Third Rank) Chujo (Middle Captain) and Kyokkan (the highest rank appointed) Gon Chunagon (Provisional Middle Counselor). Mitsunaga MATSUDAIRA was Jusani Chujo while Tadamasa MATSUDAIRA was Shoshiinoge (Senior Fourth Rank, Lower Grade) Saisho. Therefore, in terms of official ranks, the Owari, Kishu and Suruga families were almost equivalent, as Goryoten, Gosankyo and the Mito families were almost equivalent and lower than Gosanke but higher than the Echizen-Matsudaira clan.
Families and Vassals of Gosanke
Basically, many of the vassals of Gosanke had the hereditary vassals from Mikawa Province as their ancestors just like the shogun family; some vassals of high rank were called 'tsukegaro' (vassals assigned directly by the shogun) who were treated like a great vassal of shogun, held a special position of superintendent officer, and were equivalent to daimyo with tens of thousands of crop yield, while vassals of daimyo were usually called 'baishin' (indirect vassal).
Since Gosanke acted as a backup bloodline for the shogun family, they necessarily had their own branch domains as a reserve system in order for them to retain their family head, so they had branch families called Gorenshi or Renshi (brothers of prestigious noblemen). Takasu, Saijo and Takamatsu Domains were renshi of the Owari, Kishu and Mito families, respectively, and their family names were all Matsudaira; even in Gosanke, only the family heads and their heirs were privileged to use the name of Tokugawa as the names of others were Matsudaira. For instance, Munenao TOKUGAWA of the Iyo-Saijo family became the head of the Kishu family when Yoshimune TOKUGAWA, previously the head of the Kishu family, joined the head family as the eighth shogun. Also, in the end of the Edo period, Yoshikatsu TOKUGAWA, the head of the Owari family, was adopted from the Mino-Takasu family. Legal wives of Gosanke were specifically called gorenju (literally, "behind the screen").
After the eighth shogun Yoshimune, Gosankyo, which was modeled after Gosanke, was established and served to offer heirs to the shogun family along with Gosanke.