The child shogun died in 1716 and the Tokugawa main line ended, so a branch lord whose three elder brothers had died took the title

Tokugawa Ieyasu founded three branch houses for his 9th, 10th and 11th sons, at Owari, Kii and Mito. They ranked above all other lords and carried the Tokugawa name. Tokugawa Ietsugu, son of the 6th shogun, was born in 1709 and inherited the shogunate at four by Japanese count. The government was run by his chamberlain and the scholar Arai Hakuseki. He died in 1716, a child. The main line of the shogunate ended with him. Tokugawa Yoshimune was the fourth son of the lord of Kii. He had become lord of Kii in 1705 when his elder brothers died one after another. When Ietsugu fell gravely ill in the 4th month of 1716, Yoshimune was made his guardian, and on Ietsugu's death the senior councillors chose him as 8th shogun. He removed Ietsugu's advisers and ruled for 30 years. To make sure the shogunate would not run out of heirs again, he set up two new houses for his own sons, Tayasu and Hitotsubashi; his son added Shimizu. Each held 100,000 koku and could supply a shogun. The 11th shogun, Ienari, came from Hitotsubashi. The 15th and last, Yoshinobu, was born in the Mito house and adopted into Hitotsubashi. He gave up power in 1867.