Because the 14th Seiitaishogun Iemochi TOKUGAWA assumed office in 1858 still in his youth, Yoshiyori TAYASU from gosankyo (three privileged branches of the Tokugawa family) was chosen to take this role in August of the same year, in the name of the will of former Shogun Iesada TOKUGAWA and the precedent of Masayuki HOSHINA filling this role for the 4th Shogun Ietsuna TOKUGAWA and Sadanobu MATSUDAIRA for the 11th Shogun Ienari TOKUGAWA (both shogun were assumed office in youth).
安政6年（1858年）、幼少の徳川家茂が14代征夷大将軍に就任したために、同年8月前将軍徳川家定の遺命と、同じく幼少で将軍に付いた4代将軍徳川家綱時の保科正之・11代将軍徳川家斉における松平定信時の先例を名目に御三卿の田安慶頼が任命された。