On October 17, 1856 Hotta formed and headed an "ad hoc" committee of officials with special knowledge of foreign affairs. In November 1856, he charged the members to come up with recommendations about the terms for opening Japanese ports. The results of their deliberations would become the basis for negotiations which ultimately resulted in the Treaty of Amity and Commerce of 1858 (also known as the Harris Treaty), which open up six ports to American trade, and established extraterritoriality. Based on his knowledge of the events of the Arrow War, Hotta believed that a violent response the United States would arise if the demands of American consul Townsend Harris were refused. However, it was necessary to convince the Emperor Kōmei to accept the treaty. Traveling to Kyoto, Hotta found the Emperor securely in the midst of the "jōi" faction within the Imperial Court, who favored expelling the foreigners from Japan, by force if necessary, and was forced to return to Edo empty-handed. On top of this, "shōgun" Tokugawa Iesada was very ill and factional strife erupted within the Shogunal court over who would be his successor. With these issues still largely unresolved, Hotta was replaced by Ii Naosuke on June 21, 1858, who was given the title of "tairō".