Drawing on his Confucian beliefs, Nariaki believed that Japan needed a revival of morality in order to combat weakness. He feared that the country may be plunged into chaos if famine or Western imperialism threatened the nation. In response, he called for the shogunate to rebuild the military and economy of Japan (leading to "Fukoku kyōhei") and for the shōgun to provide guidance. The policies of the shogunate, however, continued to provide a barrier to reform in the domains. A few years later in 1836, a nationwide famine occurred, and uprisings spread across Japan as Nariaki had predicted. In 1840, the Opium War began between China and Britain, and Nariaki's predictions about Western interference also appeared to be a legitimate concern. After the events of the 1830s, the shogunate agreed with Nariaki's calls for reform. Despite this agreement, however, the shogunate forced Nariaki into early retirement. This action angered Nariaki's supporters in Mito as well as other "daimyōs" who agreed with Nariaki's beliefs. Later, "Rōjū" Abe Masahiro brought Nariaki out of retirement to be an adviser on foreign policy because he respected Nariaki's experience and views. Additionally, Nariaki's warnings about Western involvement in Japanese affairs also led Abe to conclude that Nariaki was knowledgeable about the issue. Throughout the 1840s, the Western nations applied increasing pressure on Japan to open its market to Western goods. Western pressure on Japan culminated in 1853, with the arrival of Commodore Matthew Perry and the Black Ships, which presented a significant challenge to Japanese isolationism. Perry demanded the opening of Japanese ports for trade with the United States. Abe sought a consensus from the "daimyōs" on how to solve the Western problem. The "daimyōs" failed to reach a consensus on either fighting the United States or agreeing to trade, so Abe had no other option but to agree to the United States' demands in the Convention of Kanagawa. The inability of the shogunate to defend Japan from the West immediately undermined the people's confidence in the bakufu. Consequently, Abe resigned after the event, and Hotta Masayoshi replaced him. In 1858, Hotta met with Emperor Kōmei and submitted the Harris Treaty, which allowed for Westerners to trade in Japan and granted them extraterritoriality.