Roju shuza (the head of Roju, senior councilors of the Tokugawa shogunate) Tadakuni MIZUNO, who led Tempo Reforms, believed that foreigners might attack Japan in the future, considering the defeat of Qing in the Opium War and the situation in those days in which foreign ships were frequently witnessed in the sea around Japan.
天保の改革を主導した老中首座水野忠邦は、アヘン戦争で清国がイギリスに敗れ、また日本近海にも外国船がしばしば出没する状況にてらし、将来、日本にも外国が攻めてくることもありうるとみていた。