Spanish attempts to reconquer Mexico
Mexican independence was officially achieved on September 27, 1821, under the Treaty of Córdoba. Spain did not recognize the treaties, arguing that the viceroy Juan O'Donojú had no authority to recognize the independence of any overseas province. This situation was dangerous to the newly acquired independent status of the nation, which had not yet been recognized by any of the European powers that could support it, and the threat of Spanish reconquest was a constant worry to the leaders of the nascent regime. On May 13, 1822 decrees were issued by the government to imprison anyone who conspired against Mexico's independence.
Japan–Mexico relations
In 1874 (fifty-three years after Mexico declared independence from Spain in 1821), a Mexican scientific delegation headed by Francisco Díaz Covarrubias arrived in Japan to witness the transit of the planet Venus through a solar disc. Although the scientific delegation did not have much success, this mission did allow for formal diplomatic relations to begin between the two nations. In 1888 Foreign Ministers Matías Romero and Munemitsu Mutsu signed a Treaty of Amity, Commerce, and Navigation; which was to be Japan's first "equal" treaty with a foreign nation and thus formally established diplomatic relations between the two nations.