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.
Republic of Yucatán
In 1810, the priest Miguel Hidalgo y Costilla issued the "Grito de Dolores" (in effect a call for independence) in Dolores near Guanajuato. An army of insurgents began an eleven-year war of independence that culminated in a Mexican victory over the viceroy's armies. In 1821 the Mexicans offered the crown of the new Mexican Empire to Ferdinand VII or to a member of the Spanish royal family that he would designate. After the refusal of the Spanish monarchy to recognize the independence of Mexico, the "" (Army of the Three Guarantees), led by Agustín de Iturbide and Vicente Guerrero, cut all political and economic dependence on Spain. The Plan of Iguala established Roman Catholicism as Mexico's religion and equality for all social and ethnic groups in the new empire. These goals were summarized as "Religion, Independence and Unity" ("Religión, Independencia y Unión").