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.
Latin America–United States relations
Texas, which had been settled by colonies of Americans, fought a successful war for independence from Mexico in 1836. Mexico refused to recognize the independence and warned that annexation to the United States meant war. Annexation came in 1845 and the Mexican–American War began in 1846. The American military was easily triumphant. The result was the Mexican Cession of Santa Fe de Nuevo México and Alta California. About 60,000 Mexicans remained in the territories and became US citizens. France took advantage of the American Civil War (1861–65), using its army to take over Mexico. Due to defeats in Europe, France pulled out troops, leaving the Imperialists and Maximilian I of Mexico to face defeat from the Benito Juarez-led Republicans (backed by the US).