During the opening decades of the 19th century, Central and South America turned to revolution. The idea of liberty had stirred the people of Latin America from the time the English colonies gained their freedom. Napoleon's conquest of Spain in 1808 provided the signal for Latin Americans to rise in revolt. By 1822, ably led by Simon Bolivar, Francisco Miranda, Jose de San Martin and Miguel Hidalgo, all of Hispanic America -- from Argentina and Chile in the south to Mexico and California in the north -- had won independence from the mother country.
The people of the United States took a deep interest in what seemed a repetition of their own experience in breaking away from European rule. The Latin American independence movements confirmed their own belief in self-government. In 1822 President James Monroe, under powerful public pressure, received authority to recognize the new countries of Latin America -- including the former Portuguese colony of Brazil -- and soon exchanged ministers with them. This recognition confirmed their status as genuinely independent countries, entirely separated from their former European connections.
At just this point, Russia, Prussia and Austria formed an association called the Holy Alliance to protect themselves against revolution. By intervening in countries where popular movements threatened monarchies, the Alliance -- joined at times by France -- hoped to prevent the spread of revolution into its dominions. This policy was the antithesis of the American principle of self-determination.
As long as the Holy Alliance confined its activities to the Old World, it aroused no anxiety in the United States. But when the Alliance announced its intention of restoring its former colonies to Spain, Americans became very concerned. For its part, Britain resolved to prevent Spain from restoring its empire because trade with Latin America was too important to British commercial interests. London urged the extension of Anglo-American guarantees to Latin America, but Secretary of State John Quincy Adams convinced Monroe to act unilaterally: "It would be more candid, as well as more dignified, to avow our principles explicitly to Russia and France, than to come in as a cock-boat in the wake of the British man-of-war." In December 1823, with the knowledge that the British navy would defend Latin America from the Holy Alliance and France, President Monroe took the occasion of his annual message to Congress to pronounce what would become known as the Monroe Doctrine -- the refusal to tolerate any further extension of European domination in the Americas:
The American continents...are henceforth not to be considered as subjects for future colonization by any European powers.
The Monroe Doctrine expressed a spirit of solidarity with the newly independent republics of Latin America. These nations in turn recognized their political affinity with the United States by basing their new constitutions, in many instances, on the North American model.
Source: U.S. Department of State