What was the Monroe Doctrine?

The Monroe Doctrine was the young United State's response to the turmoil caused by the Napoleonic Wars. After Napoleon conquered Spain in 1808, the Latin American countries under Spanish rule revolted, and by 1822 all of South America (except Guiana) was freed from foreign rule, as were most of the islands in the Caribbean. In North America, only Canada and Alaska were under foreign control. Great Britain supported the revolutions as they opened trade with the Americas. The Quadruple Alliance, consisting of Russia, Prussia, Austria, and Great Britain, attempted to keep order in Europe after Napoleon; when it began attempts at restoring Spanish colonies in the New World, Great Britain withdrew. In 1821, The Czar of Russia, having established trading posts in Northern California, forbid vessels to sail to the Oregon Coast. Secretary of State John Quincy Adams bluntly asserted American rights to sail in the Pacific, Congress recognized the independence of all the revolutionary governments in Latin America, and President Monroe announced the foreign policy that bears his name, which declared that the Western Hemisphere was no longer open to European colonization, that any attempt to establish colonies would be considered an unfriendly act towards the US, and that the US would not interfere with Latin American governments or European affairs. This Doctrine became a cornerstone of US foreign policy, and was expanded under President Theodore Roosevelt.