This period is often known as the "Era of Good Feelings." The United States concluded the War of 1812 with the Treaty of Ghent in 1815, an event that itself excited considerable nationalism. The Federalists' opposition to the war discredited their party to the point that there was essentially one party (the Democratic-Republicans) in power. James Monroe was president during this period, having been elected in 1816. The period saw an expansion in manufacturing in the northeast, fueled by being cut off from Great Britain during the war as well as protective tariffs afterwards. The period also saw territorial expansion, with the admission of Missouri sparking a sectionalist debate that led to the Missouri Compromise, a measure that many hoped (though just as many probably doubted) would deal with the issue of the expansion of slavery. The period also saw a severe economic downturn with the Panic of 1819. On the foreign policy front, the United States acquired Florida from Spain, and staked a claim to the Oregon Territory. Perhaps the most well-known aspect of American foreign policy during this period was the Monroe Doctrine, which warned European nations not to attempt to establish colonies in the Western Hemisphere.