Although often treated as a minor footnote to the bloody European war between France and Britain, the War of 1812 was crucial for the United States. First, it effectively destroyed the Indians' ability to resist American expansion east of the Mississippi River. General Andrew Jackson crushed the Creek Indians at the Battle of Horseshoe Bend in Alabama, while General William Henry Harrison defeated Indians in the Old Northwest at the Battle of the Thames. Abandoned by their British allies, the Indians reluctantly ceded most of their lands north of the Ohio River and in southern and western Alabama to the U.S. government.
Second, the war allowed the United States to rewrite its boundaries with Spain and solidify control over the lower Mississippi River and the Gulf of Mexico. Although the United States did not defeat the British Empire, it had fought the world's strongest power to a draw. Spain recognized the significance of this fact, and in 1819 Spanish leaders abandoned Florida and agreed to an American boundary running clear to the Pacific Ocean.
Third, the Federalist Party never recovered from its opposition to the war. Many Federalists believed that the War of 1812 was fought to help Napoleon in his struggle against Britain, and they opposed the war by refusing to pay taxes, boycotting war loans, and refusing to furnish troops. In December 1814, delegates from New England gathered in Hartford, Connecticut, where they recommended a series of constitutional amendments to restrict the power of Congress to wage war, regulate commerce, and admit new states. The delegates also supported a one-term president (in order to break the grip of Virginians on the presidency) and abolition of the Three-fifths clause in the Constitution (which increased the political clout of the South), and talked of seceding if they did not get their way.
The proposals of the Hartford Convention became public knowledge at the same time as the terms of the Treaty of Ghent and the American victory in the Battle of New Orleans. Euphoria over the war's end led many people to brand the Federalists as traitors. The party never recovered from this stigma and disappeared from national politics.