The War of 1812 was the conflict between the United States of America and its native friends against the U.K. and its supporters in British North America, with minimal involvement by Spain in Florida. It started when the United States declared war on 18 June 1812, and although settlement conditions were established in the Treaty of Ghent in December 1814, it did not formally cease until approved by Congress on 17 February 1815.

Tensions arose from lengthy disagreements about North American territorial expansion and British assistance for Native American nations hostile to US colonial establishment in the Northwest Territory. In 1807, the Royal Navy began imposing stronger limitations on U.S. trade with France, which was aggravated by the conscription of people claiming to be British nationals, including some with American citizen documents. Although votes in both the House and Senate voted in favor of the war, they did so along tight electoral politics, with the Democratic-Republican Party in favor and the Federalist Party opposed. The US did not learn of the British deals made in a bid to prevent war until late July, by which point the combat had already begun.

At sea, the vastly bigger Royal Navy effectively blocked US sea routes, while British locals and provincial troops fought a succession of American raids on Upper Canada from 1812 to 1814. This was offset by the US gaining possession of the Northwest Territory in 1813, thanks to successes at Lake Erie and the Thames. With Napoleon's surrender in early 1814, the British were able to send more soldiers to North America as well as the Royal Navy to strengthen their blockade, devastating the American commerce. Both parties wanted peace when discussions began in Ghent in August 1814; the British industry had been seriously harmed by the trade blockade, and in December Federalists held the Hartford Convention to codify their resistance to the conflict.