The War of 1812 (18 June 1812 – 17 February 1815) was fought by the United States of America and its indigenous allies against the United Kingdom and its own indigenous allies in British North America, with limited participation by Spain in Florida. It began when the United States declared war on 18 June 1812. Although peace terms were agreed upon in the December 1814 Treaty of Ghent, the war did not officially end until the peace treaty was ratified by Congress on 17 February 1815.^[27]

Tensions originated in long-standing differences over territorial expansion in North America and British support for Native American tribes who opposed U.S. colonial settlement in the Old Northwest. These escalated in 1807 after the Royal Navy began enforcing tighter restrictions on American trade with France and press-ganged men they claimed as British subjects, even those with American citizenship certificates.^[28] Opinion in the U.S. was split on how to respond, and although majorities in both the House and Senate voted for war, they divided along strict party lines, with the Democratic-Republican Party in favour and the Federalist Party against.^[29] News of British concessions made in an attempt to avoid war did not reach the U.S. until late July, by which time the conflict was already underway.

At sea, the Royal Navy imposed an effective blockade on U.S. maritime trade, while between 1812 and 1814 British regulars and colonial militia defeated a series of American attacks on Upper Canada.^[30] The abdication of Napoleon in early 1814 allowed the British to send additional troops to North America and the Royal Navy to reinforce their blockade, crippling the American economy.^[31] In August 1814, negotiations began in Ghent, with both sides wanting peace; the British economy had been severely impacted by the trade embargo, while the Federalists convened the Hartford Convention in December to formalise their opposition to the war.

In August 1814, British troops captured Washington, before American victories at Baltimore and Plattsburgh in September ended fighting in the north. In the Southeastern United States, American forces and Indian allies defeated an anti-American faction of the Creek. In early 1815, American troops defeated a major British attack on New Orleans.