The War of 1812 was fought by the United States and its allies against the United Kingdom and its allies in North America. It began when the United States declared war on Britain 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 the United States Congress on 17 February 1815.
Anglo-American tensions stemmed from long-standing differences over territorial expansion in North America and British support for Tecumseh's confederacy, which resisted U.S. colonial settlement in the Old Northwest. In 1807, these tensions escalated after the Royal Navy began enforcing tighter restrictions on American trade with France and impressed sailors who were originally British subjects, even those who had acquired American citizenship. Opinion in the U.S. was split on how to respond, and although majorities in both the House and Senate voted for war in June 1812, they were divided along strict party lines, with the Democratic-Republican Party in favour and the Federalist Party against. 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.