From Wikipedia

The War of 1812

Between the United States of America and the British Empire (particularly Great Britain and British North America), was fought from 1812 to 1815.

There were several immediate stated causes for the U.S. declaration of war: first, a series of trade restrictions introduced by Britain to impede American trade with France, a country with which Britain was at war (the U.S. contested these restrictions as illegal under international law); second, the impressment (forced recruitment) of U.S. citizens into the Royal Navy; third, the British military support for American Indians who were offering armed resistance to the expansion of the American frontier to the Northwest. An unstated but powerful motivation for the Americans was the need to uphold national honor in the face of what they considered to be British insults (such as the Chesapeake affair).

American expansion into the Northwest (Ohio, Indiana, Michigan, Illinois and Wisconsin) was impeded by Indian raids. Some historians maintain that Americans wanted to seize parts of Canada, while others argue this was merely a tactic designed to obtain a bargaining chip. Some members of the British Parliament at the time and dissident American politicians such as John Randolph of Roanoke also claimed that land hunger rather than maritime disputes was the main motivation for the American declaration. Although the British made some concessions before the war on neutral trade, they saw themselves as having the right to reclaim their deserting sailors, and also as the protectors of the native Amerindians from encroaching settlers. The British also had the long-standing goal of creating a large "neutral" Indian state that would cover much of Ohio, Indiana and Michigan. They made the demand as late as 1814 at the peace conference, but lost battles that would have validated their claims.

The war was fought in four theatres: on the oceans, where the warships and privateers of both sides preyed on each other's merchant shipping; along the Atlantic coast of the U.S., which was blockaded with increasing severity by the British, who also mounted large-scale raids in the later stages of the war; on the long frontier, running along the Great Lakes and Saint Lawrence River, which separated the U.S. from Upper and Lower Canada (Ontario and Quebec); and finally along the coast of the Gulf of Mexico, where U.S. General Andrew Jackson defeated the Creek Indians at the Battle of Horseshoe Bend (1814) and a major British regular army at the Battle of New Orleans (early 1815).