Since its creation, the United States of America has been in a number of wars. The first of course was the American Revolutionary War or as some call it, The War of Independence that was fought from 1775 to 1783 prior to the USA becoming a nation.
Between the revolutionary war and the American Civil War (1861 - 1865) was the War of 1812,  a little known conflict fought between the United States and the British and its new colony Canada from June 1812 to February 1815.
Historians' debate whether the desire to annex some or all of British North America or Canada as it was to be called, contributed to the American decision to go to war. Though the the War of 1812 lasted for two and a half years, it was actually more of a series of military skirmishes. As a colony of Great Britain, Canada was swept up in the war and was invaded several times by the Americans. The war was fought in Upper Canada, Lower Canada, on the Great Lakes and the Atlantic, and in the United States with each invasion being repelled by the Canada / British forces and their allies.
The immediate cause of the War of 1812 were a series of economic sanctions taken by the British and French against the US as part of the Napoleonic Wars and American outrage at the British practice of impressment, colloquially the kidnapping of men into a military or naval force by compulsion, a not uncommon practice in those days.
Matters came to a head between the USA and Britain after the Chesapeake incident of 1807. The Chesapeake–Leopard affair as it is historically known was a minor naval battle that occurred off the coast of Norfolk, Virginia, on June 22, 1807. The engagement took place between a British warship HMS Leopard and the American frigate USS Chesapeake. The crew of Leopard pursued, attacked, and boarded the American ship looking for deserters from the Royal Navy. Chesapeake was caught unprepared and after a short battle involving broadsides received from Leopard, the commander of Chesapeake surrendered to the British. The Chesapeake had only fired one shot.
The incident created uproar among Americans. There were strident calls for war with Great Britain that President Thomas Jefferson initially attempted to use to diplomatically threaten the British government into settling the matter. The United States Congress backed away from armed conflict when British envoys showed no contrition for the Chesapeake affair, delivering proclamations reaffirming continuing the practice of impressments. Jefferson's political failure to coerce Great Britain led him toward economic warfare known as the Embargo of 1807.
These embargoes hurt the US far more than they did Britain. The anger of American citizens provided support to the War Hawks in Congress. In 1812, with President Madison now in office, Congress declared war against the British. Although the United States was officially at war with Great Britain, more than half of the British forces were made up of Canadian militia. Additionally, many Native Americans/First Nations people fought in the war for reasons of their own. The war ended with the peace treaty of Ghent (1814), which, largely returned the status quo to all parties involved as no land was ceded by either side.
However, in Canada, the war contributed to a growing sense of national identity, including the idea that civilian soldiers were largely responsible for repelling the American invaders. In contrast, the First Nations allies of the British and Canadian cause suffered a great deal because of the war; not only had they lost many warriors they also lost any hope of halting American expansion in the west.
Their contribution to the war efforts was quickly forgotten by their British and Canadian allies after the peace treaty was ratified.
Because the War of 1812 ended in a stalemate, it is only dimly remembered, particularly in the United States.