The prelude to this would be the Louisiana Purchase of 1803, when Napoleonic France sold Louisiana to the U.S. for $15 million. Napoleon needed the money to finance his campaigns in Europe, while the U.S. sought to claim the vast "Indian" territory in the Mississippi Valley that remained sparsely settled, even after the territory was nominally ceded to Spain at the end of the Seven Years War and the British conquest of Quebec. The Spanish were absentee landlords and never really developed or enforced this claim outside of New Orleans, when the French briefly reacquired it.

But, while American settlers had expanded west of the Appalachians after the War of Independence, they were technically encroaching on land (roughly, the Ohio Valley region) that the British had granted to the indigenous peoples at the end of the Seven Years War. The U.S. soon found itself in conflict with the natives already living on the frontier, with both sides raiding and razing settlements and committing atrocities in the lead up to the War of 1812.

The British traded with the natives openly and still held forts in the area, leading US legislators in the frontier to object to what they saw/believed was British collusion or complicity in assisting native resistance to American westward expansion. The British colony of Upper Canada (Ontario), created in 1791, was also directly en route and American statesmen began to agitate for an eventual invasion of Canada -- either as a bargaining chip in negotiations with Britain, or an opportunity to expel British authority entirely from North America and deny the natives their only remaining (and powerful) European ally.

The British Navy required 140,000 sailors to keep their ships afloat during the wars with France and often found itself short of hands, due to losses from battle, illness or desertion. They impressed into service American sailors (up to 15,000), who were technically neutral in the war against France -- but had traded freely with the French, in defiance of the British blockade of French ports. This, combined with the issue of neutrality rights were the main grievances listed in the U.S. declaration of war against Britain in June 1812.

While the capture or conquest of Canada was certainly an objective in U.S. war aims, Britain's aims in North America were limited by their burdensome commitments in fighting Napoleon in Europe. Theirs was a war of defence: to hang onto their Canadian possessions. British regulars in Canada were professional, with many -- enlisted and officers -- having previous experience serving in Europe or across the Empire. But with limited resources and manpower, they had to rely on both native alliances and the local militia (of questionable skills and reliability) to bolster their ranks.

America had every intention of exploiting Britain's vulnerable situation in Canada, but underestimated the resolve of the defenders and the local colonists -- and overestimated the U.S. ability to pursue a clear strategy and wage war effectively in 1812. When hostilities began, most of its officer corps were aged veterans of the Revolution, leading largely part-time state militias of varied ability and commitment. Reforms were under way, but would take time to materialize. In 1814, they could field a regular army that could match British veterans, but by then, events in Europe would soon overtake them.

The war's eventual end was arguably "settled" not in Upper Canada, Washington or New Orleans, but in the aftermath of the 1813 Battle of Leipzig. Napoleon was resoundingly defeated, his dream of French hegemony in Europe shattered. Austria, Prussia, Russia and Britain invaded France itself in 1814. Napoleon abdicated, ending a quarter century of constant warfare.

This meant Britain no longer needed a vast pool of sailors to man its enormous navy, making the naval impressment problem a non-issue. British resources could now be brought to bear on America. The British fleet blockaded American ports with relative impunity (despite some ship-to-ship losses), captured Maine and strangled U.S. trade in the Atlantic. British veterans from European campaigns burned down Washington DC.

By the time peace negotiations began at Ghent, Britain was weary of war and the U.S. government was practically broke. Both sides were ready to make peace, quickly. America won at New Orleans, but the treaty had already been signed. Britain successfully defended Canada, but reneged on pledges to the natives to safeguard a native homeland, thus opening up the west to future settlement.

Historians largely agree that the war was a draw. They also agree that the indigenous peoples lost the most.