There is much debate as to who won and lost the War of 1812. While most believe that
the British won and the United States lost the war, there is even debate among those who answered this question. Below are the full arguments on both sides.
The British won due to the fact that they completed their objectives; defend Canada by killing the Americans who tried to invade.
American Deaths:11,300 killed, wounded or missing in action.
British Deaths: 8,600 killed, wounded or missing in action.
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I would also like to add that Britain won the last battle between the two countries - "Battle of Fort Bowyer" and that during the time of this war Britain was also involved in the napoleon war. The Americans having failed all their objectives, forfeited and wanted to sign a peace treaty.
Additional answer: I'd like to add to his slightly. I am in Canada, where most Canadians claim to have won the war due to the American failure to capture Canada. I, however, look at it from this point of view: The British were forced to give up all the land gains they'd made during the war (true, the Americans also had to give back land, but it was not nearly as large an area). As well, the Americans were granted fishing rights in the St Lawrence river, which had previously been solely British. But lost the right to place warships in the great lakes. I believe it was strategically an British victory, as they successfully achieved their sole purpose.
Another Answer: The Americans had their fighting rights in the Maritimes and Great lakes taken away shortly after the war, and not returned until the 1850's. Also, most of the US war aims were never achieved. The returning of territory to the US does not mean that strategically the US won, if that were the case, then the British/Canadians won the war while the US won the peace treaty. Although the US had numerical superiority during the war, the British had more experienced commanders and soldiers for the most part in the early part of the war and by the time the American troops could fight the British on even terms, the British had sent thousands of additional battle trained troops from Europe in 1814. Overall it may be a stalemate militarily, but strategically and politically, if that was true, then the Korean Wars and the Vietnam War, up until the Americans left were also draws.
The Americas didn't win. The objective was to first take Upper Canada which they couldn't do. As I read the stats The Canadians/British controlled more lakes and rivers and killed more Americans. Plus America retreated back to America burning some villages on their way out. That's not winning, that's being a poor loser. No matter which way one looks at it the Americas objective was plain and simple to take over Canada and they retreated. strategically stand point they took more weapons when more British troops arrived they never returned. It's A Canadian win because this is not the first time America had tried to invade Canada and it was also not the first time America had failed.