If the British win the Napoleonic War then any US victory is going to be in the short term only. Once Europe is at peace the British inevitably arrive in sufficient force to break the US.
Against a truly vengeful UK the US could well lose Montana, North Dakota, Wisconsin, Minnesota, Oregon, Idaho, Washington State, and Michigan while New England probably secedes with or without New York. Later the UK props up Mexico against the US and the Mexican Northwest never changes hands...
Once again, if the US doubles or triples the standing army and navy there WILL be a British response and the British can far more easily divert existing forces to Canada than the US can invent forces from scratch.
Against a truly vengeful UK the US could well lose Montana, North Dakota, Wisconsin, Minnesota, Oregon, Idaho, Washington State, and Michigan while New England probably secedes with or without New York. Later the UK props up Mexico against the US and the Mexican Northwest never changes hands...
Once again, if the US doubles or triples the standing army and navy there WILL be a British response and the British can far more easily divert existing forces to Canada than the US can invent forces from scratch.