The U.S. Launches One Big Invasion of Canada in 1812

The problem is that with the Napoleonic Wars winding down, the United Kingdom could send thousands of Napoleonic Wars veterans to the American front, even with a much more competent military leadership the United States will still suffer and might still loses. 

In 1812 Britain is still heavily preoccupied with the French threat so massive amounts of support of Canada is difficult. However how does the US get the military and organisational skill immediately at the start of the war that to a degree they obtained later? It takes a while for most pece-time armies to really get compenent at warfare and clear out the dead-wood of ideas, bad officers, etc.

Also there are serious logistical problems with American forces reaching the Canadian heartland at this point. You would still have to fight through Indian territory in a lot of places, especially if as OTL New England is hostile to the war. Then you have to conquer the Canadians themselves who, whether Anglos or French largely identify themselves as NOT Americans.

Its possibly that most of the settled population areas of Canada could be overrun but, presuming Napoleon still falls as OTL you have earned the emnity of the world's leading industrial, economic and naval power with access to vast funds and powerful allies and almost certainly still some useful bases. Hence you have to hold down Canada and face off whatever retaliation Britain seeks which would mean a prolonged period of high military spending and disruption of much economic activity, which is unlikely to be popular for long.

It might be the case that Britain after Napoleon's defeat is eager enough to have peace to accepted the annexation of much of Canada but after what it will see as a stab in the back its not something to be relied upon. OTL Britain was willing to agree a return to the status quo anti but that was with Canada cleared of American forces and it actually gave up some US territories it held. TTL Britain is likely to be a lot angier and there will be the danger of a massive loss of face it if just accepts the American conquests so I strongly suspect it would mean war until at least some of Canada, and probably most/all are liberated.

Quebec might become a independent pro-United States country, that would be something the French will like i guess.

The event of a US victory is likely to have consequences in Europe. If the UK sends more troops and diverts more money to the N-American theatre, Napoléon could benefit from this. For example, if Wellington and half his army are rerouted to Canada, Spain is not lost for the French (Salamanca is july 22 1812 and Vitoria June 21, 1813). With a victory over the Spanish and remaining British, Napoléon can divert more troops from the Peninsule and strengthen his Central European armies.

Agreed, Napoléon was not in a position of power in 1815. Nonetheless, without Waterloo, maybe he could manage a transfer of power to his son. The young Napoléon II was, after all, Franz's grandson.

Napoléon himself would go west to the US and finally win against Wellington in an epic Second Battle of the Plains of Abraham ! Sadly, that list bit is unrealistic.

Despite the adverse British propaganda, Napoléon's image was not so dark in 1815, especially in a country at war with the UK. Anyways, I was just referring to an epic rematch of both Waterloo and the Plains of Abraham, french defeats that even non-imperialists Frenchmen cannot help to regret. I am not a fan of Napoléon's politics and I found many of his policies ultimately downgrading France's assets.

My idea is that, with a military stalemate in Europe, the Napoléon II solution is a compromise. Napoléon goes down quietly, Talleyrand takes the rein (his ultimate goal all along was a liberal regime, be it a constitutional monarchy or an Empire of the French), the Bourbons are compensated in Italy, and Austria takes the lead. Of course, the British, once they have deal with the US, will try to undermine the Austrian supremacy by rallying up the Prussians and the Russians.

That's the all point, isn't it ? If Napoléon beats the British-Prussians in 1815 (the only turning point of this timeline), could he beat the Austrians and the Russians in successive battles or at least held them at bay, long enough for the British to seek a compromise ?