Canada CAN'T be used as a huge base for a number of reasons. One is that it is sparsely settled and is relatively little developed. There just is not that many people living in Canada. Two is that it is far away, thousands of miles which makes everything EXPENSIVE for the Brits . The US was a highly industrialized country not a technological backwater a century or two behind the times so it was HEAVILY ARMED AND WELL SUPPLIED. Three it has its empire to run and every man sent to North America can't be used to guard an empire that the rest of Europe is eying. To fight the US it needs to send tens of thousands plus many ships to supply them. Four, as I said the US had a larger population the GB did at the time so it can raise a larger army and the few people living in Canada won't help much. A few months of no international trade is NOT that big of a deal for the US, which can feed itself, fuel itself and arm itself entirely. It wouldn't need to import food, fuel or metals. It would take more than a few months for it to bite. The UK has no way of compelling the US to pay for it to go away. Also it is a two way street. GB would be compelled to buy food from somewhere else than the US and at considerably higher prices as it would import from there if it were cheaper. Trade with the US was very profitable to the British Merchant Class which would scream bloody murder at it being cut off. The Brits had large investments in the US which would be seized and sold if it went to war with the US. The London Exchange would instantly crash the moment war broke out for these reasons. For all these reasons it would be VERY stupid for GB to go to war with the US. It is easier for the US to invade Canada then the other way around due to population differences. The UK has no way of forcing plebiscites in KY or anywhere else. The Union doesn't want to garrison unfriendly states? What the Hell do you think it did during and after the ACW?
a. Doesn't have to be a *huge* base, just an effective one. I'm not saying the Canadians will invade across the Great Lakes nor that the British North Americans will be able to take over the whole country, but the British will be able to use Halifax (and Hamilton) as forward bases to set up a blockade.
b. All the more reason that, should it happen, they'll have the Union pay for it. No one said it was going to be cheap.
c. UK may have an empire to run but if its chief competitor France enters the fray on its side who else has the strength to challenge her Empire? Russia just had a rude wake-up call in the Crimea, the Ottomans are in no shape to do so, the NGF and Italy are still trying to unify their own countries, and Austria-Hungary is working to stay together.
d. GB has food sources form elsewhere, South America is coming into her own and other alternatives are available.
e. London's Exchange will not "instantly crash", they will be hit hard but they will not be knocked out. Again, if there is war and the US does something like seizure and sale, the UK will extract venegance, cash, and soil for her efforts.
f. US forces occupied the South because they saw the war through regardless of price. If they are willing to negotiate peace then it seems clear they are not willing to do that.
g. It would take something serious for the UK to put troops on the ground (different outcome for the Trent affair would do it) but if they decide to step in and recognize the CSA with a mediated peace they can threaten sanctions and embargoes against the US. Depending on how the peace comes down, the UK can force a plebiscite as part of the settlement...or victory. BTW, doesn't the US have a need for nitrates for its gunpowder stocks in 1861/2? Granted, Mammoth Cave in KY can be used, but in order to gear up for greater production it would take time and the nearby Louisvilel and Nashville railway could become a priority target for CS guerillas/raiders.
Snake:
CSA will call for all 11 states in any settlement, the original seven would likely not survive long on their own and the leadership should know that. If that is all they get the CSA will die on the vine likely within 15-20 years with harsh re-integration terms. Even the original 11 states would have trouble although the oil discoveries might help some of that. I would see an Argentina-like nation with almost a Latin American social structure emerging.
Fiver:
I disagree.
*Missouri would probably stay in the Union but a plebiscite would probably still be called as it is a slave state with a star on the Rebel flag via Neosho.
*Maryland would be tough to call early in the war (Note the governor, the arrests, and the relocation of the state assembly in 1861 - the governor himself is an interesting story as is the state's Confederate contribution). I can not honestly say how it goes, it will be close but the Union will push hard to prevent this from happening and might be willing to trade one plebiscite for another, especially in...
*Kentucky would go Confederate by roughly 2:1, its Union support is chiefly located in Louisville and the Ohio River but most of the rest of the state sympathizes with the rebellion. Many of the voters boycotted the 1860 election over the secession issue, resulting in a fairly pro-Union state assembly. They are also not stupid people - many of them decided to provide services to whichever side was passing through and there is little they can do with military forces nearby.
*New Mexico Territory is tough to call, but given how they reacted to Sibley despite everything in 1861, they either get divided or it's a coin toss.
*West Virginia gets dicey also as many of its counties supported secession, but I think Wheeling will join Ohio or Pennsylvania while Harper's Ferry and some of the nearby counties would go to Maryland. Again, it depends on the conditions of the peace.
And yes, the CSA lasted four years under appalling conditions as it was fighting for its existance. The Union will not be destroyed and I doubt she will endure the same conditions for that long. Bringing the UK and France to bear also raises the stakes - the UK will have the force projection capacity to shell Boston, New York City, Philadelphia, and Washington. Whether plausible or not the fear of a British invasion will be in the minds of many in those cities as well, especially the first two.