And now for the "Union would win anyway" derail ...
If no other European power intervenes or runs interference for the Union the Union loses, hard.
I mean, Louis Napoleon III is a retard, but if the British could get him to concentrate forces into Quebec and hit from there then that will improve French chances.
The British and the French can attack from several directions over land as well as over sea.I do not know how the Union's industry is distributed but I'd assume that some of it would already be focused around the Great lakes region and/or in places like New York, with their convenient ports and lots of incoming immigrants that can serve as a workforce.
A combination of blockades, hit and run attacks and a few large offensives will tear the North apart, especially if they also bolster the confederacy and turn the South into a huge meatgrinder that can bloody the North and eat up their manpower and resources.
@bintananth what form would the South's government take and how much time will it take it to be "persuaded" by its new friends to emancipate the slaves?
What will happen with them?
Will they be as hated as they were in OTL, more hated, less hated since they will not be seen as the reason why the South was smashed?
In many countries that retained slavery, the slave owners were compensated by the government for the emancipation, so maybe between winning the war and getting financial compensation there might not be as much racial animosity and crap like the KKK.
Also, how independent will the Confederate government be?
I'd think that they will basically be an Anglo-British puppet that is heavily dependent on its patrons.
Will the Union be forced to cede to Britain and France territory?
Since it would have been damaged severely and vanquished, will it even exist?