Sorry mate, but I completely disagree with you.
New England isn't exactly that far from Canada now, is it? Imagine if Boston and New York had fallen to the British?
And Warrior was much faster than Monitor, on engines alone. Over double its speed with sails too. Was also armed with 10 7 inch guns and 4 40 pounders, one shot, one kill on a Monitor class. (I realise the Monitor class wasn't the only ironclad type used by the Union Navy, but its a benchmark).
You realise this was the time of Britain's complete supremacy on the global scene (sadly lost, I lament), population levels on par with the US and a much more efficient and advanced manufacturing sector.
And lets not forget the French.
I don't think the Union would've lasted long