No, I don't mean Yankees, I mean Canadians. Mentioned a book on this topic a wee bit ago; now have it in my possession: Claire Hoy.
From the front flap: "The American Civil War not only subsumed Canadians at every level, it directly determined the shape of Canadian confederation. ... Most Canadians know something about its American impact, but few realize that it also stands as a defining event in Canadian history. Thousands of Canadians fought in the war -- about 5,000 died -- and twice during that period this country, along with Great Britain, came within a whisker of all-out war against Washington."
Over at the 'Civil Warriors' blog, Brooks Simpson calls for "a more sophisticated, thoughtful, and integrated" approach to Civil War studies. I've usually seen the northern front described as a sideshow, yet it appears from this study that a more nuanced story is truer. Today it's the longest undefended border in the world (or at least that's one claim made for it). But a century-and-a-half ago, Canada's connection to Great Britain and its proximity to the northern states like Michigan were a quite different story.
Perhaps the failure to use it more as a staging ground for opening of a second front (ala WWII) should be part of the story on how the Confederacy made some bad military decisions.