The Lower Canada Rebellion, the Upper Canada Rebellion, the Red River Rebellion and Quebec's Quiet Revolution come to mind, but they don't constitute the sort of "civil war" under consideration here. Had Canada gone through such a national trauma, I wonder if the end result would have been the division of Canada into 3 separate nations: Quebec, a Maritime Union plus one composed of everything else between Ontario and British Columbia and including the NW+Yukon Territories, rather then a reconciliation as (over time) happened in the US.
I did a quick google search for
Canada civil war and found this interesting article on
Why Was There No Canadian “Civil War”?:
http://www.mises.ca/posts/articles/why-was-there-no-canadian-civil-war/ After reading it, it seems that the 1870s would have been a good time period for one to have occurred.