Negro troops were instrumental in building the AlCan Highway. I've read one memoir where the writer asserts that they were sent on this job because it was believed they'd freeze to death faster than white troops, thus getting rid of them. No support was offer for this, but it rings true for some people.
I'm sorry they didn't go into more detail about this: "Kathy Brooks says her ancestors were slaves who escaped to Canada through the Underground Railroad. Shepherd's father and grandmother eventually settled on a family farm in Stewarttown, near Georgetown."
There is a letter written by a Canadian soldier in the Ypres area in the first world war who wrote of a sing song which included "Dixie" and some of the Minstrel songs and a black Canadian soldier remarked he was far happier above the 49th Parallel and he had no intention of visiting the land of cotton. Canadian units also has some native Americans who fought with distinction