Interesting discussion. There's no easy answer to the question of number, identity, and motive for "Canadian" involvement. The figure of 50,000 Canadians serving the war has often been used, but there is no definite proof of this that I'm aware of. There were certainly many thousands of men who were born in what is now Canada who were residing in the United States who served in the war. There also must have been thousands of men born outside of Canada who resided there for a significant period of time before moving on (or back) to the United States and then serving. I'm not sure how many actually would have left Canada to volunteer out of conviction or for adventure, but I doubt there were many. Mostly it would have been a matter of money, especially toward the end of the war. This is also when bounty-jumping and crimping became a particularly serious problem.