The Canadian Corps was commanded by Gen. Julian Byng, a Brit who later became Governor General of Canada, until June 1917. Gen. Arthur Currie served under Byng and replaced him as Commander of the Canadian Corps in June 1917. The battle for Vimy took place in April 1917 while Byng was in charge.
http://www.warmuseum.ca/firstworldwar/history/people/generals/sir-julian-byng/