Jennifer, an excellent place to start is the National Archives of Canada the site address is www.archives.caThey have a lot of info on how to obtain military records for family members. There are certain restrictions. It sounds like your great uncle was an american serving for Canada. This was very common as Canada entered WW2 with the British Commonweatlh in 1939. Most Canadians served from 1939 until 1945. Alot of americans did serve and continued to serve even after the US joined. Hope this helps.