American who served in the Canadian Artillery

[brianmorris547]

I wonder if one of our Canadian friends can help me please. My cousin has found a letter written to my great grandmother in Bolton from her niece Grace K Duffy of 48 Wayne Ave, Paterson NJ. It is dated 09/11/1918. She talks of her cousin, Joe, who enlisted when the USA entered the war but was rejected. He then went to Canada and enlisted into the Canadian Field Artillery. He sailed for England in November 1917 and arrived in France in June 1918. His name was possibly Joe or Joseph Duffy but we cannot be certain of the surname. My cousin wants to know his surname for her family research. Could someone please check if there was a soldier of this name, who was an American, in the Canadian Artillery.

Thank you

Brian