Starting Sept. 5, 2014, Genealogy.com will be making a big change. GenForum
message boards, Family Tree Maker homepages, and the most popular articles
will be preserved in a read-only format, while several other features will
no longer be available, including member subscriptions and the Shop.
I have no knowledge of the John Arneil you seek. I am familiar with most or all of the Arniel families around the Kingston, Ontario area, however. The information I have obtained indicates there were three brothers named William, Samuel and Thomas Arniel, all sons of another William Arniel born about 1790 in Ireland. The brothers emmigrated to Kingston, Ont from Ireland about 1860 or so. All three brothers had family, and there were multiple children and grandchildren named William. The particular one I am most interested in, is William Arniel, son of Thomas and Mary Arniel, husband of Anne Matilda Clarke. The WWI war record you referenced is one of these other Williams. I have many census records tracking these particular Arniel families. I also have checked the local cemetaries in Kingston.
Your John Arneil is most likely one of the immigrants from Scotland, which was a more popular Arneil Homeland.