Bill, from what I've seen on the Google site for John Allen and the Battle of Frenchtown, on the River Raisin, I believe that the elder John was the one that died there and had counties in three states named for his honor.
My great grandfather was born in Montgomery County, KY. in 1835, but I haven't a clue to who his parents were.
You may want to contact : email@example.com
on his web site, he seems to be trying to track down the same John Allen that you are searching for !
Good luck, and best regards .................Dave.