In this case it seems as if the appeal of a good yarn is not consistent with the facts. There were actually two fighters named Jack Dempsey: one in the 19th century and the other (and more famous) in the 20th century. The earlier Jack Dempsey was born in 1862 (in Ireland) and, thus, would have been only a boy at this time (about 1867). Since the later Jack Dempsey wasn't born until 1895, the events described here would have taken place before he was born. Hence, neither Jack Dempsey could have been involved in this event..

It is possible that Frank witnessed a fight like this but that it involved another boxer. It is more likely that the poetic appeal of the story was too good to pass up, whether or not it actually happened. At this point it is not possible to know what the truth might be.