Many of the classic ballads to which (especially, 19th century) editors or scholars were keen -often at the expense of a good deal of imagination-stretching- to ascribe historical bases show no real sign at all of being based on real, identifiable events (some, indeed, are demonstrably older than the events to which they are popularly supposed to refer) so the subject should be treated with caution, and you shouldn't believe what you're told too readily. I don't think anyone has ever tried to pin this one down to a real event, which suggests that there isn't one. If there had been, you can be sure that extravagant theories would have been built upon it long before now.

Of course, they may have been, and I might just have forgotten, but on the whole I think not.