In what way is sir arthur conan doyle’s “the contest” a work of historical fiction?

Note: I haven’t read the book, I read the summary

Historical fiction is when the book is based on historic occurrences though the characters and/or their actions are made-up. “The Contest” is about the Romans and the Roman emperor, Nero. Nero was, in fact, a real person, and the majority is based on actual facts, making it a work of historical fiction.