Kate Hill's guest blog inspired me to some thoughts about the Alternate History subgenre. Two of my favorite series fall into that category, S. M. Stirling's DIES THE FIRE universe (as well as his stand-alone novel THE PESHAWAR LANCERS, with one related novella) and Naomi Novik's Temeraire series (Napoleonic War with aviators on flying dragons). Alternate history has gained new popularity in recent years with the rise of steampunk. If not set in an author-created secondary world, steampunk stories are usually alt-hist versions of the Victorian era. One of my favorite vampire authors, P. N. Elrod, recently released a novel in that subgenre, THE HANGED MAN, featuring a female psychic investigator in a nineteenth-century England somewhat different from our own. Neil Gaiman's delightfully bizarre short work "A Study in Emerald" places a Sherlock Holmes spinoff in an alternate nineteenth century where eldritch Lovecraftian entities have taken over the world, with Queen Victoria herself one of them. Human society muddles along well enough under the allegedly benign rule of the Great Old Ones, but resistance movements do exist. I'm also a big fan of Kim Newman's ANNO-DRACULA and its sequels, in which British and European history as we know it takes a dark twist when Count Dracula, instead of being slain by Van Helsing and company, defeats them and forcibly marries the Queen, thus becoming Prince Consort and de facto ruler of the realm.
I agree with Kate that an advantage of alternate history fiction is its visible connection with our own world. I confess I started to lose interest in Stirling's "Island in the Sea of Time" trilogy, well-written and engaging though it is, when the characters (thrown back thousands of years by an Event that transported the entire island of Nantucket through time) sailed to the Mediterranean region in the Bronze Age and commenced altering the entire future history of Earth, potentially beyond recognition. Good story, but a different kind of story.
Alternate history should be distinguished from what's often called "secret history," in which the publicly acknowledged events of the past aren't changed, but major influences act behind the scenes to subvert the truth as we know it. For example, in Katherine Kurtz's TWO CROWNS FOR AMERICA, occult forces on both sides conspire to support or undermine the American Revolution, with the full knowledge of George Washington and other leading figures of the time. The eighteenth-century flashbacks in the TV series SLEEPY HOLLOW fall into the same category.
How close the point-of-departure falls to our own time heavily affects how far the result will differ from our timeline. Consider how much time the "butterfly effect" has in which to operate. For instance, the twenty-first century in the world of Stirling's "Island" trilogy, after thousands of years of divergent development, would look hardly anything like ours. On the other hand, Jo Walton's "Small Change" trilogy (beginning with FARTHING), eight years after England made peace with Germany early in World War II, reveals Europe under Nazi rule and Britain leaning toward fascism, but the setting has recognizable similarities to our own 1950s. Speaking of Nazis, Norman Spinrod's rather odd novel THE IRON DREAM takes a metafictional approach to twentieth-century history. The book is framed as a commentary on a book-within-the-book, a science fiction novel written by a minor German author named Adolf Hitler, who failed as an artist and, instead of entering politics, moved to the U.S. and became a writer. So authors can create many different types of "gateways" into alternate histories.
The further in the past your point-of-departure occurs, the less likely it is that any historical characters from our own timeline will exist in the alternate world. After all, a day's difference in the date of a baby's conception would result in a different individual, because a different sperm cell would fertilize the egg. "Butterfly" one such timing change into millions. Those historical characters often show up anyhow, though, because it's just more fun that way. I'm perfectly willing to suspend disbelief in order to enjoy spotting parallel-world incarnations of real-life statesmen, generals, authors, and other notable figures.
Near-future science fiction involuntarily morphs into alternate history when overtaken by real-world events. Heinlein turned this inevitable development to his advantage in his Future History series. In his later novels, he establishes that the books in this "history" represent only one of many different timelines in the development of twentieth-century Earth.
Check out Uchronia, a website on alternate history with a huge bibliography:Uchronia
Merry Christmas and Happy Yuletide!
Margaret L. CarterCarter's Crypt