Alternate history or alternative history is a subgenre of speculative fiction (or science fiction) and historical fiction that is set in a world in which history has diverged from the actual history of the world. Alternate history literature asks the question, "What if history had developed differently?" Most works in this genre are based on real historical events, yet feature social, geopolitical, or industrial circumstances that developed differently than our own. While to some extent all fiction can be described as "alternate history," the subgenre proper comprises fiction in which a change or point of divergence occurs in the past that causes human society to develop in a way that is distinct from our own.
Since the 1950s, this type of fiction has to a large extent merged with science fictional tropes involving cross-time travel between alternate histories or psychic awareness of the existence of "our" universe by the people in another; or ordinary voyaging uptime or downtime that results in history splitting into two or more timelines. Cross-time, time-splitting and alternate history themes have become so closely interwoven that it is impossible to discuss them fully apart from one another.
In French, alternate history novels are called uchronie. This neologism is based on the prefix u- (as in the word utopia, a place that does not exist) and the Greek for time, chronos. An uchronie, then, is defined as a time that does not exist, a "non-time". Another occasionally-used term for the genre is "allohistory" (lit. "other history").
The 1490 epic romance "Tirant lo Blanc", written when the loss of Constantinople to the Turks was still a recent and traumatic memory to Christian Europe, tells the story of the valiant knight Tirant The White from Brittany who gets to the embattled remnant of the Byzantine Empire, becomes a Megaduke and commander of its armies, and manages to fight off the invading Ottoman armies of Mehmet II, save the city from Islamic conquest, and even chase the Turks deeper into lands they had conquered before.
The first novel-length alternate history in English would seem to be Castello Holford's Aristopia (1895). While not as nationalistic as Louis Geoffroy's Napoléon et la conquête du monde, 1812–1823, Aristopia is another attempt to portray a utopian society. In Aristopia, the earliest settlers in Virginia discover a reef made of solid gold and are able to build a Utopian society in North America.
One of the entries in Squire's volume was Churchill's "If Lee Had Not Won the Battle of Gettysburg", written from the viewpoint of a historian in a world where the Confederacy had won the American Civil War, considering what would have happened if the North had been victorious (in other words, a character from an alternate world imagining a world more like the real one we live in, although not necessarily getting all the details right). This kind of speculative work which posts from the point of view of an alternate history is variously known as a "recursive alternate history", a "double-blind what-if" or an "alternate-alternate history".
Another example of alternate history from this period (and arguably the first to explicitly posit cross-time travel from one universe to another as anything more than a visionary experience) is H.G. Wells' Men Like Gods (1923) in which several Englishmen are transferred via an accidental encounter with a cross-time machine into an alternate universe featuring a seemingly pacifistic and utopian Britain. When the Englishmen, led by a satiric figure based on Winston Churchill, try to seize power, the utopians simply point a ray gun at them and send them on to someone else's universe. Wells describes a multiverse of alternative worlds, complete with the paratime travel machines that would later become popular with U.S. pulp writers, but since his hero experiences only a single alternate world this story is not very different from conventional alternate history.
The 1930s would see alternate history move into a new arena. The December 1933 issue of Astounding published Nat Schachner's "Ancestral Voices," quickly followed by Murray Leinster's "Sidewise in Time". While earlier alternate histories examined reasonably straight-forward divergences, Leinster attempted something completely different. In his "world gone mad", pieces of Earth traded places with their analogs from different timelines. The story follows Professor Minott and his students from the fictitious Robinson College as they wander through analogs of worlds that followed a different history.
This period also saw the publication of the time travel novel Lest Darkness Fall by L. Sprague de Camp where an American academic to the Italy of the Ostrogoths at the time of the Byzantine invasion led by Belisarius. De Camp's work is concerned with the historical changes wrought by his time traveler, Martin Padway, thereby making the work an alternate history. Padway is depicted as making permanent changes and implicitly forming a new time branch.
Time travel as the cause of a point of divergence (creating two histories where before there was one, or simply replacing the future that existed before the time traveling event) has continued to be a popular theme: in Bring the Jubilee, by Ward Moore, the protagonist, who lives in an alternate history in which the South won the Civil War, travels through time and brings about a Union victory in the Battle of Gettysburg.
When a story's assumptions about the nature of time travel lead to the complete replacement of the visited time's future rather than just the creation of an additional time line, the device of a "time patrol" is often used. Such an agency has the grim task of saving civilization every day, every hour, with patrol members—depicted most notably in Poul Anderson's "Time Patrol"—racing uptime and downtime to preserve the "correct" history. This is eventually revealed to be the one in which humanity transforms itself into a benevolent super-species that, amongst other achievements, creates time travel to ensure its own existence.
This can lead to terrible moral dilemmas. In Delenda Est, the interference of time-travelling outlaws causes Carthage to win the Second Punic War and destroy Rome. As a result, there is a completely different Twentieth Century — "not better or worse, just completely different". The hero, Patrol Agent Manse Everard, must return to that period, fight the outlaws and change history back, restoring his (and our) familiar history — but only at the price of totally destroying the world which has taken its place, and which is equally deserving of existence. The stakes are the highest imaginable: billions of lives balanced against other billions of lives, for one man to decide. "Risking your neck in order to negate a world full of people like yourself" is how the hero describes what he eventually undertakes.
Also in the late 1940s and the 1950s, however, writers such as H. Beam Piper, Sam Merwin, Jr. and Andre Norton wrote thrillers set in a multiverse in which all alternate histories are co-existent and travel between them occurs via a technology involving portals and/or paratime capsules. These authors established the convention of a secret paratime trading empire that exploits and/or protects worlds lacking the paratime technology via a network of James Bond-style secret agents (Piper called them the "paratime police").
This concept provided a convenient framing for packing a smorgasbord of historical alternatives (and even of timeline "branches") into a single novel, either via the hero chasing or being chased by the villain(s) through multiple worlds or (less artfully) via discussions between the paratime cops and their superiors (or between paratime agents and new recruits) regarding the histories of such worlds.
The paratime theme is sometimes used without the police; Poul Anderson dreamed up the Old Phoenix tavern as a nexus between alternate histories. A character from a modern American alternate history Operation Chaos can thus appear in the English Civil War setting of A Midsummer's Tempest. In this context, the distinction between an alternate history and a parallel universe with some points in common but no common history may not be feasible, as the writer may not provide enough information to distinguish.
Paratime thrillers published in recent decades often cite the many-worlds interpretation of quantum mechanics (first formulated by Hugh Everett III in 1957) to account for the differing worlds. Some science fiction writers interpret the splitting of worlds to depend on human decision-making and free will, while others rely on the butterfly effect from chaos theory to amplify random differences at the atomic or subatomic level into a macroscopic divergence at some specific point in history; either way, science fiction writers usually have all changes flow from a particular historical point of divergence (often abbreviated 'POD' by fans of the genre). Prior to Everett, science-fiction writers drew on higher dimensions and the speculations of P. D. Ouspensky to explain their characters' cross-time journeys.
While many justifications for alternate histories involve a multiverse, the "many world" theory would naturally involve many worlds, in fact a continually exploding array of universes. In quantum theory, new worlds would proliferate with every quantum event, and even if the writer uses human decisions, every decision that could be made differently would result in a different timeline. A writer's fictional multiverse may, in fact, preclude some decisions as humanly impossible, as when, in Night Watch, Terry Pratchett depicts a character informing Vimes that while anything that can happen, has happened, nevertheless there is no history whatsoever in which Vimes has ever murdered his wife. When the writer explicitly maintains that all possible decisions are made in all possible ways, one possible conclusion is that the characters were neither brave, nor clever, nor skilled, but simply lucky enough to happen on the universe in which they did not choose the cowardly route, take the stupid action, fumble the crucial activity, etc.; few writers focus on this idea, although it has been explored in stories such as Larry Niven's All the Myriad Ways, where the reality of all possible universes leads to an epidemic of suicide and crime because people conclude their choices have no moral import.
In any case, even if it is true that every possible outcome occurs in some world, it can still be argued that traits such as bravery and intelligence might still affect the relative frequency of worlds in which better or worse outcomes occurred (even if the total number of worlds with each type of outcome is infinite, it is still possible to assign a different measure to different infinite sets). The physicist David Deutsch, a strong advocate of the many-worlds interpretation of quantum mechanics, has argued along these lines, saying that "By making good choices, doing the right thing, we thicken the stack of universes in which versions of us live reasonable lives. When you succeed, all the copies of you who made the same decision succeed too. What you do for the better increases the portion of the multiverse where good things happen." This view is perhaps somewhat too abstract to be explored directly in science fiction stories, but a few writers have tried, such as Greg Egan in his short story The Infinite Assassin, where an agent is trying to contain reality-scrambling "whirlpools" that form around users of a certain drug, and the agent is constantly trying to maximize the consistency of behavior among his alternate selves, attempting to compensate for events and thoughts he experiences but he guesses are of low measure relative to those experienced by most of his other selves.
Many writers — perhaps the majority — avoid the discussion entirely. In one novel of this type, H. Beam Piper's Lord Kalvan of Otherwhen, a Pennsylvania State Police officer, who knows how to make gunpowder, is transported from our world to an alternate universe where the recipe for gunpowder is a tightly held secret and saves a country that is about to be conquered by its neighbors. The paratime patrol members are warned against going into the timelines immediately surrounding it, where the country will be overrun, but the book never depicts the slaughter of the innocent thus entailed, remaining solely in the timeline where the country is saved.
The cross-time theme was further developed in the 1960s by Keith Laumer in the first three volumes of his Imperium sequence, which would be completed in Zone Yellow (1990). Piper's politically more sophisticated variant was adopted and adapted by Michael Kurland and Jack Chalker in the 1980s; Chalker's G.O.D. Inc trilogy (1987–89), featuring paratime detectives Sam and Brandy Horowitz, marks the first attempt at merging the paratime thriller with the police procedural. Kurland's Perchance (1988), the first volume of the never completed "Chronicles of Elsewhen", presents a multiverse of secretive cross-time societies that utilize a variety of means for cross-time travel, ranging from high-tech capsules to mutant powers. Harry Turtledove has launched the Crosstime Traffic series for teenagers featuring a variant of H. Beam Piper's paratime trading empire.
The concept of a cross-time version of a world war, involving rival paratime empires, was developed in Fritz Leiber's Change War series, starting with the Hugo Award winning The Big Time (1958); followed by Richard C. Meredith's Timeliner trilogy in the 1970s, Michael McCollum's A Greater Infinity (1982) and John Barnes' Timeline Wars trilogy in the 1990s.
Such "paratime" stories may include speculation that the laws of nature can vary from one universe to the next, providing a science fictional explanation—or veneer—for what is normally fantasy. Aaron Allston's Doc Sidhe and Sidhe Devil take place between our world, the "grim world" and an alternate "fair world" where the Sidhe retreated to. Although technology is clearly present in both worlds, and the "fair world" parallels our history, about fifty years out of step, there is functional magic in the fair world. Even with such explanation, the more explicitly the alternate world resembles a normal fantasy world, the more likely the story is to be labeled fantasy, as in Poul Anderson's "House Rule" and "Loser's Night."
In both science fiction and fantasy, whether a given parallel universe is an alternate history may not be clear. The writer might allude to a POD only to explain the existence and make no use of the concept, or may present the universe without explanation to its existence.
It was followed by Vladimir Nabokov's Ada or Ardor: A Family Chronicle (1969), a story of incest that takes place within an alternate North America settled in part by Czarist Russia, and that borrows from Dick's idea of "alternate-alternate" history (the world of Nabokov's hero is wracked by rumors of a "counter-earth" that apparently is ours). Some critics believe that the references to a counter-earth suggest that the world portrayed in Ada is a delusion in the mind of the hero (another favorite theme of Dick's novels). Strikingly, the characters in Ada seem to acknowledge their own world as the copy or negative version, calling it "Anti-Terra" while its mythical twin is the real "Terra." Not only history but science has followed a divergent path on Anti-Terra: it boasts all the same technology as our world, but all based on water instead of electricity. When a character in Ada makes a long-distance call, all the toilets in the house flush at once to provide hydraulic power.
Isaac Asimov's short story "What If—" is about a couple who can explore alternate realities by means of a television-like device. This idea can also be found in Asimov's 1955 novel The End of Eternity. In that novel, the "Eternals" can change the realities of the world, without people being aware of it.
The Plot Against America (2004) by Philip Roth looks at an America where Franklin D. Roosevelt is defeated in 1940 in his bid for a third term as President of the United States, and Charles Lindbergh is elected, leading to increasing fascism and anti-Semitism in the U.S.
In the Darren Shan Books "The Saga of Darren Shan" this subject is addressed in the twelfth book. It is said that history cannot be changed claiming that even if you went back in time and killed Adolf Hitler someone else would just replace him. A similar message is given in the German writer Carl Amery's book, The Royal Project (German: Das Königsprojekt), where a special unit of the Pope's Swiss Guard tries to change history in the Catholics' favor but comes to realize that, while history can be manipulated, it can not be changed.
The late 1980s and the 1990s saw a boom in popular-fiction versions of alternate history, fueled by the emergence of the prolific alternate history author Harry Turtledove, as well as the development of the steampunk genre and two series of anthologies — the What Might Have Been series edited by Gregory Benford and the Alternate ... series edited by Mike Resnick. This period also saw alternate history works by S.M. Stirling, Kim Stanley Robinson, Harry Harrison, Howard Waldrop and others.
Since the late 1990s, Harry Turtledove has been the most prolific practitioner of alternate history and has been given the title "Master of Alternate History" by some. His books include the Timeline-191 series, in which Confederate States of America won the American Civil War, and the Tosev timeline series, in which aliens invaded Earth during World War II. Other stories by Turtledove include A Different Flesh, in which America was not colonized from Asia during the last ice age; In the Presence of Mine Enemies, in which the Nazis won World War II; and Ruled Britannia, in which the Spanish Armada succeeded in conquering Britain in the Elizabethan era, with William Shakespeare being given the task of writing the play that will motivate the Britons to rise up against their Spanish conquerors. He also co-authored a book with actor Richard Dreyfuss The Two Georges, in which the United Kingdom retained the American colonies, with George Washington and King George III making peace. He did a two-volume series in which the Japanese not only bombed Pearl Harbor but also invaded and occupied the Hawaiian Islands.
Perhaps the most incessantly explored theme in popular alternate history focuses on worlds in which the Nazis won World War Two. In some versions, the Nazis conquer the entire world; in others, they conquer most of the world but a "Fortress America" exists under siege. Fatherland (1992) by Robert Harris, set in Europe following the Nazi victory, has been widely praised for portraying a more believable society and series of events than most other novels set in a world after a Nazi victory. Several writers have posited points of departure for such a world but then have injected time splitters from the future or paratime travel for instance James P. Hogan's The Proteus Operation. Norman Spinrad wrote The Iron Dream in 1972, which is intended to be a science fiction novel written by Adolf Hitler after fleeing from Europe to North America in the 1920s. Former House Speaker Newt Gingrich and William R. Forstchen have written a novel, 1945, in which the U.S. defeated Japan but not Germany in World War II, resulting in a Cold War with Germany rather than the Soviet Union. Gingrich and Fortschen neglected to write the promised sequel; instead, they wrote a trilogy about the American Civil War, starting with Gettysburg: A Novel of the Civil War, in which the Confederates win a victory at the Battle of Gettysburg.
Beginning with The Probability Broach in 1981, L. Neil Smith wrote several novels which postulated the disintegration of the U.S. Federal Government during the Whiskey Rebellion and the creation of a libertarian utopia.
A recent time traveling splitter variant involves entire communities being shifted uptime to be the founding fathers of new time branches. These communities are transported either from the present or the near-future to the past via a natural disaster, the action of technologically advanced aliens, or a human experiment gone wrong. S.M. Stirling wrote the Island in the Sea of Time trilogy, in which Nantucket Island and all its modern inhabitants are transported to Bronze Age times to become the world's first superpower. In Eric Flint's 1632 series, a small town in West Virginia is transported to 17th century Europe and leads a revolution against the Habsburgs. John Birmingham's Axis of Time trilogy deals with the culture shock when a United Nations naval task force from 2021 finds itself back in 1942 helping the Allies against the Empire of Japan and the Germans (and doing almost as much harm as good in spite of its advanced weapons).
Many fantasies and science fantasies are set in a world that has a history somewhat similar to our own world, but with magic added. Since the existence of magic implies different laws of nature it is difficult to imagine a credible point of divergence: The effects of divergence would have existed throughout human history and indeed throughout all evolution of life (unless one posits sudden changes in the laws of nature in medieval or modern times brought about by aliens, a time-space warp, etc.). One example of a universe that is in part historically recognizable but also obeys different physical laws is Poul Anderson's Three Hearts and Three Lions in which the Matter of France is history, and the fairy folk are real and powerful. A partly familiar European history for which the author provides a point of divergence is Randall Garrett's "Lord Darcy" series: a monk systemizing magic rather than science, so the use of foxglove to treat heart disease is called superstition.
Jonathan Strange & Mr Norrell takes place in an alternate version of England where a separate Kingdom ruled by the Raven King and founded on magic existed for in Northumbria for over 300 years. In Patricia Wrede's Regency fantasies, Great Britain has a Royal Society of Wizards, and in Poul Anderson's A Midsummer Tempest William Shakespeare is remembered as the Great Historian, with the novel itself taking place in the era of Oliver Cromwell and Charles I—and an earlier Industrial Revolution.
The Tales of Alvin Maker series by Orson Scott Card (a parallel to the life of Joseph Smith, Jr., founder of The Church of Jesus Christ of Latter-day Saints) takes place in an alternate America, beginning in the early 19th century. Prior to that time, a POD occurred: England, under the control of Oliver Cromwell, had banished "makers", or anyone else demonstrating "knacks" (an ability to perform seemingly supernatural feats) to the North American continent. Thus the early American colonists embraced as perfectly ordinary these gifts, and counted on them as a part of their daily lives. The political divisions of the continent is considerably altered, with two large English colonies bookending a smaller "American" nation, one aligned with England, and the other governed by exiled Cavaliers. Actual historical figures are seen in a much different light: Ben Franklin is revered as the continent’s finest "maker", George Washington was executed at the hands of an English army, and "Tom" Jefferson is the first president of "Apallachee", the result of a compromise between the Continentals and the British.
On the other hand, when the "Old Ones" still manifest themselves in England in Keith Roberts's Pavane, which takes place in a technologically backward world after a Spanish assassination of Elizabeth I allowed the Spanish Armada to conquer England, the possibility that the fairies were real but retreated from modern advances makes the POD possible: the fairies really were present all along, in a secret history. Again, in the English Renaissance fantasy Armor of Light by Melissa Scott and Lisa A. Barnett, the magic used in the book, by Dr. John Dee and others, actually was practiced in the Renaissance; positing a secret history of effective magic makes this an alternate history with a POD, Sir Philip Sidney's surviving the Battle of Zutphen, and shortly there after saving the life of Christopher Marlowe.
Many works of fantasy posit a world in which known practitioners of magic were able to make it function, and where the consequences of such reality would not, in fact, disturb history to such an extent as to make it plainly alternate history. Many ambiguous alternate/secret histories are set in Renaissance or pre-Renaissance times, and may explicitly include a "retreat" from the world, which would explain the current absence of such phenomena.
When the magical version of our world's history is set in contemporary times, the distinction becomes clear between alternate history on the one hand and contemporary fantasy, using in effect a form of secret history (as when Josepha Sherman's Son of Darkness has an elf living in New York City, in disguise) on the other. In works such as Robert A. Heinlein's Magic, Incorporated where a construction company can use magic to rig up stands at a sporting event and Poul Anderson's Operation Chaos and its sequel Operation Luna, where djinns are serious weapons of war — with atomic bombs — the use of magic throughout the United States and other modern countries makes it clear that this is not secret history—although references in Operation Chaos to degaussing the effects of cold iron make it possible that it is the result of a POD. The sequel clarifies this as the result of a collaboration of Einstein and Planck in 1901, resulting in the theory of "rheatics". Henry Moseley applies this theory to "degauss the effects of cold iron and release the goetic forces." This results in the suppression of ferromagnetism and the reemergence of magic and magical creatures.
Alternate history shades off into other fantasy subgenres when the use of actual, though altered, history and geography decreases, although a culture may still be clearly the original source; Barry Hughart's Bridge of Birds and its sequels take place in a fantasy world, albeit one clearly based on China, and with allusions to actual Chinese history, such as the Empress Wu. Richard Garfinkle's Celestial Matters incorporates ancient Chinese physics and Greek Aristotelian physics, using them as if factual.
A fantasy version of the paratime police was developed by children's writer Diana Wynne Jones in her Chrestomanci quartet (1977–1988), with wizards taking the place of high tech secret agents. Among the novels in this series, Witch Week stands out for its vivid depiction of a history alternate to that of Chrestomanci's own world rather than our own (and yet with a specific POD that turned it away from the "normal" history of most worlds visited by the wizard).
Terry Pratchett's works includes several references to alternate histories of Discworld. Men At Arms observes that in millions of universes, Edward d'Eath became an obsessive recluse rather than the instigator of the plot that he is in the novel. In Jingo, Vimes accidentally picks up a pocket organizer that should have gone down another leg of the Trousers of Time, and so can hear the organizer reporting on the deaths that would have occurred had his decision gone otherwise. Indeed, Discworld contains an equivalent of the Time Patrol in its History Monks. Night Watch revolves around a repair of history after a time traveler's murder of an important figure in Vimes's past. Thief of Time presents them functioning as a full-scale Time Patrol, ensuring that history occurs at all.
The idea of an alternate history was used for satiric and comedic effect in the BBC Radio comedy Married. The protagonist, a confirmed bachelor, awakes one morning in a world where he has a wife and two children, and people familiar to him are radically changed. One historical divergence in this world, exploited mostly for comedy, was the decision of King Edward VIII not to abdicate in 1936. His heirs were a King Richard and a King John, the latter of whom was openly homosexual.
A few movies about alternative universes focus on individuals rather than historical events, for example, Frank Capra’s It's a Wonderful Life, and more recently the Back to the Future series of films, Blind Chance, Sliding Doors, Run Lola Run, Me Myself I, The Butterfly Effect, and Frequency.
Other non-alternate history television shows have explored the concept. Star Trek has used the theme several times. Examples include: TOS- "City on the Edge of Forever" (alternate World War II outcome); Animated Series- "Yesteryear"; NG- "Yesterday's Enterprise". Also, the universe of "Mirror, Mirror", while in the original episode was just implied to be a parallel universe, was in later episodes shown to be an alternate history. The British TV series Doctor Who had a few episodes that involved an alternate Earth where Pete Tyler, father of Rose Tyler, was alive, successful, and rich, unlike the Pete Tyler on the original Earth, who died when Rose was a baby and had been unsuccessful in business. The Doctor, Rose, and Mickey Smith visited the alternate Earth by accident in Rise of the Cybermen and The Age of Steel. The second season finale Army of Ghosts and Doomsday also involved travel to the same alternate Earth, and the series four episode Turn Left showed an alternate history where the Doctor has been killed. On a 2007 episode of Family Guy, Peter Griffin travels back to 1984 to meet Lois when they were both 18, and ends up not going to the country club dance and then in the present was radically changed. In the Twilight Zone episode The Parallel, an astronaut is transported to an alternate Earth where history play our differently, but no-one believes him when he discovers this.
Various anime productions have also used the genre. In the Japanese television series, "Zipang" (based on a manga of the same name), a modern Aegis class destroyer of the Japan Maritime Self-Defense Force is thrown back in time to the Battle of Midway in 1942. The presence of the ship and its crew, their advanced technology and knowledge of the future, change the course of World War II and create an alternate timeline. The anime Code Geass depicts an alternate history in which an empire known as Britannia has colonized Japan.
Crimson Skies is one example of an alternate history spawning multiple interpretations in multiple genres. The stories and games in Crimson Skies take place in an alternate 1930s United States, where the nation crumbled into many hostile states following the effects of the Great Depression, the Great War, and Prohibition. With the road and railway system destroyed, commerce took to the skies. Great cargo zeppelins escorted by fighter squadrons are the targets of many ruthless air pirates and enemy countries. This world has featured in a board game, a PC game, an Xbox game, a collectible miniature game and various promotional novels, comics and short stories.
The game Freedom Fighters portrays a situation similar to that of the movie Red Dawn and the game Red Alert 2, though less comically than the latter. In it, the point of divergence is during World War II, with the Soviet Union first to develop an atomic weapon, which they immediately use on Berlin. With the balance of power and influence tipped in Russia's favor, history diverges; brief summaries at the beginning of the game inform the player of the Communist bloc's complete takeover of Europe by 1953, a different ending to the Cuban Missile Crisis, and the spread of Soviet influence into South America and Mexico. The plot of the game revolves around a Soviet invasion of the United States and the resistance fighting in New York City.
Similarly, the 2007 video game World in Conflict is set in 1989, with the Soviet Union on the verge of collapse. The point of divergence is several months before the opening of the game, when Warsaw Pact forces staged a desperate invasion of Western Europe. As the game begins, a Soviet invasion force lands in Seattle, taking advantage of the fact that most of the military is in Europe. The game is divided into three parts: the first focuses on the fighting retreat from Seattle towards Fort Teller in the Cascade Mountains; the second is a flashback to the recent fighting in Europe, which culminated in a Soviet attack on Manhattan; the third chronicles the fight to retake Seattle before a Chinese fleet arrives and forces the President to detonate a nuclear weapon to destroy the invaders. Turning Point: Fall of Liberty, released in February 2008, is an alternate history game in which Winston Churchill died in 1931, Europe and North Africa fell to the Nazis, and the Axis won World War II and have invaded the United States. Another alternate history game involving Nazis is War Front: Turning Point in which Adolf Hitler died during the early days of World War II and thus, a much more effective leadership rose to power. Under the command of this new Führer (who is referred to as "Chancellor", and his real name is never revealed), Operation Sealion succeeds and The Nazis successfully conquer Britain, sparking a cold war between the Allied Powers and Germany.
Another example of alternate history is the PS3 game Resistance: Fall of Man, in which World War II didn't happen, due to the absence of American forces in World War I, meaning there was no Great Depression or Treaty of Versailles. This explains the game's lack of nuclear offensive capabilities against the Chimera, an army of humans infected by an alien virus.
Influential comic writers have also used an alternate history as the background to their story. Alan Moore's 1986 comic series Watchmen is set in an alternate United States that not only has costumed adventurers but also contains other alternate history elements including an American "victory" in the Vietnam War and Richard Nixon serving five terms as president. Recently there has been Warren Ellis's 2001 comic series Ministry of Space where soldiers and operatives of the United Kingdom reached the German rocket installations at Peenemünde ahead of the U.S. Army and the Soviets.
The major comic book publishers have also used an alternate history. DC Comics referred to such stories as "Imaginary Tales" until in 1989 with Batman: Gotham by Gaslight they began using its publication imprint, Elseworlds. Various titles have been published under the Elseworlds logo including JLA: The Nail, , and Kingdom Come. Some Elseworlds titles have also appeared in the DC Comics Multiverse as alternate Earths with their character interacting with the character from the canon Earth. Marvel Comics has a similar format with their What If...? series. Beginning in 1977, the comics are usually single issues that are not connected to the main story line. A recent example is What If?: Planet Hulk which was based on the 2006 Planet Hulk crossover story line.
The basic difference between alternate history and a future history which becomes a kind of alternate history retrospectively is that the former is composed with the author in possession of facts on the course of actual events to which an alternate is posited, while the latter is written by a person having no knowledge of the future and who tries, to the best of his or her ability, to extrapolate from known tends at the time of writing. For example, H.G. Wells in "The Shape of Things to Come" - written in 1933 when Germany was still enfeebled by the Versailles Treaty and Adolf Hitler has just taken power - assumed that in the coming war, Poland would prove Germany's match militarily and the two would fight each other for ten years without a clear victory to either. A present-day writer - already in possession of the knowledge that Poland was swiftly overwhelmed by the Wehrmacht in the opening stage of the war - would, in order to write a similar alternate World War II scenario, need to give the reader a detailed explanation accounting for such a better performance by the Poles.
One should also not confuse the alternate history subgenre with secret history or historical revisionism, which gives an account of history at odds with our general understanding. For instance, a story that depicts key events of U.S. history as having been controlled by the Illuminati, Freemasons, or aliens might be secret history. Writers occasionally do unite alternate history and secret history. One example is "Dukakis and the Aliens," by Robert Sheckley in which Michael Dukakis defeats George H. W. Bush for the presidency in 1988 and then is taken to a secret saucer base under Area 51 to meet his new masters.
Alternate history also should not be mistaken for fantasy tales that employ a lost history trope, i.e., that assume a stage of human civilization which supposedly has been forgotten through the passage of time, not through conspiratorial suppression. The works of Robert Howard and J.R.R. Tolkien are excellent examples of lost history, which generally does not purport to represent a different timeline from our own. This type of history is generally referred to as Uchronia.
It is also possible to have novels that explore points of divergence without actually being works of alternate history themselves. An example includes Marge Piercy's Woman on the Edge of Time (1976). In the Piercy book, which follows Williamson's basic concept, a patient in a mental hospital is able to travel into two alternate futures—one an ecotopia run by reformed Weather Underground types and the other a fascist dystopia run by people-hating robots. Decisions she must make to resist a new type of brain operation will determine which future wins. This is a time travel story, a cross-time story, a delusional alternate reality story, and a point of divergence story all rolled into one but it is not alternate history because the point of divergence occurs in the present (or perhaps the near future), not in the past.
Less obvious is the difference between alternate history and invasion literature. The latter subgenre extrapolates, from the present, a concrete near-future possibility that is often an expression of current public fears (hence the alternate term "cautionary tale" used by Vita Sackville-West; see below). For instance, beginning in the 1870s the British reading public was treated to a number of books about a German or French invasion of an unready British Isles. During the Great Depression, Sinclair Lewis wrote of a fascist takeover in the United States in his classic It Can't Happen Here (1935). During the early years of World War II, Sackville-West penned the science fantasy Grand Canyon (1942) in which the Germans invade a woefully unprepared United States. One could define such tales as borderline alternate history, since they are usually set in a time that is only shortly after the time of writing and the events described could not have occurred without a branching of history before, if only slightly before, the book was written.
Not all time travel stories involve alternate histories. The writer may ignore the possibility of change, or have the cause-and-effect work out so that the time traveler's actions cause the future he remembers, as in Harry Harrison's The Technicolor Time Machine. Another example of this approach is Michael Moorcock's Behold the Man, in which the protagonist travels back to the Holy Land of 28 AD to meet Jesus, but upon meeting him (he is actually a retarded man) he starts to play the role of the Jesus he knows to the point that it is he who ends up dying in the cross.