Playing Both Sides

In any war, there are those that will benefit from the fighting and destruction that it causes. This trope is about when somebody realises this and dupes or manipulates a couple of different groups into fighting each other so that they can turn the chaotic scenario to their advantage.

They could be plotting to take over one of the factions once the war's finished. They could be trying to get one side to change from being a neutral party into an ally or perhaps they are trying to use the situation to look good, making the outsider seem like the reasonable party for their involvement in the conflict. Maybe they just want to use the war as a diversion so they can carry out their own plans. There are many ways to benefit but the crux of the trope is that there is a conflict and somebody has plotted to make that conflict for their own benefit.

Supertrope to Divide and Conquer which is specifically getting groups to fight to wear each other down so that the plotter can conquer them more easily and War for Fun and Profit, when someone plans to make money and gain amusement from the conflict. Related to the Batman Gambit since this trope will often rely on some behaviour predictions and Flaw Exploitation and the Kansas City Shuffle because such a plan is very dependent on misdirection. If the planner can still benefit by the misdirection failing than it could be a Xanatos Gambit. Reference the Fox in Dying Like Animals.

If a leadership of both sides is Playing Both Sides, that's Running Both Sides.

Overlaps with False-Flag Operation.

Anime and Manga

 * Ghost in the Shell: Stand Alone Complex: Kazuondo Gouda plays both sides to incite rebellion in the refugee population of Japan and overthrow the Japanese Government. People would be brainwashed into suicide terrorist attacks on the refugee, then the phenomenon of "Blame the victim" would be stirred up in the main population to bring up resentment against the refugees. Eventually the refugees would be tricked into making an attack to cause the government to hit back and shift to an isolationist and militaristic policy.
 * The plot of the Digimon Frontier movie was this. The villain started a race war to get humanoid Digimon to fight animalistic Digimon to unseal an evil in a can. Notably, the villain was able to pose as the leaders of both military factions.
 * Transformers Armada:, who is manipulating the conflict between the Autobots and Decepticons in order to
 * In One Piece, Crocodile manipulates Alabasta into a civil war.
 * was playing both sides of the Human/Mulian conflict in RahXephon. He helped the Mu develop their Dolems and find ways to work around the dimensional barrier, whilst also setting up TERRA to fight off any Mulian incursions. He didn't really care which side won, as long as it created an environment that would get the RahXephon to activate.
 * Gundam: Anaheim Electronics from the Universal Century timeline is a milder example; they don't try to start wars, but they're more than willing to sell their mobile suits to both sides in a conflict, regardless of any sort of moral complication (like say, the fact that the people they're selling to want to kill half the human population). A prime example of this comes in Mobile Suit Gundam 0083: Stardust Memory: Anaheim builds three Gundams for the Earth Federation, then gladly sells the fourth (modified to look like a Zeon MS) to the Delaz Fleet after the Federation passes on buying it.
 * Haman Karn near the end of Zeta Gundam. When Axis Zeon makes a surprise return in the midst of the Gryps Conflict, both the AEUG and Titans try to get her to join their side. She ends up playing the two against one another so that they'll wipe each other out, leaving Axis as the dominant power in space. It works.
 * Rau Le Creuset of Gundam Seed plays both the Earth Sphere Alliance and ZAFT against each other in the hopes of.

Comic Books

 * Doctor Doom had one where he manipulated two countries, an Aesir worshipping one and Slovakia into a tense state. He then exacerbated things by splitting allegiances within the Avengers on the issue; Thor took the side of his worshippers and the others felt this was wrong of him and sought to oppose him. Then Doom gave Slovakia weapons to attack the other country but then used this as a pretext for his country, Latvaria which neighboured the other two, to intervene (i.e. invade) since the Avengers could not do so unbiasedly.
 * One of Batman's Gambit Roulettes blew up in his face when Stephanie Brown tried to implement it to prove herself after he fired her as Robin. This led to the War Games storyline, wherein Gotham City was consumed in a Mob War that set almost all the city's gangs against one another. Almost all of them-Black Mask stayed out of the melee, fanning the flames until most of his competition had exhausted themselves before he finally struck and united all of Gotham's gangs under his own leadership.

Fan Works

 * In With Strings Attached, John lures a whole bunch of skahs warriors to the Abandoned Warehouse where the Uneasy Alliance of  and the Raleka wizards have stashed the Vasyn. The skahs promptly attack the Raleka guarding the warehouse in an attempt to get in, and the resultant chaos on the ground allows John and Ringo to make the attempt to sneak in via the roof.

Film

 * In Blue Thunder, the heroes discover a conspiracy inside the U.S. government to stir up problems in the Los Angeles barrios by inciting racial tension between whites and Hispanics. They intend to prove the value of the title helicopter by using it to suppress the resulting violence.
 * The Clone War in the Star Wars prequel trilogy is this combined with a masterful Xanatos Gambit. The early stages of the conflict get Naboo's ambassador to the Senate, Palpatine, made into its new Chancellor. Then the escalation prompts the Senate to give Palpatine emergency powers to deal with the Separatists. Of course, should he fail to do so, it's no skin off his back as he's leader of the Separatists too.
 * Yojimbo: In this Akira Kurosawa film, one of the most classic examples of this plot, involves a wandering ronin who, coming across a town dominated by two rival criminal factions, engineers an Enemy Civil War between them, at least partially for kicks.
 * As did A Fistful of Dollars, which was inspired by Yojimbo.
 * And Zatoichi Meets Yojimbo, which was also inspired by Yojimbo.
 * And Last Man Standing, which was also inspired by Yojimbo.
 * And Sukiyaki Western Django, which was inspired by A Fistful of Dollars which was inspired by Yojimbo.
 * Tomorrow Never Dies: This is exactly what Elliot Carver's plan is. He intends to use the impending war between Britain and China to gain exclusive broadcast rights in China for himself, deliberately amping up the tension himself the entire time. The plot is not uncommon in James Bond films: it's also SPECTRE's plan in You Only Live Twice, Stromberg's plan in The Spy Who Loved Me (in both cases to start a nuclear conflict between the US and USSR), and Koskov's plan in The Living Daylights (getting the British and Soviet intelligence agencies to duke it out while he gets away with his scam).
 * Lucky Number Slevin turns a gang warfare into a full-blown Kansas City Shuffle.
 * In Lord of War, arms dealer Simeon Weisz criticizes Villain Protagonist Yuri Orlov for selling weapons to both sides in several conflicts. Orlov points out that Weisz did the same in the Iran-Iraq War, prompting the latter to reply that he wanted "both sides to lose".
 * Tom Reagan in Miller's Crossing plays both sides in a mob war in order to make sure his boss comes out on top.
 * This is rather common in film noir, largely thanks to Dashiell Hammett's works Red Harvest and The Glass Key, which inspired Miller'sCrossing and Brick, among others.

Literature

 * Caleb Trask, in East of Eden took part with his businessman friend Will in war profiteering, buying beans for two cents a pound over fair market value, establishing a monopoly, then selling those beans for more than ten cents a pound over market value several weeks later in the heat of World War!
 * Dashiell Hammett's novel Red Harvest, which was an indirect inspiration for Yojimbo.
 * In Neil Gaiman's American Gods,.
 * The Sum of All Fears contains a plot of this sort in both book and movie form.
 * #9 of The Thirty-Six Stratagems is practically this.
 * Honor Harrington has  doing this to Manticore and Haven for a variety of reasons. Things are starting to come unravelled as of the latest books though.
 * A Song of Ice and Fire: Petyr "Littlefinger" Baelish's preferred Modus Operandi.
 * Comrade Death, a short story by Gerald Kersh, features an Arms Dealer who specializes in this. There are two separate scenes of him selling weapons to one nation only to turn around and sell countermeasures to their enemy immediately after. Ultimately, his company becomes a monopoly and wars fought are entirely supplied by him.
 * The Demolished Man: Ben Reich, the Villain Protagonist, funds both Muggle anti-Esper extremists as well as the more extremist Espers, who want to rule over normal humans. Reich does this because human/Esper cooperation (especially in law enforcement) is a threat to him.
 * The Dragaera novel Jhegaala appears to be inspired by Red Harvest and involves former-assassin Vlad returning to his hometown and finding it a nasty, corrupt place. The two groups responsible for this are a coven of witches and a merchant's guild, and Vlad ultimately plays the two against each other to destroy them both.
 * A Civil Campaign: Byerly Vorrutyer in this Vorkosigan Saga novel is conspiring with both the Richars, and Dono sides in the struggle for who inherits the Vorrutyer Countship, (and telling both sides that he's their spy in the enemy camp.) Whose side he's really on doesn't really become clear until the end.
 * The title character of Mara Daughter of the Nile decides to do this when she finds herself being maneuvered into being a agent of two opposing sides. Then she starts Becoming the Mask and everything starts falling apart.
 * The Gentleman from Adam-Troy Castro's Sinister Six trilogy has spent most of his life doing this, calling himself an investor in chaos.

Live Action TV

 * In Buffy the Vampire Slayer season 4, the part-man, part-demon, part-robot Adam incites violence between soldiers and demons in order to get a big pile of body parts for making more monsters like himself.
 * In the The X-Files episode "Kill Switch", the AI sets up two rival drug gangs to have a shoot out in order to kill the real target, the hacker trying to get at the AI. And that's the AI's sense of humor.
 * In the Doctor Who serial "Frontier in Space", the Daleks exacerbate tensions between Earth and the Draconians, hoping to spark a war that will weaken both sides and allow the Daleks to conquer both empires.
 * Criminal Minds once featured a Charles Manson Expy who intended to spark a race war between Caucasians and Native Americans.
 * Farscape: In season 4, Crichton and his shipmates incite a riot between the techs (Kalish) and soldiers (Charrids) of the bad guys (Scarrans) to cover their escape.
 * In the "Pillows And Blankets" episoce of Community Jeff gives a Rousing Speech to one side of the conflict that lifts their morale and prompts them to go on fighting. We then find out that he gave the same speech to the other side. As long as the conflict is going on, classes are suspended and Jeff does not have to do any school work.
 * In the Modern Family episode "The Last Walt", Haley asks Gloria if she can have a pool party at their house. She overcomes Gloria's resistance by saying she'll have "her uncle" chaperone. Gloria's son Manny, who technically is Haley's uncle even though he's younger than her, only finds out he's the chaperone when the party starts.

Tabletop games

 * Chaos God Tzeentch from Warhammer 40000 definitely qualifies. Although all 4 Chaos gods want to destroy the Imperium, enslave all life, and so on, Tzeentch will often hatch schemes through his followers, then betray said followers. Just because it's fun.
 * Genesteeler cults too: They usually infiltrate and manipulate both the government and dissident groups to cause a continuous world-wide civil war until the hive-fleet arrives.

Video Games

 * In Grand Theft Auto III, Donald Love has the player incite a gang war between the  in order to bring down real estate prices. In Vice City, Avery has Tommy do the exact same thing between the Haitians and the Cubans, with Donald taking notes (they even use the same wording).
 * Bully has Gary orchestrating
 * Halo has two sets of enemies that will happily fight each other. It is possible to engineer a situation where one side narrowly beats the other, allowing Master Chief to mop up the remaining forces.
 * Iji: in several sections of you can take advantage of fighting between Tasen and Komato forces.
 * Fallout 2: Few encounters in are as pleasant as the ones where you meet two groups of gangsters fighting each other. Stay out for the first part, attack one side if it's winning too easily, then wipe out the other side afterwards. Then loot the large number of powerful weapons they drop.
 * Two of the four endings in Fallout: New Vegas revolve around this. When siding with either of the local superpowers, the New California Republic or Caesar's Legion, the player averts this trope. When siding with Mr. House or going rogue, pitting the militarily superior NCR and Legion against each other becomes instrumental. In Mr. House's case, he also wants to make sure that the NCR's defeat is mitigated, as he needs their tourism for his own economy.
 * The Doom series (and the roguelike based on it) has monsters that are programmed to fight one another if you can get them to either blast / wallop each other or if you splash them and trick them into fighting other demons. This allows a player to clear seemingly impossible scenarios, like the room with the Cyberdemon and 18 Barons of Hell. Additionally, some monsters just plain don't like each other, such as the Baron of Hell and the Cacodaemon, a feud lampshaded in the original Doom.

This behavior does not occur in Doom RL. However, the monster AI is incredibly stupid and will happily shoot at you even if there are three or four other monsters in the way who will probably be hit first.
 * Last Scenario and Exit Fate: SCF clearly likes this trope. Both of his freeware RPGs involve it in some fashion.
 * In Modern Warfare 2,
 * In Far Cry 2, the Jackal is engineering a conflict between the two rebel factions by selling weapons to both sides.
 * The first part of Tales of Vesperia revolves around two villains trying to start a war between the Empire and the Guild Union. Though they war is narrowly averted, the tension between the two factions remains a plot point for the remainder of the game.
 * A missing in Final Fantasy XII: Revenant Wings requires you to do this.
 * In Mercenaries, it's generally work for all of the factions, to maximize the amount of money you get and vehicles you can buy. It becomes a careful balancing act once the factions you work for want each other dead.
 * In Silent Storm, when the player first encounters Thor's Hammer, they are supplying the enemy (Allies or Axis, depending on the campaign) with advanced Powered Armor. Then you discover that they're giving those to your side as well. This makes their end-game clear. Cripple both sides, and you can pick up the pieces with technology that neutralizes the Powered Armor advantage.
 * The Kingdom of Loathing "Mysterious Island of Mystery" is inhabited by Frats and Hippies who the Council would like to see wipe each other out in time for the tourist season. Though the Obligatory Pirates remain out of sight during the war you incite, it's possible to get them to strike the finishing blow, bombing them all back to the stone age.
 * Deus Ex Invisible War allows the player to do this between the WTO and The Order.

Webcomics

 * In Order of the Stick the IFCC.
 * Buck Godot: Buck does it in multiple arcs. A great one is at the end of the Psmith arc, where he starts off with playing two sides while both of them are standing right next to him.

Western Animation

 * Aladdin: One episode had Nefir the imp trick the Odifferans into believing that Aladdin had stolen a sacred artifact, so that they would attack Agrabah, and supplied both sides with weapons for an exorbitant fee. Once his intentions were revealed (as was the fact that Nefir himself stole the artifact), both sides threatened Nefir into rebuilding Agrabah and refunding both sides' money.
 * On The Spectacular Spider-Man, Norman Osborn is paid by the Big Man to make supervillains while also getting paid by the police to build those villains' Tailor Made Prisons.
 * In the Looney Tunes short "The High and the Flighty", Daffy Duck is a novelties salesman who supplies for both Foghorn Leghorn and the barnyard dog in their ongoing prank war. He is found out when he accidentally sells them the same gag (the Pipe Full O'Fun Kit No. 7) and decide to team up against Daffy to trap him in his own device.
 * Bob's Burgers: In "Beefsquatch", Bob and Gene have their own cooking segment in a local talk show and try to sabotage each other. They both unknowingly enlist Louise to come up with ways of messing with each other, which she gladly does. Eventually Louise gets disgusted at Bob and Gene's competitiveness and quits.

Real Life

 * War Profiteers in every war ever fought.
 * Numerous countries took aid from both the United States and the Soviet Union during the Cold War.
 * A few wars in Ancient Greece (e.g. The Corinthians during the Peloponnesian War) began with a such a plot. Typically, side A would deviously provoke a proxy of side B to invade one of their own proxies. Side A thus gained a pretext to invade the proxy of side B, prompting side B to declare all-out war on side A. The advantage was that, in the heavily morally charged political climate of Classical Greece, side B would appear to have been the aggressor.
 * Zeno, Emperor of Byzantium, pulled off one of these in A.D. 488 when he induced Theodoric the Great, King of the Ostrogoths, to invade Italy, which was then held by King Odoacer. Both men were nominally servants of the Emperor but actually independent rulers who were constantly causing trouble; by getting them to go to war with each other, Zeno ensured that the Empire would be rid of at least one set of troublemakers, no matter which side won.

Could be considered an instance of Divide and Conquer, except that the Emperor didn't follow up his sucessful gambit (Theodoric won) with a conquest of the Ostrogoths. Although, a few decades later, Justinian did manage to conquer the Ostrogoths and much more.