Start X to Stop X

"Si vis pacem para bellum"

- Latin adage, translated as "If you wish for peace, prepare for war"

So, you have an idea, it's beautiful and you want to fulfill it. Let's say, for example, you want peace. So, how are you going to fulfill it? Fight a war.

Put it basically, you're doing the exact opposite of what you're trying to fulfill.

This comes in two setups, but leads down to the same point:
 * 1) You want to fulfill X, so you do Y, which is completely opposite to X. (the page quote)
 * 2) You want to stop X, so you do X. (For example, you want to stop war, so you start a war, so when you finish it, you can disarm everyone)

As hypocritical as it may sound, sometimes this is the only possible choice, and some people will even acknowledge it.

Some will know this with the phrase "Fight fire with fire", which this trope is (in Setup 2), but this tropes also includes the ideology of the action, not just the methods alone, but, of course, it's not totally necessary to have the ideology to back it up.

Anime & Manga

 * Many Gundam villains.
 * The protagonists of Mobile Suit Gundam 00 seek to end global conflict by attacking anyone who causes military aggression.
 * Gundam Wing has Zechs desire to cause such intense devastation to Earth that war loses all appeal. In Endless Waltz this is partially the reason Wufei switches sides and fights against the Gundam Pilots, which is explained more in supplimentary materials.
 * Bleach: To fight high-level Hollows, some Shinigami don Hollow masks (becoming Vizards.) To fight high-level Shinigami, some Hollow take their masks off (becoming Arrancars.)
 * Notable in that none of the Vizards . Currently,.
 * Code Geass plays this one very straight. Early in the second season, Zero publicly admits that he became evil because he was convinced it was the only way to defeat the evil Britannian empire.
 * Pain from Naruto, who wants to end all wars by giving people the ultimate weapon of mass destruction.
 * Crest of the Stars The Ahb take the position that humanity will be inevitably be destroyed in a galactic war if left to themselves. So they decide to conquer everyone and incorporate them into their Empire, denying all other races the ability of hyperspace travel so that there won't be any war. Tactics used to accomplish this salvation include blowing away the atmosphere of rebellious planets. And they're the protagonists!
 * Light Yagami of Death Note commits mass homicide in order to put an end to all crime.
 * In episode 21 of Genesis of Aquarion, Sirius declares that "the reason I fight is to create a world free of fighting, where beauty prevails."
 * Paradox from the Yugioh Tenth Aniversary Movie wants to use Duel Monsters to Stop Duel Monsters from being made.
 * Chris from Senki Zesshou Symphogear uses her heavily armed Powered Armor to end wars and fighting by beating thouroughly anyone armed at all.

Comic Book

 * Watchmen: in order to stop people from killing each other,.
 * DC One Million: in order to stop plot to destroy the past, the heroes have to

Literature

 * Frindle combines this with Reverse Psychology. A young boy is trying to popularize the term "frindle" as an alternative for "pen,"
 * The Wheel of Time: Throughout the series, the characters have been trying to prevent the Dark One from breaking free of his prison. In the twelfth book, it's revealed that
 * In the Dragaera series, we learn that the Morganti weapons, which devour the souls of their victims, were created by the Serioli to make war so horrible that no one would ever fight again. It worked... but only for the Serioli, who have a very alien way of thinking. Dragaerans and Easterners don't have the same level of conscience that would restrain them from destroying a soul.
 * Subverted in Jingo, where Vetinari sees the Klatchian empire is remarkably well prepared for a conflict that supposedly flared up only a few days ago, noting: "If you want war, prepare for war." When Leonard corrects him with the page quote, Vetinari thinks about it and says he doesn't see it.
 * The protagonist of The Janson Directive muses upon this concept (with regards to American foreign policy).

Live Action TV

 * In one episode of Star Trek: The Next Generation, a scientist is trying to convince the Federation that warp drive is dangerous, and is damaging space (using similar arguments to how real life greenhouse emissions are damaging Earth). In order to try to convince the Federation to stop using warp drive, she intentionally self-destructs her ship's warp drive in order to cause the very damage she was trying to prevent, just to prove her point.
 * Crichton of Farscape showcases just how destructive wormhole weapons are so everyone would stop trying to bully, blackmail, threaten and Mind Rape the secrets out of his head.
 * In the Star Trek: The Original Series episode "A Taste Of Armageddon", two planets fight a "clean" war by having computers figure out who was killed by each virtual attack, whereupon the designated casualties report for termination. Kirk destroys the computers on one side, forcing them to choose between fighting war in the usual messy manner or making peace.

Video Games

 * Most of the Quest for Glory games require you to play Unwitting Pawn to the villain's scheme before you can put an end to that scheme. In the second game, this is actually in force by your enemy, who needs "A hero from the north" to fulfill a prophecy, and so send the elementals to test you (if you are a true hero you'll stop them). In the third game, you're trying to avert a war between the Leopardmen and the Tribal People, but the only way to discover who's trying to incite the war is to let the war actually happen. In the fourth game, the Big Bad plots to unleash an otherworldly Old God that was partially summoned years ago (and the partial summoning is responsible for the sorry state of the surrounding countryside), and to permanently banish the Old God, the hero has to (unwittingly) finish summoning it.
 * The Maymai Alliance in Spectral Force Genesis wants to stop a war that will ravage the land, but to do it, they'll beat everyone else and then disarm them all.
 * In Assassin's Creed 2, one of Altair's Codex pages lists what he considers the three ironies at the heart of the Assassins - They seek peace, which they try to obtain through murder. They seek to free the minds of men, but require obedience to a leader and a set of rules. They seek to expose the dangers of faith, but use it themselves. He goes on to say that he is trying to find a way to resolve the contradiction but fears that no solution exists.
 * Golden Sun: Restoring Alchemy might destroy the world, and will most likely cause wars. Not restoring Alchemy will destroy the world eventually.
 * Gears of War 2: To stop the Horde from sinking humanity, Marcus and Dom decide to
 * Final Fantasy VIII, of course, features the master plan to prevent : Let her   and jump her ass while she does that.
 * In Final Fantasy X, Maester Seymour believes that the otherwordly entity Sin has trapped the world of Spira in a downwards spiral of death and suffering. How will he save Spira's people from this sorrow?.
 * Pokémon Mystery Dungeon Explorers: Stop time to stop time from stopping.
 * Fight, Mega Man! For everlasting peace!
 * Pokémon Black and White: Team Plasma wants all Pokemon to be released into the wild, and they'll use their Pokemon to force you to give them up.

Webcomics
""Lord Parson doesn't want to lead it. I respect him for that, but I'm also really quite frightened about what will happen to the whole world if he takes command again." One corner of Janis' mouth drooped, and she touched his shoulder. "It will break. I told you. He may war so terribly that it breaks war itself. That is my own hope." She smiled sadly, "And in the long run, I have few others.""
 * Janis from Erfworld is a Hippymancer who wants to see Erfworld at peace. She's become convinced that this won't happen until things get broken even worse than usual.

Real Life

 * World War I was also known as "The War to End All Wars". Obviously that didn't work out quite as hoped...
 * Peter Arnett quoted a United States major as saying, "It became necessary to destroy the town to save it."
 * Practically all any recent war is generally claimed to be needed to ensure peace for the country starting it. Most leaders don't get away anymore by announcing a war for glory or financial gain. One of the well-known protest-signs against the war in Iraq read 'Bombing for peace is like fucking for virginity', and a common rebuttal reads 'How else do you make more virgins?'
 * Back-fires are controlled fires used to stop the progress of an uncontrolled one (by using controlled fires to consume the fuel for the uncontrolled fire), and the origin of the phrase "fight fire with fire."
 * The page quote was used in a more pithy form by Cromwell's English republic as its motto - Pax Quaeritur Bello, or "Peace is sought through war".
 * Said page quote is also a poor example of the trope; the idea is that if your country is militarily weak, you'll be attacked by opportunistic neighbors. So if you want peace, build up a strong enough military that those neighbors will think twice about attacking you. Result: peace, not from starting a war (which would be this trope), but by merely being prepared to fight a war, even though you have no intention of starting one.
 * "It takes two people to make peace, but only one to start a war"
 * Bruce Hoffman suggested in his 1998 book Inside Terrorism that the trend of escalating violence would soon lead to an act of terror so awful that the world's sympathies would turn against the perpetrators. Terrorism would get so horrific that terrorists would abandon it. It hasn't happened yet.

Western Animation

 * In the My Little Pony Friendship Is Magic episode Lesson Zero, Twilight Sparkle literally goes crazy with worry about not turning in her weekly friendship report to Princess Celestia on time and, after failing to find a problem to solve, decides "If I can't find a friendship problem, I'll make a friendship problem!"
 * An episode of Kung Fu Panda Legends of Awesomeness has Po consider releasing a Sealed Evil in a Can so he can defeat it and restore his fan club's faith in him. After a brief Imagine Spot he opts against it, but then accidentally releases it when he drops the jar it was in.
 * The episode "Jet" of Avatar: The Last Airbender features one rather similar to the Vietnam situation in the Real Life section. An Earth Kingdom village has been taken over by the Fire Nation, and the rebels are determined to save it. Their solution? Blow up the dam and kill everyone in the village.

Miscellaneous

 * A certain logic problem revolves around this. You're stranded on an island covered entirely with a forest. A lightning strike starts a fire at one end of the island, and the wind is causing the fire to slowly spread across the rest of the island. How do you survive?
 * Additionally, this is done by firefighters to put out forest fires, with the added caveat that the main fire is so hot it will burn against the wind/downhill/etc.