History Main / KeyStoneArmy

** The Tyranids in ''TabletopGame/Warhammer40000'' have certain breeds called "Synapse Creatures" that connect lower-tier organisms into the HiveMind. Killing a local Synapse Creature causes the portion of the Hive under its sway to become disoriented until another one can move in to take its place.
** Even more so with Norn Queens. Apparently, poisoning one can make an entire tendril with multiple Hive Ships defenseless, at least for a while.
** Similarly the Tau ideology of the Greater Good places a tremendous amount of respect and symbolic value on the members of the Ethereal caste, their ruling caste and spiritual leaders. The death of a hunter cadre's overseeing Ethereal will cause the entire cadre to [[HeroicBSOD fall back into retreat regardless of how well they were doing before]]. In game terms, if the Ethereal is killed, all Tau units have to pass a morale check or flee. {{Subverted}} in that while Tau initially fight with limited effectiveness, they eventually recover, and their fear and doubt will be replaced with a [[TranquilFury cold anger]] over [[MoralEventHorizon what you just did]]. Cue UnstoppableRage... [[BeamSpam with plasma guns]]. However as of 6th this has been removed, now it just gives the other guy an additional kill point. This was [[ObviousRulePatch likely due]] to the surprisingly common strategy of shooting your own Ethereal.
** Though not as such in the rules, this is a common way of defeating Ork Waaaghs in related material -- a Waaagh is the result of a powerful Ork Warboss gathering together a number of warbands and going to war; killing the Warboss means that, without his charisma and domineering personality lashing them together, the assembled Orks will return to their normal habits of shooting at each other as well as the non-Orks. Best demonstrated in the ''Literature/CiaphasCain'' novel ''Death or Glory''; when Cain kills the Warboss, one of the Orks watching the fight tries to order the rest to attack, only for another to say something along the lines of "'oo says ''you're'' da new boss?!?" and attack one another.
** While this is also a common tactic against Chaos forces (whose commanders have to deal with ambitious subordinates, OverzealousUnderlings, personal rivalries, and religious schisms on a regular basis), it doesn't always work (especially if the commander was just a figurehead for TheManBehindTheMan). Another Literature/CiaphasCain story has a Warp-tainted warlord with a permanently CompellingVoice be killed by Cain, causing his army to attack (and his pilot to starve to death waiting for his return).

** In Alpha Legion Chaos Space Marines specifically mitigate this trope by having no centralized leadership. In the tabletop, this translates to the opponent being forced to kill every character in the army before they can earn a victory point for assassinating the leaders. In the lore, thanks to a BackupTwin and an IAmSpartacus culture, nobody's entirely sure if their original leader is dead or not or weather the many warbands follow any overall structure anymore.

* In early versions of ''TabletopGame/{{Warhammer}} Fantasy'', if the general of an Undead army (normally a Necromancer, Vampire or [[{{Mummy}} Tomb King]]) was killed, the army would quite literally disintegrate. This was toned down in later editions as leader units were {{nerf}}ed and killing them became a less daunting prospect, but it's still bad news.
** Dogs of War (essentially a lot of mercenary companies scraped together into an army) don't much care about their general... but if the Paymaster is killed and his treasure chest captured, [[OnlyInItForTheMoney they're likely to run for it.]]
** Inverted by Thorgrim Grudgebearer, who has the ability to grant his entire army Hatred (re-roll misses in the first turn of melee) when he dies.
** While only mentioned in the fluff, it is generally considered common Warhammer knowledge that killing a major Warboss will inevitably cause any WAAAGH to eventually collapse in on itself, as weaker Warbosses and Orcs start to [[EvilPowerVacuum turn on each other to claim the title]]. However, this has no representation in the rules -- no petty infighting is going to make them stop in the middle of a fight they're already engaged in.

** The earliest ''Franchise/StarWars'' example is of course [[Film/ANewHope the original]], with the Death Star's [[AchillesHeel exhaust port]]. Reused in ''Film/ReturnOfTheJedi'' with the Death Star II's main reactor, not to mention Palpatine dying with it. These both are arguably subversions, however, given that the Empire, in the original ExpandedUniverse, kicked the rebels off the moon shortly after the Battle of Yavin and that the civil war still officially went on for another fifteen years after Endor and ended in a draw. In the new EU, on the other hand, the trope is present but [[DownplayedTrope downplayed.]] The rebels kicked the Empire off the moon instead and the war still carried on, but only for about a year. The loss of centralized leadership and the massive financial losses the Empire suffered, not to mention a vast increase in support for the rebellion, all did the Empire in as it succumbed to infighting. So while the act of destroying the second Death Star and killing the Emperor did not magically make the Empire vanish, it did pretty much decide the course of the war in the Rebellion's favor. It helped that the Emperor had set the system up this way deliberately as an attempt at VetinariJobSecurity, and left orders in the wake of his death to devastate loyalist worlds out of sheer spite.

* In ''Literature/BakaAndTestSummonTheBeasts'', during the summoner test wars, taking out the class rep is an InstantWinCondition. Naturally the students usually try to protect their leader, but sometimes the opposing class will bait them somehow and lure them away so as to weaken the rep's defenses and take them out.

* In ''Literature/CodexAlera'' without their Queen the Vord are just animals. Dangerous ones, but manageable. Although normally queens possess the ability to give birth to new subsidiary queens, so killing one may rout the Vord in the area, but won't destroy their threat. The Vord Queen in Alera explicitly says [[spoiler:she blocked this ability in all other Vord since other Queens immediately tried to kill her]], leaving one primary keystone target.
** Ultimately, though, this trope is averted: after [[spoiler: The original Queen dies]], the Vord revert to their simple, individualistic natures, but because they're arranged in a massively tight formation charging into the Aleran defenses, they still have no choice but to keep attacking. Although the battle is made easier since the Vord near the back will desert and some others might resort to attacking each other, the Aleran forces still have to fight on for several hours after their victory is assured.

* In Creator/JRRTolkien's ''Literature/TheLordOfTheRings'', the destruction of the Ring [[DecapitatedArmy kills Sauron]], which confuses and thus incapacitates the parts of his armies which were more directly controlled by his will (e.g. the orc leadership), which makes them easy game; the not-magically-controlled human armies had various natural reactions, some surrendering and some keeping on fighting. While it is shown that Orc kingdoms and tribes can still exist without Sauron's direct control, he was the only thing unifying them into a superpower, and without said leadership they splinter and become easy pickings (even the relatively large Orc/Goblin realm in ''The Hobbit'' ultimately had the bulk of its strength exterminated by fewer than 2,000 Elves, Men, Dwarves, and Eagles).
** On a smaller scale, Sauron's human army from Harad are routed when their chieftain is slain by King Théoden.

*** The Trade Federation's droid army has one as an ''intended feature'': as part of their safety measures, their army was designed to remain active only if receiving an active control signal broadcast by a dedicated ship. This however backfired on them when Anakin managed to blow up the only one they had left in Naboo's orbit, as the droids shut down on the spot upon losing the signal.

* The Zerg in ''VideoGame/{{Starcraft}}'' are defeated when their [[HiveMind Overmind]] is killed. The ExpansionPack, ''Brood War'', subverts this; without the Overmind to direct their actions, the Swarm launches into a mindless frenzy and slaughters half the Protoss population. ''Then'' lots of backstabbing intrigue about control of the Swarm happens. A similar effect occurs when a Cerebrate is killed, except the Cerebrates only control specific broods, or sections of the swarm. Both example however apply only to the story and lore, and not the actual gameplay, except for specific campaign scenarios.
** The campaigns themselves are rife with examples where the key to victory against overwhelming odds lies in destroying weak points; for example, "Shatter the Sky", one of the two alternate penultimate missions in ''VideoGame/StarcraftII'', tasks you to destroy a space station with overwhelming forces of zerg crawling on it by taking down its coolant towers.

[[folder:Web Comics]]

* The Joining from ''WesternAnimation/TheBatman'' are an army of robots. They are defeated twice by this: the first time by a self destruct code that had been built into the various parts they were made off. The second time they were defeated by a signal to their mothership ordering them to go offline.
* ''WesternAnimation/JusticeLeagueUnlimited'':
** In the episode "Dark Heart", an army of [[NanoMachines self-replicating robots]] is defeated when the heroes destroy the titular dark heart commanding them.
** From the same series, an alien army is defeated when the ComicBook/MartianManhunter frees their power source from the corrupted leader controlling it.
* The ''WesternAnimation/KimPossible'' [[TheMovie movie]] [[WesternAnimation/KimPossibleMovieSoTheDrama So The Drama]] has this. Dr. Drakken distributes toy robots around the world which turn out to be giant killer robots that he can activate with a command signal he broadcasts from his headquarters. When he launches the worldwide attack, Kim and Ron foil it by knocking out the main broadcasting tower, causing all the robots to revert back to their harmless toy forms.

* Berlin was this for Nazi Germany in 1945, though the country could hardly be considered an unstoppable Force at that point. By the time of the Siege of Berlin, Germany still had a sizeable force fighting bitterly across Europe. However, the Red Army had managed to encircle Berlin and cut the city off from the rest of the German army. Attempts from the Germans to break through the Soviet encirclement failed, and they could do nothing but watch as Berlin fell. With the fall of their capital and the loss of much of their leadership, the Nazi forces still fighting in Europe surrendered. The Germans might have fought on much longer had their capital not fallen to the Soviets.[[note]]However, one reason why the Germans fought so stubbornly to the end was the loyal oath that had been imposed on the Armed Forces in 1938 - not to the nation, but to Adolf Hitler himself. As long as Hitler lived, an oath to serve him unto death had a religious force. This explains why so may German officers stayed loyal in August 1944 after the assassination attempt - they regarded breaking the oath, even to Hitler, as unthinkable, even contemptible. But when Hitler died, however, it suddenly became completely permissible to surrender. This explains why the Wehrmacht collapsed so quickly after April 30th - had Hitler lived, the war would certainly have been prolonged and the Alpine Redoubt would have become a reality.[[/note]]

* Berlin was this for Nazi Germany in 1945, though the country could hardly be considered an unstoppable Force at that point. By the time of the Siege of Berlin, Germany still had a sizeable force fighting bitterly across Europe. However, the Red Army had managed to encircle Berlin and cut the city off from the rest of the German army. Attempts from the Germans to break through the Soviet encirclement failed, and they could do nothing but watch as Berlin fell. With the fall of their capital and the loss of much of their leadership, the Nazi forces still fighting in Europe surrendered. The Germans might have fought on much longer had their capital not fallen to the Soviets.

* Invoked and discussed in ''Manga/SoulHunter'': When Taikoubou is tasked with the Houshin Plan and has to defeat Dakki and her followers, he points out that actually slaying all the followers listed in the Houshin List is unnecessary, and by taking down Dakki her army would disband. For the first part of the manga, his plans revolve around finding a way to get rid of Dakki herself, but unfortunately she's out of his league not only in power but also in strategy.

* At one point in ''VideoGame/DevilMayCry3DantesAwakening'', Dante has to fight [[HumanChess a demonic chessboard]]. If the King is destroyed, the rest of the board self-destructs. This isn't as easy as just saying it, however - not only do the other pieces continually attack, but both of the Rooks must be killed first or the King will simply switch places with one every time Dante tries to hit him.

** In the first game, the mighty Taiidan Empire is defeated, and you can claim your ancestral homeworld of Hiigara, the moment you take down the Imperial flagship and the empire on it. {{Justified}} because the Taiidan had pissed off enough people that the Galactic Council, and the Bentusi in particular, take the chance to ''enforce'' your claim to Hiigara, while the Taiidan rebellion takes the chance to destroy the databank with the emperor's genetic code, thus preventing a clean succession (the emperor was mad and had killed off all the possible heirs, and cloning him would have been the only way to find a successor acceptable to the whole military. It's implied he himself is a clone of the previous emperor) and creating their Taiidan Republic while the Imperialist forces (at least those who haven't defected) fight each other to try and impose their respective leaders as the new emperor. Though this is ''far'' from the end of the conflict; the former Empire [[BalkanizeMe is now a fractious mix of bickering successor states]], and a lot of serious military hardware is in the hands of [[TheRemnant various "Imperial Loyalist" groups]] and FormerRegimePersonnel who've turned warlord or pirate.

* In some Adventure Mode levels of ''VideoGame/HyruleWarriors'', the enemy will send out an elite force of morale-boosted mooks led by an officer with a stat buff. These forces can endanger your keeps more quickly and are tougher to deal with than the ordinary Raid Forces but will rout instantly with the defeat of their officer.

** ''Anime/DoraemonNobitaAndTheCastleOfTheUnderseaDevil'' has the [[AIIsACrapshoot Mad AI]] Poseidon, leader of theunderwater robot army who wiped out the inhabitants of Atlantis and is targeting the surface world. Once Poseidon is destroyed via Buggy's EatMe HeroicSacrifice, his robots and drones quickly come to a standstill.

* ''Film/InTheNameOfTheKing'' has the Krug, formerly mindless beasts who have been magically uplifted by [[EvilSorcerer Gallian]] to serve as his army. Still mostly beasts, they fight using WeHaveReserves tactics. As soon as Farmer slits Gallian's throat, the Krug stop and, after standing around in confusion, drop their weapons and wander off.

* ''Franchise/TheAvengers'':
** ''Film/TheAvengers2012'': Destroying the mothership causes all the aliens to drop dead. In the DVDCommentary, Creator/JossWhedon admits that he hated having to resort to this trope, [[EnforcedTrope but it was necessary]] to give the heroes a clear victory instead of battling for seventeen more hours of cleanup.
** A DeletedScene in ''Film/AvengersEndgame'' [[LampshadeHanging lampshades]] this when Rocket Raccoon asks the original six Avengers why they didn't just blow up the mothership immediately and laughs when he learns they didn't know that this was the army's weakness at the time, as this is a well-known fact in his galaxy.

* In ''Film/HeneralLuna'' as it was in history, the Philippine Army was barely able to hold on when fighting the encroaching Americans, being poorly-trained and suffering from a lack of resources. Thanks to the titular General Antonio Luna and his military genius, they were able to keep the fight up. After his death at the hands of his own countrymen, the situation becomes so bad that the Filipinos are routed in many battles unable to even kill any of their enemies in return.

* ''Film/InTheNameOfTheKing: A VideoGame/DungeonSiege Tale'' has the Krug, formerly mindless beasts who have been magically uplifted by [[EvilSorcerer Gallian]] to serve as his army. Still mostly beasts, they fight using WeHaveReserves tactics. As soon as Farmer slits Gallian's throat, the Krug stop and, after standing around in confusion, drop their weapons and wander off.

* In ''Film/TheLordOfTheRingsTheReturnOfTheKing'' movies, destroying the One Ring destroys Sauron (this at least is justified, as it's a SoulJar), which causes his armies to flee while Mordor suffers what can only be called a [[LoadBearingBoss catastrophic geographical failure]]. This was added in the movie, as the result from the books (several hours of orcs fleeing, surrendering, killing themselves, or performing hopeless stands) doesn't show well in cinema.

-->'''Rick:''' ''(as he stabs the Scorpion King)'' Go to hell! And take your friends with you!
* ''Film/{{Oblivion 2013}}'' : After [[spoiler:the Tet]] gets blown up, the drones immediately deactivate.
* ''Franchise/PiratesOfTheCaribbean:''

* ''Film/TotalRecall2012'' remake:

* Zig-zagged in ''Film/WonderWoman.'' Diana entirely believes that mankind's love of violence and warfare is being caused by Ares and knows that once she kills him, humanity will end the war and return to peace. [[spoiler: When she kills the man she thinks is Ares though, the trope is horribly, painfully averted. She sees that men will continue fighting, and is forced to realize that the WarIsHell landscape she spent half the movie making her way across is really nothing to do with influence. After briefly flirting with the possibility that HumansAreBastards who don't deserve her help, she goes on to confront the actual Ares.... Who casually reveals that he influences humanity to fight each other, he doesn't force it. When Diana kills Ares, she sees several soldiers removing their helmets and looking confused and relieved, but it could just as easily be because two Gods were fighting in their base and they're happy to be alive.]]

* ComicBook/{{Thanos}}:
** In a 1970s Comicbook/{{Avengers}}, ComicBook/{{Thanos}}'s space fleet is attacking Earth. It turns out that all of the multivaried aliens in the fleet are depending on a single gizmo on one ship to translate for them so they can understand each other. The Avengers destroy it, and then win fairly easily. Somewhat justified when it turns out that Thanos [[XanatosGambit arranged the whole thing]] as a distraction from his ''real'' evil plan, and didn't especially care whether the space fleet succeeded or not.
** Even Thanos' actual evil plan, using the Cosmic Cube to make himself a god, turned out to be this. Captain Mar-Vell (alongside a small group of allies made up of Drax the Destroyer, Drax's daughter Moondragon, Thanos' brother and father, as well as Iron Man) is hopelessly outmatched by the all-powerful Mad Titan, especially after he uses the Cube to become one with the cosmos. However, Mar-Vell realised that despite becoming a RealityWarper, his power was still in-flux and reliant on the Cube. Thanos tried to age him into dust, but with his dying breath Mar-Vell managed to strike the Cube and [[ResetButton undo Thanos' changes]]. As a side-effect, Thanos was turned to stone, dead. The members of his forces that remained on his flagship and ''weren't'' members of the distraction fleet then scattered and fled without him to lead them.
* In the final arc of Creator/GailSimone's ''Franchise/WonderWoman'' [[ComicBook/WonderWoman2006 Vol 3]] run, she faces off against the Citizenry, a genocidal military force so fearsome that they eat [[Franchise/GreenLantern Green Lanterns]] for breakfast. Fortunately, their self-justification is based on their own strength, so when Wonder Woman defeats their leader said leader loses all status and Diana's able to order them to stand down.

** ''Film/{{The Avengers|2012}}''. Destroying the mothership causes all the aliens to drop dead. In the DVDCommentary, Creator/JossWhedon admits that he hated having to resort to this trope, [[EnforcedTrope but it was necessary]] to give the heroes a clear victory instead of battling for seventeen more hours of cleanup.

** In the episode "[[https://tvtropes.org/pmwiki/pmwiki.php/Recap/DoctorWhoNSS2E13Doomsday Doomsday]]", when the space-time rift that pulled through an army of Cybermen and a ship full of Daleks is closed, it starts to suck them back in.
** In "The Age of Steel", the Cybermen are stopped when the program preventing them from feeling emotions is disabled - upon realizing the nature of the BodyHorror they've become, the Cybermen ''kill themselves en masse''.
** The Ood from "[[Recap/DoctorWhoNSS4E3PlanetOfTheOod Planet of the Ood]]" have a form of hive mind. Destroying it would presumably kill all the Oods. The subversion being that the BigBad tries to destroy it while the Doctor has to save it.

* The armies of Vortigern in the 1998 ''[[Series/{{Merlin1998}} Merlin]]'' series. [[spoiler:Once Merlin disposes of their king, they cease fighting, and Vortigern's rival Uther is shortly thereafter crowned king.]]

* ''Series/StarTrekTheNextGeneration'': The [[PuppeteerParasite "bluegill" aliens]] taking over Starfleet are defeated when the mother parasite is killed. Her death cause all other parasites to vanish causing all taken over personnel to be freed.