A Keystone Armynote
is an invasion force or army that's seemingly unstoppable
, except for one particular weakness in the form of a well protected but very fragile component
. It can be an individual soldier, an object or whatever, but if you destroy or tamper with it, the entire army is immediately disabled
. This plot device is handy as it allows a handful of heroes
to win the war without having to depict them fighting off the entire enemy force. Just a daring raid on the enemy's stronghold and BAM! Evil is defeated. It also allows otherwise unstoppable foes to be suddenly stopped dead in their tracks.
General forms include having the MacGuffin
-weakness be the Hive Queen
of an enemy Hive Mind
, the sole source
of all the enemies' powers, or the lone connection
to Another Dimension
. Just like a real keystone, once it's destroyed, the rest falls apart.
Of course, no one ever considered that someone would aim at their army's one weakness
. After all, it would be rather anticlimactic to destroy the Killer Robot
's central control but have a backup one come online in another location.
are likely to be a Keystone Army if they have a Hive Queen
, and as such trashing it is a good way to win the Bug War
. Another common Keystone Army simply replaces the insects with Killer Robots
or Grey Goo
and the Hive Mind with a Master Computer
or evil AI
, and yet another popular variation has an Evil Sorcerer
whose (often Undead
, Mind Controlled
) minions will cease to be a problem due to No Ontological Inertia upon his death/defeat/distraction
. An army of monsters may be defeated by killing the Monster Progenitor
. Easily Thwarted Alien Invasions
often employs such armies. We Cannot Go On Without You
is a case of the player character of a video game being the keystone in their party's army.
Despite the name, only occasionally is the vital component a Cosmic Keystone
. A type of Instant-Win Condition
. See also Decapitated Army
, for when the keystone is the leader. Straight for the Commander
exploits this trope. The armed forces equivalent of a Terminally Dependent Society
. See also Fantastic Fragility
. Compare Untouchable Until Tagged
, when individual Nigh Invulnerable
fighters get mobbed after an unlucky hit.
Similar, but not to be confused with the Keystone Kops
. No relation to Pennsylvania'snote
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Anime and Manga
- In Baka to Test to Shoukanjuu, during the summoner test wars, taking out the class rep is an Instant-Win Condition. 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.
- This could be said of Zero in Code Geass. During the invasion of Tokyo during the Black Rebellion, Zero's vaguely-justified retreat in the middle of the battle proved to be fatal for his troops' morale, and without him there to lead them they quickly fell to Brittanian forces.
- Lampshaded by Diethard earlier in the series, when Zero has gone missing and some of the Black Knights wish to retreat and leave him for dead, rather than risk themselves by sticking around looking for himnote . Diethard points out that Zero is the glue holding the organization together: lose him and they've lost everything.
- Naruto: the army of ninja resurrected by Kabuto was controlled and created by his technique, and thus can be stopped by defeating him. However, just killing him won't get rid of it; he has to actually be forced to stop it.
- The first Naruto Shippuden movie features a nigh-invulnerable terracotta army that is animated by an Eldritch Abomination type being called Mouryu. The only practical way to stop it is by sealing this creature, which is in itself a pretty tall order once its soul and body have reunited. Which, in a surprising moment of Genre Savvy, is why they sealed the soul & body in two different places. Mouryu, unfortunately, has shades of As Long as There Is Evil going on.
- Space Cruiser Yamato 2. Desslok's flagship has a brigade of robots which Kodai (Wildstar) defeats by blowing up their central computer.
- In Tengen Toppa Gurren Lagann, as soon as Simon beats Lordgenome, all of the Beastmen's Gunmen instantly power down.
- In a 1970's Avengers story, 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 arranged the whole thing as a distraction from his real evil plan, and didn't especially care whether the space fleet succeeded or not.
- In the final run of Gail Simone's Wonder Woman run, she faces off against the Citizenry, a genocidal military force so fearsome that they eat 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.
- Judge Dredd: In the Judgment Day arc, the villain Sabbat's zombie army is entirely dependent on his continued control to function, so Dredd eventually assembles a strike team to take out Sabbat in a last-ditch effort to avert the Mega Cities of the Earth from being destroyed completely.
- The square miles of regenerating undead army in With Strings Attached are powered by the Heart of Evil, in a ruined city miles away from where the four and Jim Hunter are surrounded. Having been made a little stupid by rage, and never having grasped just how effective Ringo is at finding stuff, Jeft never imagined that the little band could escape their encirclement, get to the city, go straight to the Heart of Evil, semi-accidentally defeat its powerful guardians, and destroy it, which instantly destroyed all the undead. Which really pissed Jeft off, since not only did he not punish Jim Hunter for his Heel-Face Turn and the four for instigating it, but that heart was expensive.
Films — Animated
Films — Live-Action
- The Avengers. Destroying the mothership causes all the aliens to drop dead. In the DVD Commentary, Joss Whedon admits that he hated having to resort to this trope, but it was necessary to give the heroes a clear victory instead of battling for seventeen more hours of cleanup.
- Played with in Battle: Los Angeles. The alien invaders are ferocious opponents on the ground and are driving back the US military from Los Angeles and other coastal battlefields even before their drone support shows up overhead. The drones themselves are controlled from a large command center that, when taken out, causes the drones to crash and the United States military to regain air superiority over Los Angeles, but the war is far from over and the aliens remain a tenacious force on the ground.
- On two levels in Edge of Tomorrow. Every Mimic force comes with an Alpha. If that dies, the Omega resets everything with foreknowledge of how things went down in the last loop, adapting until the Mimics win. Killing the Omega, however, stops all the Mimics.
- Done in the second Hellboy film, where the demon crown is the keystone.
- In Independence Day, the alien ships are rendered shieldless through a virus uploaded to the mothership, which apparently maintains a constant data link with both the motherships and the fighters. Despite claims that this would only last a few minutes, they never get their shields back.
- The rogue robots in I Robot. Since VIKI was remotely distorting their programming to make them hostile to humans, they immediately became docile upon her defeat.
- In The Name Of The King: A Dungeon Siege Tale has the Krug, formerly mindless beasts who have been magically uplifted by Gallian to serve as his army. Still mostly beasts, they fight using We Have Reserves tactics. As soon as Farmer slits Gallian's throat, the Krug stop and, after standing around in confusion, drop their weapons and wander off.
- Arguably in The Last Starfighter, the Xodan Command Ship's communications turret. It is what allows the entire armada of space fighters to coordinate. Without it, they're not as effective and taken out quickly with a Macross Missile Massacre thanks to the Death Blossom.
- In The Lord of the Rings movies, destroying the One Ring destroys Sauron (this at least is justified, as it's a Soul Jar), which causes his armies to flee while Mordor suffers what can only be called a catastrophic geographical failure.
- The Mummy Returns: The unending army of Anubis turns to dust when the title's Scorpion King is killed and ordered to take his army with him. Justified, because whoever kills the SK, becomes the legitimate master of the army. The good army is just preventing the anubites from getting out into the world, they knew they couldn't win on their own.
- Oblivion (2013) : After the Tet gets blown up, the drones immediately deactivate.
- Pirates of the Caribbean:
- Pirates of the Caribbean: The Curse of the Black Pearl: The curse which rendered the crew of the Black Pearl immortal and unstoppable. Jack and Will break the curse while the crew is in the middle of a climactic battle with Norrington's men, and the second that the pirates realize that their key advantage is lost, they surrender.
- Pirates of the Caribbean: At World's End: The enormous Imperial Armada Beckett brought with him to annihilate the pirates: they all turn tail and run when the Endeavour is sunk, despite it being heavily implied that they vastly outnumber the entire pirate fleet. May simply be a case of Lazy Backup. On the other hand, they were up against the Black Pearl, which was pretty infamous at the time for her actions, as well as the Flying Dutchman, all at once. Especially the Dutchman, who would probably have made it a curbstomp battle given how everyone keeps saying "Control the Dutchman, control the seas."
- The Borg Queen and her Borg in Star Trek: First Contact (at least, those Borg who survived the engine coolant spill)
- And done in "The Best of Both Worlds" when the Enterprise rescues Picard/Locutus, who they use to destroy the Borg Cube...by telling them all to "go to sleep".
- In Star Wars: The Phantom Menace, once Anakin blows up the Trade Federation's control ship, the droid army shuts down.
- Also, the Gungan army turns and flees as soon as their shield generator is destroyed. Justified, because the Trade Federation army had brought tanks to the battle, and with the shield down they could move in. And do.
- This was subverted in cut content of Attack of the Clones; the Jedi blow up the droid control ship, shutting the droids down en-mass, only for them to all power up again seconds later when their new onboard backup systems boot up.
- This is still quasi-true in Revenge of the Sith, given that Anakin is able to shut down the entire droid army after killing the Seperatist leaders. This is largely justified as there was a serious risk of droid rebellion and the controls over those droids were necessary, not to mention that they didn't benefit from leaving their army around if they're already dead.
- The earliest Star Wars example is of course the original, with the Death Star's exhaust port. Reused in Return of the Jedi 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 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.
- In the Total Recall (2012) remake, the Big Bad is making an army of robots to take over the only other habitable area in the world. The protagonist finds out about a shutdown code for the army buried in his memories. When La Résistance leader tries to access the memory, this triggers a hidden code that allows the Big Bad to find him. Also played straight when the protagonist destroys the Fall, a gravity elevator from Europe to Australia, destroying the robots aboard.
- Justified in Animorphs. When the heroes take control of the Yeerk Pool Ship and Visser One, the Yeerk general, it provides the Andalite army with comprehensive intelligence on Yeerk military, that allows them to turn tides in the war and defeat the Yeerk Empire.
- Zig-zagged in The Chronicles of Thomas Covenant, specifically The Power that Preserves. Lord Mhoram thinks that by killing Satansfist, the commander of the army besieging Revelstone, he'll be able to route the entire army. It doesn't work, because the ur-vile loremasters take command immediately upon Satansfists death and restore order. But when Covenant defeats Lord Foul, the ur-viles sense it and decide to call it quits, and the whole army crumbles.
- In Codex Alera without their Queen the Vord are just animals. Dangerous ones, but manageable. Although normally they 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 she blocked this ability in all other Vord since other Queens immediately tried to kill her. Of course, this doesn't guarantee what happens after her death
- The Buggers and their Queen from Ender’s Game. Somewhat subverted in that the Buggers actually know that this is their weakness and actively hide the Queen among the rest of the ships. It takes a genius tactician like Ender to figure out which one is the Queen ship, and even he can't do it in the middle of combat. On top of that, the Queen usually isn't even with her troops, being capable of instantaneous communication from halfway across the galaxy. As a result, Ender ends up having to wipe out whole fleets at a time.
- It's played straight in the narration of the past Bug Wars, with the justification that the Buggers only saw killing a Hive Queen as killing, which was part of the reason for Humanity's fear and hatred of the species; when they happened upon a human colony, they dismantled our technology to see how it worked - after they "dismantled" the colonists to see how they worked. They didn't understand how much that would piss us off any more than they could comprehend that we would kill a sentient queen, rather than the nonsentient workers. They've learned.
- In the Heralds of Valdemar series, the kingdom of Hardorn has waged two wars against Valdemar with forces composed of a few mages and loyal generals and a mass of mind-controlled conscripted troops. In both cases, killing the mage freed the soldiers, who then turned on their generals and ripped them to pieces.
- In Eragon, the Urgal army in Farthen Dur was routed when Eragon took out Durza, thus breaking his mind control over them.
- In J. R. R. Tolkien's The Lord of the Rings, the destruction of the Ring kills Sauron, which confuses and thus incapacitates the parts of his armies which were more directly controlled by his will (e.g. the orcs), which makes them easy game; the not-magically-controlled human armies had various natural reactions, some surrendering and some keeping on fighting.
- On a smaller scale, Sauron's human army from Harad are routed when their chieftain is slain by King Théoden.
- In the post-Apocalypse novel Malevil, depending on a Keystone Army becomes the plan of attack near the end of the novel. The Bigger Bad is marching his army toward the hero's castle, he rules his men with fear and bad luck has cost him his two best lieutenants. If they can kill him and his last second-in-command then his army should disband. They have to succeed because while he can't take the castle in a single battle, they won't be able to win a prolonged guerrilla war against him.
- The Cauldron-Born (an army of undead) from the Prydain Chronicles rampage without end until Taran recovers the Enchanted Sword, Dyrnwyn, and stabs one with it - instantly destroying all of them.
- In the Starfire series, the alien Bugs (big spider monsters with insane numbers on their side) are all but invulnerable... until they are stopped by a tiny flaw in their evolution: kill enough of them at once and the others feel the pain of their deaths. Kind of like a whole race of Obi Wan Kenobis, all feeling a billion voices crying out in pain only to be silenced. Only these guys all have a fatal stroke when they feel them.
- In the Warrior Cats book Firestar's Quest, there's a large horde of Hive Mind rats. Once Firestar kills the leader, they're too confused to fight because they have absolutely no idea what to do now, and those who aren't killed scatter.
- The Trollocs in The Wheel of Time series are the vicious and terrifying foot soldiers of the Shadow. Unfortunately, though they are violent and bloodthirsty, they are also, by nature, selfish and lazy. The only way they can be utilized effectively as a military force is by having Myrdraal control them with a mental link and the use of fear. This makes them a great danger, but if the Myrdraal dies, so do all the Trollocs linked to it. (Downplayed in that each Myrddraal officer is only linked to a platoon or at most a company - you need to kill all the Myrddraal to take out the whole army, and they won't all be in one place.)
- Wind on Fire series: In The Wind Singer, the Zars are known for being unbeatable due to having infinite numbers. The titular Wind Singer's music, however, strips off their magic and makes them age.
Live Action TV
- In the Doctor Who episode "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 Body Horror they've become, the Cybermen kill themselves en masse.
- The Ood from "Planet of the Ood" have a form of hive mind. Destroying it would presumably kill all the Oods. The subversion being that the Big Bad tries to destroy it while the Doctor has to save it.
- The armies of Vortigern in the 1998 Merlin series. Once Merlin disposes of their king, they cease fighting, and Vortigern's rival Uther is shortly thereafter crowned king.
- In the rock opera by The Protomen called "The Father of Death" Dr. Wily, as a Dangerously Genre Savvy Villain, tricks Dr. Light into committing terrorist acts and sacrificing Sniper Joe to destroy his "robot control tower." Turns out Wily has a second control tower located in a fortress and he was only waiting for Dr. Light's attack to give him an excuse to deploy his robot army and declare martial law.
- A BattleTech example would be the initial Clan invasion. When a lucky hit takes out their supreme war leader, the entire hitherto unstoppable Clan advance practically grinds to a halt for months as their Khans return to their distant homeworld cluster to elect a new one. (Choosing a new ilKhan requires a vote by all the Khans, not just the few actually running the invasion at the time.)
- In Chess, the king is all that matters.
- The same goes for the Japanese game of Shogi, which is not unlike Chess.
- This is a classic trope for fantasy RPGs like Dungeons & Dragons. Often times the Always Chaotic Evil races of orcs, goblins and trolls are just as apt to fight each other as they are to attack the humans and other goodly races, until a Big Bad manages to terrify them enough into cooperating under his leadership. The evil races' fear of and/or devotion to the Big Bad is all that keeps them cooperating. If the Big Bad is slain, the evil races will just as willingly turn on each other and the army will disintegrate. Needless to say, PCs are typically the ones who are tasked with destroying the Big Bad before his armies can attack the outmatched forces of good.
- One of the most notable examples in Dungeons & Dragons takes place in the War of the Lance in the Dragonlance setting. Takhisis, the Queen of Darkness and ruler of the evil gods, keeps her five Dragonarmies united through ruthless discipline and their fear of her. When she is banished back to the Abyss by the PCs, the Dragonarmies turn on each other and begin fighting for power. The canon post-War setting includes five territories that are each held by a mutually hostile Dragonarmy, and are just as apt to fight each other as to attack the forces of good.
- This trope actually comes up mechanically in Dungeons and Dragons rather than just from a story point of view. There are several types of monsters who are able to create "spawn" (usually these are undead like vampires and wraiths) and for some of those monsters, those spawn are created completely subservient to their creator. It is possible to build an army of monsters like this, however killing the one who created the spawn in the first place will break the bond of servitude and cause them to act freely. This could be catastrophic for anyone that was using such a monster to create a personal army or just a way to dissipate an army with a single blow.
- Though with the potential to turn into a Nice Job Breaking It, Hero moment as for some of these monsters their creator's control also serves as an effective Power Limiter and/or Restraining Bolt — kill the "master", and suddenly all its former created "slaves" may be finally free to achieve their true horrific potential...
- Iron Kingdoms: for both Warmachine and Hordes, the Warcaster/Warlock is the motive force keeping the walking tanks/giant monsters going, so killing one shuts down/frees their personal troops, and killing all of them (if there's more than one) is the most common automatic win condition.
- Warhammer 40,000 loves this trope.
- The Tyranids in Warhammer 40,000 have certain breeds called "Synapse Creatures" that connect lower-tier organisms into the Hive Mind. 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 entire tendril with multiple Hive Ships defenseless, at least for a while.
- Similarly if the Tau Ethereal is killed, all Tau units have to pass a morale check or flee. Ethereals are the Tau ruling caste and spiritual leaders, and the death of a cadre's overseeing Ethereal will cause the entire cadre to fall back into retreat regardless of how well they were doing before. Subverted in that while Tau initially fight with limited effectiveness, they eventually recover, and their fear and doubt will be replaced with a cold anger over what you just did. Cue Unstoppable Rage... with plasma guns.
- However as of 6th this has been removed, now it just gives the other guy an additional kill point.
- Though not as such in the rules, this is a common way of defeating Ork Waaghs in related material - a Waagh 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 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 Caiaphas Cain 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 him.
- In early versions of Warhammer Fantasy, if the general of an Undead army (normally a Necromancer, Vampire or Tomb King) was killed, the army would quite literally disintegrate. This was toned down in later editions as leader units were nerfed 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, they're likely to run for it.
- 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 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 spin-off game Warmaster has "kill the enemy's general" as one of the generic win conditions for all armies.
- Killing the opponent's king unit in Regicide mode in Age of Empires II gives you instant victory, regardless of how many other units and resources the other player still has. Of course, losing your king will do the same to you. In several campaign scenarios the objective is killing one particular enemy commander or destroying one enemy building too.
- In the single-player mode of the early Battlefield series games, your AI teammates are so incompetent that they will constantly lose ground if you're not being Rambo on the front lines next to them.
- Subverted at the end of Bad Company 2. Destroying the scalar weapon and killing Kirilenko makes Bad Company think that the Russians will no longer invade the US. Cue a bunch of American tanks rolling up beside them to tell them that the Russians have just started to invade through Alaska.
- All the units of the Scrin harvest escort fleet in Command & Conquer 3: Tiberium Wars are powered by Tiberium radiation emanating from a "Relay Node" established at the original Tiberium meteor's crash site, in Italy. While the Node has an operational range that goes as far out as the Moon, its destruction stops every Scrin unit on Earth dead in its tracks, and some even break apart. The Scrin are aware of its importance: it's ludicrously well-defended with everything from stasis shields, Storm Columns and a space fleet to phase fields that render it invulnerable temporarily. Additionally, their original invasion plan called for multiple redundant nodes, but they got sidetracked.
- In single player Diablo, all surviving monsters die when Diablo is killed.
- In Divinity: Dragon Commander, capturing the enemy's capital building and holding it for a turn results in you taking over all of their territory and surviving units.
- In Dragon Age: Origins, killing the Archdemon immediately ends the Blight. Justified since the Archdemon's will is what unites the Always Chaotic Evil Darkspawn hordes into an organized military force. The expansion Awakening subverts this — one of your tasks as the newly appointed Warden Commander in Amaranthine is to investigate why and how Darkspawn are still making fairly organized attacks on the surface (though not on the same scale as a full blown Blight).
- This particular Keystone is also much harder to destroy than most examples. Not only is the Archdemon itself incredibly powerful, it can even transfer its soul to the nearest darkspawn and thus be reborn. So unless a Grey Warden sacrifices himself/herself by taking in the Archdemon's soul (an act that destroys both of their souls) or partakes in Morrigan's Ritual which transfers the Archdemon's soul into Morrigan's developing child, the only way to end a Blight would be to kill every darkspawn in existence. Which is impossible considering they outnumber just about everybody and the Broodmothers can generate more at a ridiculous pace.
- This is why the first Blight lasted something like two hundred years.
- A smaller example occurs in Awakening, where a darkspawn uses a control rod to make a bunch of golems attack you. Killing the darkspawn deactivates all the golems and allows you to loot his control rod, allowing you to use another golem against some darkspawn in the next room.
- In every Dynasty Warriors game except for Empires (which has different battlefield mechanics), defeating a general instantly causes his troops' morale to drop permanently to zero and any officers under his command to flee. So if you can get to the generals and put them down (without getting killed, of course), you can quickly swing the battle with a minimum of fighting. There are a number of tasks (particularly in 3) that are nearly impossible to accomplish any other way.
- The Elder Scrolls V: Skyrim has evil wizards who will often summon up two or more zombies or elemental familiars to fight you. If you kill the wizard, all of their summoned creatures die/vanish. This can comically extend to entire packs of vampires or a dungeon full of necromancers, as they will raise their fallen comrades, who then proceeds to raise more of their comrades. However, if you allow them to do this while keeping track of the last "alive" one, killing him results in the entire room dissipating into dust.
- A standard clause for battles in Exit Fate. Even though you and your opponent has multiple units to fight with, as long as you knock out their primary leader, the rest will flee/surrender and you win. (You get a better rating if you take them all out, though.) However, the same goes for you; if the enemy defeats the unit that represents the main character, it's immediate game over.
- F.E.A.R.'s Replica Soldiers depend on a psychic commander for their orders and become completely inert when the commander dies. Although this is subverted in the expansions (where Paxton Fettel reactivates them from beyond the grave just a couple hours later) and later games (where another psychic commander and then Alma herself take control of them).
- The Federation in FTL: Faster Than Light is guaranteed victory once you destroy the Rebel Flagship, even if the sector, which includes the Federation's Home Base, is completely covered in Rebel-occupied nodes.
- It's mentioned in the backstory of Knights of the Old Republic II that after the massive amount of death and destruction at Malachor V, Revan decided that turning his enemies into allies was a better idea - and, particularly in the construction of HK-47, this trope was his primary idea on how to accomplish that: kill or convert one influential person, watch everything they held together crumble on its own.
- In the Langrisser series, when a commander is killed, all of its surviving soldiers are also removed from the map. It's often to the player's benefit to take out as many of the enemy's soldiers as possible before killing the commanders to get the most experience points.
- Mass Effect - The Rachni have Hive Queens, who reside on toxic planets. The employment of Krogan (a sentient species that evolved on a Death World, so can survive on Rachni Homeworlds and attack the Hive Queens) was the turning point of the war.
- Metal Gear Solid 2: Sons of Liberty subverts this: Arsenal Gear is designed so that it wouldn't be a keystone if it was ever actually used, because while it's almost invincible as long as it has backup, when it doesn't it's so weak the Big Bad is willing to leave it to the Quirky Miniboss Squad as a way of killing them off.
- The Skedar from Perfect Dark. They had been at war with the Maians for a couple of centuries preceding the game's story, and are only stopped for good when the destruction of their home planet and murder of their king crushes their morale.
- One of the bonus missions shows they're Genre Savvy about this to the point that they have three back-up kings ready to take control of their forces in case the one from the main game bites it.
- Quite a few RTS will have this as a condition on various campaign levels. The player's goal is to destroy a single unit or structure, and doing so nets a victory, no matter how many enemy units are left on the field.
- In Sonic Heroes, there are gold enemies that take all nearby 'bots with them when destroyed.
- Justified in a realistic way in the slaughterhouse level of Tom Clancy's Splinter Cell. The bad guys are mercenaries working for cash, and Sam's boss informs him that once he kills their leader/employer, the remaining bad guys will say "screw this" and all go home (since the guy who writes their checks is now dead).
- Although it should be noted that if you're in the line of sight of an enemy soldier when you kill this boss, they do continue to shoot at you, which can quickly turn your mission success screen into a mission failed screen, especially since your controls lock up at this point.
- The show Burn Notice makes the same remark. Michael points out that if you take out the person handing out paychecks, mooks and mercenaries won't stick around to avenge him.
- Something similar happened in The Order of the Stick, when Roy throws Xykon into the portal, he is destroyed. The Goblins in the throne room surrender saying that no one is paying them anymore (though it's more likely that no insanely powerful lich is threatening them anymore). Unfortunately, the goblins tried to surrender to Belkar.
- The Zerg in Starcraft are defeated when their Overmind is killed. The Expansion Pack, 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 Starcraft II, tasks you to destroy a space station with overwhelming forces of zerg crawling on it by taking down its coolant towers.
- The Aparoids in Star Fox Assault. As you would expect from a race of giant alien insects, they keep multiplying as long as their queen is still alive. Luckily, they suffer from apoptosis, so killing the queen also kills them all instantly.
- In Supreme Commander: Forged Alliance, destroying the Quantum Rift of the Seraphim stops their invasion dead in its tracks.
- In both the Supreme Commander game and its expansion, armies will deactivate if their Armored Command Unit is destroyed. In multiplayer mode, losing one's ACU is a condition to lose the game. Justified in that the ACU contains the only person on the field, and that all the other units are robots under his or her control. sACU's are shown to sometimes be piloted by humans, but only in story missions.
- The Commander in Total Annihilation is a good example of this trope. If it dies, you lose and your whole army blows up. The same goes for the oppenent.
- Occurs twice in the Total War games. First, eliminating the general leading an army causes that army's morale and fighting capacity to decrease, making them much easier to defeat (though it's not an instant win). On the strategic map, removing all the adult male members of a faction's royal family (via Assassination, or by bribing / marrying them into your own faction) causes that faction to lose, no matter how many territory or armies it controls.
- Total War also includes an inversion. If a general has a lot of losses, their leadership bonus goes negative. Assassinating a general replaces him with a newly-promoted subordinate who starts at zero. So, killing an enemy's lousy general improves his army's chances for victory.
- Valkyria Chronicles III: Invoked by The Nameless with the operation to assassinate Maximillian. It doesn't work, because said attempt is thwarted by Selvaria.
- Subverted in the Warcraft Universe with the Scourge. The only thing keeping the Scourge from becoming an unstoppable army which would consume everything is the Lich King, who controls the entire Scourge and stops them from doing so.
- The X-Com series loves this trope. In the first game, the entire alien army is run by a giant brain on Mars. In the second game, the leader is hidden underwater. In the third game, you have to seal off the gates to their dimension.
- The third game, Apocalypse, is more of an inversion: In order to seal the gates off, you have to have already destroyed their entire city, and nearly every living thing in it. The gates are the last structure/organism to die.
- Given a nod in XCOM: Enemy Unknown. After you take an alien base, your Number Two believes that you've broken the invasion. The Head Researcher, however, raises an eyebrow at that, mutters under her breath something about "Too easy", then walks off to begin researching the spoils. She's right. Turns out the base was only an outpost of the main force. Played straight, and Justified, at the end of the game however. Taking out the Uber Ethereal kicks off a reaction that causes the alien Temple Ship to implode, taking the majority of their ships, supplies, and leadership with it.
- A popular mechanic in Turn-Based Strategy games such as Fire Emblem, the Final Fantasy Tactics series and the Luminous Arc series: kill the boss of the stage causes all other enemies to flee, stand still or outright melt away, an Instant-Win Condition.
- The highly unique role-playing/real-time strategy hybrid Sacrifice uses this as a foundational rule — for both the player and their opponents. Each level is essentially a glorified arena for two (or more) wizards to compete in, and each wizard is a combination of a mobile base, resource gatherer and spell provider. Death Is a Slap on the Wrist applies because each wizard has a connection to a mystical altar, which rapidly revitalizes them; death merely prevents them from summoning new troops or casting spells, but their army keeps on fighting. Only by defiling the wizard's altar and then slaying them can they be removed from the battlefield — and when that happens, all of their troops drop dead, because they no longer have their master to sustain them. Each battle, then, is a constant struggle by all of the players to take out the rival wizards.
- Played with in the Homeworld series:
- 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;
- In Cataclysm, it's not fully applied: taking down the Beast Mothership and then the Naggarok is a huge blow to the Beast, but all of that means the scattered remains of the Beast aren't near-unstoppable anymore, and there's a post-game clean-up;
- In Homeworld 2 you take down Makaan in the second-to-last mission. As his charisma was the only thing keeping the various Vaygr Crusades together, this breaks their military might in multiple lesser fleets... Including the one equipped with almost indestructible planet killers, that now has nothing stopping them from attacking Hiigara. Destroying those planet killers (using the mighty warship you killed Makaan over) is your last mission.
- The Joining from The Batman 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.
- In the episode "Dark Heart" from Justice League Unlimited, an army of 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 Martian Manhunter frees their power source from the corrupted leader controlling it.
- The Kim Possible movie 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.
- Star Wars' use of this trope was lampooned in one of the Robot Chicken specials, where one of the Imperial commanders scoffs at the idea that "The rebels won!", since they do still have a big-ass fleet. Apparently killing the Emperor and destroying the Death Star is enough for the rest to call it a day.
- Explained in the books by having Palpatine use the Force to unify his armies to fight more efficiently. With his sudden death, the morale blow of the Death Star being destroyed, and the loss of the fleet commander on the super-star destroyer the Imperial Fleet was thrown in disarray. And due to Darth Vader's habit of Force-Choking incompetent underlings, the Death Star had the Empire's best and brightest aboard when it blew up. Plus, you've just seen the other side blow up a ship the size of a moon. The average Imperial officer is going to think "the rebels have a superweapon, Screw This, I'm Out of Here!" not "lucky shot"
- Super Robot Monkey Team Hyper Force Go featured in one episode the Vreen, a Horde of Alien Locusts from the future. Their weakness was the present-day bug they evolved from; when it was found and destroyed, the Vreen disappeared.
- A common problem on Ancient Greek battlefields: when the general died, the whole army tended to rout. This was exploited by the Thebans during the Battle of Tegyra. Outnumbered four to one by their Spartan opponents, they went straight for the officers, whose death threw the Spartan army into terminal paralysis.
- It was also a problem for the Persians, whose overwhelming numbers would mean little if their emperor was killed or routed. Knowing this, Alexander the Great reversed certain defeat, first at Issus and then at Gaugamela, by personally charging through the Immortals and getting Darius III to run, causing the Persians to panic and lose cohesion just when their numerical superiority was overwhelming Alexander's troops.
- Following the events of La Noche Triste, the surviving Spaniards and their Tlaxcaltec allies fled north while being pursued by a far larger Aztec army that cornered them in the plains of Otumba with no possibility of escape. Seeing his enemy weak and outnumbered, the Aztec general Matlatzincatzin followed the Mesoamerican custom, spread his forces and ordered to take as many men alive as possible to sacrifice them back in Tenochtitlan. However, Cortés learned (from the Tlaxcaltecs or from La Malinche, depending of the version) that if he killed the general himself, the Aztecs now deprived of their leader would stop fighting and leave. There was only one chance. Cortés surprised the Aztecs by using his last 23 horses in a cavalry charge that he led himself, something that the natives had never seen before (they were under the impression, in fact, that horses were only used as pack animals), killed the general and captured his standard. As predicted, the Aztecs broke lines and returned to Tenochtitlan. Cortés then took refuge in Tlaxcala, rebuilt his forces and conquered Tenochtitlan the following year, when the city had just been ravaged by a convenient plague of smallpox.