Cavalry Betrayal

Maxwell: Yes, my fellow Christians, we have come to save you...
Wounded civilian: Hooray, it's the Catholic Church!
Maxwell: FROM YOURSELVES!
Wounded civilian: [Beat] Oh no, it's the Catholic Church.

— Hellsing Ultimate Abridged

The heroes have been cornered by the unstoppable hordes of evil, with nothing left to do but hunker down and make the last of their remaining ammo count, when suddenly they hear approaching hoofbeats. They scarcely dare to look - but yes, that is The Cavalry approaching, with the bad guys falling back in their path. A Red Shirt leaps to his feet, waving and shouting for help — and is promptly run through with a sabre.

Basically any instance in which apparent rescuers turn on the heroes — due to either having a secret agenda or mistaking the protagonists for bad guys.

Subtrope of Hope Spot and Friend or Foe?. Compare with: Cavalry Refusal, Changed My Mind, Kid, Betrayal by Inaction, Big Damn Heroes and Always a Bigger Fish. See Also Salvage Pirates, who appears as "help" to the heroes in dire need, but don't intend to rescue them, in fact, they intend to kill them and take their stuff.

As this is a Betrayal Trope, unmarked spoilers abound. Beware.

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Examples:

Anime & Manga

• In Code Geass: Tales of an Alternate Shogunate, this happens to the villains; Suzaku and Euphemia's other forces have realized that Perry is trying to make Japan his own property, and as such, instead of helping him, fight alongside Lelouch and the Black Knights against him.
• Great Teacher Onizuka:
  • In the first episode of the anime. When the three punks who try to blackmail Onizuka are gloating about how much money they're about to get, they accidentally anger a large group of biker thugs who are going to wreck them for their arrogance, when Onizuka shows up and punches his way through the crowd, cowing the bikers who recognise his fearsome reputation. The students are practically crying with relief at being saved by their teacher, only for Onizuka to declare none of the bikers can touch them... because they're his prey.
  • Zig-Zagged later on in Episode 8. After his students at another school have pranked him (by gluing his fingers to bowling balls) and run off, they also find themselves threatened by a gang. Onizuka shows up and at first seems to refuse to help, even going so far as making them bungee jump off a bridge to prove their manliness. However, he then punches all but one of the gang members off the bridge, and Drives Like Crazy after the last one (in the vice principal's Precious, Precious Car).
• Hellsing: Shortly after Millennium attacks London with a battalion of Nazi vampires, an army of some 3,000+ knights in helicopters and gunships are deployed by Section XIII Iscariot. The arrival of this force catches the Millennium forces initially off-guard and relieves the surviving population of London and they are greeted as saviors — until their leader Enrico Maxwell, who has at this point gone far off the deep end, issues the order to kill everyone in London, civilian and vampire alike, resulting in the Iscariot forces indiscriminately mowing down everyone.
• In the 2015 anime adaptation of The Heroic Legend of Arslan, during the disastrous Battle of Atropene, Arslan is in numbed shock after he witnesses firsthand the bloody destruction. He hears Kharlan calling for him and is initially relieved that a familiar person is close, only to realize that the latter and their troops are not here to help him, but to kill him.
• In the first episode of K, our hapless protagonist, Yashiro Isana, is being chased by people who want to kill him-and he has no idea why. He is saved by a total stranger, Kuroh Yatogami who just wants to kill Yashiro himself.
• A rare example of this happening to the antagonists shows up in Mobile Suit Gundam SEED Destiny when Chairman Durandal tries to reinforce his game-ending super-weapon by bringing up the Home-guard. However, the Calvery in this case happened to be lead by veterans of the previous war who'd had enough of Extremists. A few minutes after entering the battle they switch sides, taking a good chunk of the Big Bad's forces with them.
• Ninja Scroll: Despite what he said earlier about the wisdom of remaining neutral, the lord of the Mochizuki clan turns up with his forces to help the protagonists take on the Devils of Kimon. But when Kagerou reports to her lord, he runs her through with his katana, as he's actually the Big Bad.
• In One Piece, during the Arlong arc, after being under Arlong's thumb for eight years and all Marines attempts to save them had been blockaded by the Arlong Pirates, Cocoyashi Village finally had marines reach the island...only for them to be there to confiscate Nami's money, preventing her from buying the village from Arlong.
• Read or Die: It's already been suggested that the British Library has a secret agenda, but the full extent of it isn't clear till they show up in force.
• In Saint Beast, Goh, Shin, Rey and Gai turn against Luca and Judas at the moment they are most needed due to brainwashing, which isn't lifted until it's too late. Then, after Judas and Luca are banished to hell the others plot to free them with the help of the Goddess. The Goddess, however, is plain old sick of fighting and sells them out to Zeus. They get Taken for Granite and have their souls sealed away in darkness. And Judas and Luca are still stuck in hell.

Comic Books

• Crossed: During the onset of the Crossed apocalypse in the United States, a Navy fleet from Pearl Harbor was send with the objective of protecting the cruise ships that would evacuate all the surviving civilians located at San Diego, California. Unfortunately, the fleet somehow fell victim to the infection and instead opened fire at the harbor, destroying the ships and massacring hundreds or possibly thousands of survivors.
• Secret Invasion (2008): Nick Fury and his Secret Warriors teleport into the middle of New York to save the Initiative and Young Avengers from being executed (a little too late to save Geldoff of the Initative). Then, once Yo-Yo's grabbed all the kids, Nick shoots Ms. Marvel, figuring she's a Skrull, and leaves her to be mobbed by the Super-Skrulls. Note that thanks to her origin, Carol is part-Kree, the last person anyone'd suspect of being a Skrull. But, that's Nick Fury for you.
• In Thunderbolts, right after Baron Zemo revealed they were the Masters of Evil, most of the team revolted. They were getting their heads handed to them when the Avengers and the Fantastic Four broke in; one even expressed the view that she never thought she would be grateful to see them. Then Zemo revealed they were mind-controlled.
• Usagi Yojimbo: Happens to Lord Mifume, which leads to his death, and to Lord Noriyuki's father.

Fan Works

• In The Cries of Haruhi Suzumiya, Nagato, in a Knight Templar-ish act to try and improve the situation, does this to Kyon.
• Inverted (and literal) example in Guardians, Wizards, and Kung-Fu Fighters. During the Battle of the Meridian Plains, Viceroy Khenel's cavalry forces arrive and seem to be about to finish off the outnumbered Rebellion, only to instead turn and attack the forces of the other nobles, Khenel having defected to the Rebellion offscreen some time ago.
• In the 'movie-within-a-fanfic' of Movie Night At Freddy's, Foxy is betrayed by his own crew when a thunderstorm threatens their ship.
• One takes place in the appropriately titled cavalry battle of the U.A. Sports Festival in My Hero School Adventure Is All Wrong As Expected. All of Class 1-A agrees to assist each other when possible against the other students and to not attempt to steal each other's points unless doing so is absolutely necessary to advance to the final round while 1-A is in possession of all the points on the field. Todoroki's group betrays the agreement after his mistake allows Monoma to copy his Quirk, despite Hachiman warning the entire class about 1-B's abilities, which puts their chances to make it to the next round at risk. Instead of continuously attempting to retrieve their points from Monoma, Todoroki instead switched targets to Hachiman's party after briefly assisting them because the former knew the latter wouldn't think of them as an enemy until it was too late. It's also heavily implied that Todoroki (and likely Yukinoshita too) didn't want Hachiman in particular to get to the next stage because he's just that dangerous of an opponent.
• The Gurkhas do this to Sasha in the Kim Possible fic Nights in the Big City.
• In the Lyrical Nanoha fanfic Rise of the Phoenixes, :Jane Smythe does this to Miles Fairbrass and Harry Henriksen.
• In the Lilo & Stitch/Star Trek fanfic Starlight, Jumba initially thinks Experiment 628 has come to save them, until he reveals his allegiance to the Borg.
• In The Swarm of War, the Space Marines, twice. First, the ones woken up as a Superweapon Surprise turn out to be largely corrupted by Chaos. Later, during a battle between the King’s Army and the Chaos, forces led by the Loyalist Space Marines attack and wipe out the Chaos… and then the other side; due to the King refusing to recognize the Space Marines as his superiors, his kingdom is branded as heretics.
• In Vainglorious the Jotuns are about to overrun the main evacuation point for refugees when the Light Elves arrive and drive them back. However Arthur has become power hungry and tries to steal the Aether from Taylor so he can conquer Earth and the other Nine Realms for himself. This is a relatively bloodless betrayal up until the Aesir arrive and start duking it out with the Light Elves, with the refugees caught in the crossfire.

Film — Live-Action

• In 20,000 Leagues Under the Sea, after Ned and his group are shanghaied by Nemo, he sets out several messages in bottles with the coordinates of their destination: Nemo's island base of Vulcania. Upon reaching the island and seeing several warships, Ned tries to attract their attention and let them know they're friends, only for the landing parties to shoot at him, seizing Nemo's scientific discoveries their only goal.
• Twice in Braveheart:
  • William Wallace calls on his cavalry to help out the hard pressed infantry at the Battle of Falkirk... but Manipulative Bastard Longshanks had bought them off, thus securing an English victory.
  • Not exactly the "cavalry," but a tense moment (during the same battle!) is averted when Irish conscripts (fighting for the English) switch to the Scottish side at the last possible moment.
• In Dead in Tombstone, Judah Clark arrives at the mine with a posse of armed men wearing badges. However, instead of being their to save Guerrero and Calathea, he is there to collect the gold that the Blackwater Gang owes him.
• In Die Hard 2, the Special Forces unit called in to deal with the hostage situation turns out to be working with the terrorists.
• When Dredd calls for backup at Peach Trees, Ma-Ma calls in support of her own in the form of some bought off Judges.
• Eden Lake: While trying to escape the forest, the injured Jenny meets Adam: the young boy she had encountered the day before. He agrees to show her the way back to town, but instead delivers back into the clutches of the gang.
• On Eraser, Kruger takes part in a rescue mission to save a compromised witness but it turns out his team is dirty. The witness and her protectors are killed and he is framed for it.
• In Fight Club, once the Narrator realizes the full extent of Project Mayhem's plans, he goes straight to the police to tell them everything... only to realize the officers he's talking to are part of Fight Club.
• Headless Horseman: While trying to escape the Town with a Dark Secret of Wormwood Ridge, the teens flag down the sheriff's cruiser. Sheriff Otis invites them in and promises to get them to safety. However, he is part of the conspiracy and goes to deliver them back to town.
• In Hell's Highway, a pair of government agents show up in the nick of time to save Final Girl Sarah from Lucinda. However, to a military installation, where it is explained that there were four equally delusional Lucindias and that they were the result of cloning and accelerated growth experiments. The staff tell Sarah that she is going to become their new test subject.
• Almost occurs in Jarhead when the Marines call in A-10 ground attack aircraft to provide support during a battle, only for the A-10's to mistake them for the enemy and nearly kill them all with the bombing run.
• Judge Dredd. After a shuttle carrying prisoners to Aspen Penal colony crashes, a Capture Team is sent to locate Dredd, a convict on the flight. The Capture Team Leader reports to Chief Justice Griffin.
  Leader: There's no sign of Dredd. He appears to have survived the crash.
  Griffin: You are in error, Capture Team. No one survived the shuttle wreck. Understand? Just find Dredd!
  Leader: The pilot, sir. He's alive.
  Griffin: No one survived the shuttle wreck! Do I make myself clear?
  Leader: Yes, sir. [Shoots the pilot to death]
• On Last of the Mohicans, Colonel Munro finds out General Webb's army is at Fort Edward just two days march from him. Webb flat out refuses to help and advises surrender to the French.
• In The Lone Ranger, the army guy does a Face–Heel Turn after finding out he massacred innocent Indians.
  "These men work for the railroad. So the question is... (points his gun at the Ranger) who the hell are you?"
• In The Lord of the Rings: The Two Towers, it was at first believed that this was the fate of Merry and Pippin when the Uruk-hai who had captured them were attacked by the Rohirrim army; the army leader telling Aragorn and the others they left no survivors. Fortunately, Aragorn found signs on the battlefield that Merry and Pippin managed to escape in the chaos.
• The Monster Club: In the third story, Sam manages to escape from the village of the ghouls with the aid of Luna. Luna is killed, but he manages to make it to the motorway and flag down a passing police car. The police agree to take him to the police station, only to return him to the village: revealing that they are a police escort for the Ghoul Elders returning from London.
• The end of the original Night of the Living Dead (1968) where the black survivor thinks he is rescued only to be shot by the redneck posse that mistakes him for a zombie. It didn't help that he was lurking in the shadows of a dark house and hadn't called to them for help.
• Nothing but Trouble: After escaping from Judge Valkenheiser's grasp, Chris and Diane go back with an entire army of state troopers in tow to arrest the Hanging Judge. It becomes obvious that they're ALL in league with Valkenheiser when they turn their weapons on the pair.
• Happened in Ready to Rumble when Jimmy King got betrayed by his own faction "The King's Men".
• In Red State, three local boys are taken prisoner by the Church to be sacrificed, and the ATF shows up outside to arrest them. When a local sheriff accidentally shoots one of the hostages, the ATF command orders everyone killed.
• Revenge of the Sith:
  • Many of the Jedi deaths following the execution of Order 66 took this form, notably Ki-Adi-Mundi on Mygeeto.
  • The 41st Elite Corps, led by Master Yoda, is sent to Kashyyyk to repel the droid attack on the Wookiees. But then Order 66 is issued and the clones, Gree and Jek, turn against Yoda, though he beheads them before they could lay a shot into him due to the Jedi Master sensing the deaths of his fellow Jedi via the Force. Chewbacca and Tarfful help Yoda escape Kashyyyk, and despite the Separatist forces under General Linwodo taking advantage of Order 66 putting the Republic forces in disarray, the Clones under Faie regrouped and defeated the droids, though most of the Wookiees are captured by the clones and enslaved by the newly-created Galactic Empire.
• Scary Movie: Happens to Drew Decker. After getting stabbed in the breast (and surviving because of the silicone implants), she spots her parents car and runs towards it, screaming for help... Only to get run over because her father was too busy getting a blowjob to notice poor Drew.
• The Jean-Claude Van Damme film Second In Command ends this way. The Moldovan armored division that arrived to relieve the US embassy is working for the Big Bad; they end up getting their asses kicked by the real cavalry in the form of Marine helicopters.
• In Sharpes Battle, the seventh movie in a historical action series starring Sean Bean, this happens to the youngest member of the riflemen, a character who had been around since the first movie. Why couldn't they have used a red shirt?!
• In Sin City, when the Federal Agents arrive at the farm, Lucille naturally assumes that they are there to help and yells at them to not arrest Marv, as he's with her. And then they pour boxes of bullets into poor Lucille, as they are actually a death squad hired by Roark to get rid of him and anyone else knows about Goldie's murder.
• An inversion in Star Trek: Nemesis. The Enterprise is barely holding its own against Shinzon's flagship, when suddenly they detect two more Romulan warships approaching. At first it looks like the situation's going From Bad to Worse, but it turns out that they're from a faction of the armed forces which remains loyal to the legitimate government that Shinzon's coup d'etat wiped out. They get their heads handed to them quite quickly, but the thought was there.
• Suicide Squad (2016): A helicopter arrives to extract Waller and the Squad from Midway City. However, the chopper fails to responds to hails from the Squad and then opens fire on them; having been hijacked by the Joker and his gang.
• Another inversion in Taras Bulba (1962). The Cossack forces arrive in support of the Poles, who are losing in a battle against the Turkish forces. It turns out that the Poles were merely holding back so that they could treacherously attack the Cossacks after they won the battle for them.
• In Timber Falls, Sheryl escapes from the cabin and flees being chased by Deacon. She sees the pickup being driven by Clyde, one the park rangers, and flags him down. However, Clyde turns out to be kin to Ida and Deacon, and knocks her out.
• Happen in the beginning of Tomorrow Never Dies, where the Big Bad has the survivors of the British frigate he sank machine-gunned while they paddled up to his ship hoping for rescue.
• In Violent Night, billionaire Gertrude Lightstone warns the mercenaries holding her and her family hostage that they have an extraction team / kill squad coming to their rescue. Turns out that team has aligned themselves with the mercenaries.
• A variation in Where the Spies Are. David Niven's character foils a KGB assassination only to be chased by the target's bodyguards. However a helicopter flies over and lowers a rope ladder for him. Once inside he congratulates British intelligence for being on the ball when he suddenly realises the helicopter is flown by KGB agents and was meant to help the assassin get away.
• In Wild Wild West, not exactly in combat, but Arliss Loveless promises Bloodbath McGrath and his men assistance in reviving the cause of the Confederacy. As his men wait to meet up with their support, a tank rolls up and opens fire on them. An especially cruel example, as his only reasons seem to be (a) testing out his new weaponry and (b) getting revenge on his former comrades for surrendering at the end of the Civil War.
• In Zulu, the defenders of Rorkes' Drift are at first relieved when a cavalry unit pulls up which had evaded destruction by the Zulu Army. But its commander point-blank refuses to augment the defense, claims there is no hope there, and continues retreating to the west, leaving the lone garrison high and dry. worst: their broken retreat spooks a contingent of already demoralized native troops into deserting and running, leaving the defence worse off than before.

Gamebooks

• Fighting Fantasy stories in a war setting will inevitably feature some of these.
  • Black Vein Prophecy have your La Résistance army facing the forces of your evil brother, Feior, but depending on the units you've recruited, if your army includes some mercenaries of unknown origin, you find out in the last minute that they're secretly serving your brother, and turns on you in the thick of battle.
  • Knights of Doom pulls this off as a Failure Is the Only Option in the climatic battle. Your army, with your ally, Sir Varen, clashes against the forces of chaos of Lord Belgaroth, and moments away from victory, Varen's soldiers suddenly turns on you. Turns out Sir Varen is secretly serving the dread Lord, and you'll be forced to retreat - the book even says if your alliance consist solely of Sir Varen, you'll be overwhelmed and killed on the spot.

Literature

• In Animorphs, this is a common role played by the Andalite military: The final book has the Andalites ready to destroy the human race rather than let it become a resource used by the conquering Yeerk Empire. Earlier books had other Andalites with plans was based on the same well-intentioned extremism: Arbat, who was probably just a rogue faction rather than representing the Andalites in general; and Alloran, who developed a biological weapon to eliminate the alien race of Hork-Bajir.
• Baka and Test: Summon the Beasts gives us the "FFF". On the one hand, they'll help out in summon wars just as much as the next student in the class. On the other hand, if they so much as hear rumors that a girl's been even relatively nice to you, you will suffer their wrath.
• Inverted during the Battle of Thull Mardu in The Belgariad, when King Drosta Lek Thunn of the Nadraks ends up clearing a path for the Western forces, betraying his fellow Angaraks, knowing that siding with the Mallorean forces would only mean subjugation, whereas siding with the West might get his fellow Angaraks' boots off of his neck.
• Lloyd Alexander's The Chronicles of Prydain: In The High King, a powerful ally, who should be the reinforcements the good guys need against the army of the local Evil Overlord, turns out to be a traitor allied with said Overlord. Perhaps a mild subversion in that he pretty much rode into town and announced this a day before the big battle.
• The Crimson Shadow: A rare inversion. During a naval battle between the Avonites and Eriadorans, ships come sailing over from Baraduine (an island ruled by Avon), making the former celebrate. Instead though they attack the Avonite ships, since it turns out that Baraduine would like to be free from their rule.
• The Deluge (Polish Potop) when Prince Radziwil joins the Swedish, the Polish commanders who refused to join the treachery are imprisoned. There is a battle when their units try to break them out. Finally, the literal cavalry (the protagonist's unit) arrives... except he had unwittingly made a pledge on his soul to serve the prince, just in time to get himself stuck on the wrong side.
• The Inciting Incident of The Dinosaur Lords is Jaume being ordered to perform this on Karyl, whose forces are being slaughtered by their common enemy. He charges towards Karyl's forces, making it seems as if he's going to rescue him, only to send the blast of hadrosauruses' sonic attack towards him, crippling Karyl's defence and ultimately leading to man's (first) demise.
• In The Dresden Files book Changes has a double whammy. In the climactic scene, Martin arrives at a standoff between Susan and the Red King... only to take down Susan, revealing himself as The Mole. Except he does this so Susan will be able to kill him and become a vampire, allowing Harry to wipe out the Red Court.
  • Less notable but still important in the same scene was Lea disguising herself as one of Lords of the Outer Night so she could distract the vampires during the double whammy.
• Happens to the bad guys in the second The Heroes of Olympus book. The giant Polybotes is leading an army of monsters against New Rome, and he's pleased to see the Amazons (whom he had earlier tried to bring over to his side) coming to join the battle. Turns out they're here to help the Romans.
• Iron Council in China Miéville's Bas-Lag Cycle, sequel to Perdido Street Station and The Scar.
• Jack Chalker's Lilith: A Snake in the Grass features the sudden arrival of troops supposed to aid the witches in their attack on the protagonist's enemy, only for both defenders and cavalry to turn on the witches, the protagonist realizing he'd been an Unwitting Pawn in a plan to get rid of the witches.
• Inverted in J. R. R. Tolkien's The Lord of the Rings when the Black Fleet of Umbar, allies of Sauron, arrive at the Battle of the Pelennor Fields to the rejoicing of his armies and the despair of the forces of Rohan and Gondor. Only Aragorn had intercepted and captured it, and the ships are full of soldiers from southern Gondor.
• Poor Raphtalia from The Rising of the Shield Hero had to endure this in her backstory. After losing her parents in one of the Waves, she tries to keep everyone's spirits high, and even gets them on the road to rebuilding their town. A force of knights arrive that everyone initially thinks is going to help them. They're not. They're there to slaughter all the remaining adults and sell all the kids as slaves, which leads directly to Raphtalia's hellish ordeal under the sadistic lord she was enslaved to before meeting Naofumi. To say that this experience broke her would be an understatement.
• In Robert E. Howard's "The Scarlet Citadel", inverted for Conan the Barbarian; he arrived on his ally's lands with his forces to find the ally arrayed with his enemies.
• In the backstory of Shadow of the Conqueror, Dayless had an alliance with the nation of Lourane when he was waging his wars, and the two were on course to split Tellos between them. However, Dayless wanted to conquer all the world, and so eventually betrayed Lourane in this manner. This backfired on him, as it led to Lourane forming an alliance with their longtime enemies in order to defeat Dayless and destroy the Dawn Empire.
• Shadow Police: In The Severed Streets, Quill is being pursued by the Ripper. Neil Gaiman arrives to pick him up in a car and spirit him away. However, he is actually there to deliver Quill into an ambush.
• A Song of Ice and Fire pulls one of these, when the "reinforcements" turn out to be invaders.
  • Tywin Lannister "helped" win Robert's Rebellion when his army sacked the capital instead of defending it for House Targaryen.
  • Most infamously at the end of A Game of Thrones when the Goldcloaks turn against Ned Stark.
  • And it happens twice in quick succession in A Clash of Kings, when Ser Rodrik's forces are betrayed by Ramsay Bolton's forces while they are about to launch an attack to retake Winterfell— and then mere pages later when Ramsay the Bastard of Bolton betrays Theon Greyjoy, the man who took Winterfell in the first place, after he opened the gates to his "allies."
  • During the Red Wedding in A Storm of Swords, Roose Bolton and his men storm into the room. Catelyn thinks they're there to help her and Robb: however, Bolton is really in league with the Freys, cuts down his fellow northmen, and stabs Robb in the heart.
  • A backstory example in Fire & Blood; at the final battle of the Dance of Dragons, an army loyal to King Aegon II clashes with a rival force of his late half-sister Rhaenyra's supporters, now battling to put her son on the Iron Throne. Once both armies are locked in battle, Aegon II's commander Borros Baratheon orders his reinforcements to attack...but most of said reinforcements are former Rhaenyra loyalists fighting under duress for Aegon II, and they promptly attacked Lord Baratheon's army from the rear, exterminating Aegon II's last remaining army and leaving his enemies with a clear path to the capital city to depose him.
• In Star Wars Legacy of the Force, series villain Jacen Solo has his fleet surrounded by Confederation vessels in orbit of Kashyyk. He is just beginning to despair when the supposedly allied Hapan armada shows up. Thinking that victory is in his grasp he contacts the Hapan Queen Mother, his lover who is in command of the fleet, to coordinate with her only to have her give him an ultimatum to surrender.
• In A Tale of Two Cities, soldiers arrive during the siege of the Bastille only to turn their guns against its defenders.
• In Graham McNeill's Warhammer 40,000 Horus Heresy novel Fulgrim, the loyalist Marines on Isstvan V do not realize that only three of the Legions going to confront Horus are loyal; their other "allies" turn on them as recounted below.
• A downplayed example in Worm. While fighting Noelle/Echidna things are looking bleak, when the Travelers show up and start hammering her. Sundancer in particular has a power that could decisively and permanently end the threat. At least until Trickster decides he has to grant Noelle's last wish, teleporting the Undersiders and his fellow Travelers into her clutches so she can have her revenge.

Live-Action TV

• The Expanse: At the end of "Nemesis Games", as the UN and MCRN battleships guarding the ring gate are getting their asses handed to them by the Free Navy, another Martian fleet enters the fray, to the relief of the heroes. However, Bobbie recognizes one of the ships and realizes that they belong to Sauveterre, a Martian admiral collaborating with Inaros. Sure enough, the "reinforcements" open fire on the defenders, finishing off the last two ships.
• One of the Video Examples for this page shows an example from Firefly where Malcolm Reynolds is an Independent (Browncoat) trying to call for reinforcements, who pull out at the last moment because the Alliance had just sent in forces so large that they would most likely have annihilated both the ground troops and the cavalry.
• Game of Thrones: During the last days of Robert's Rebellion, Tywin Lannister's forces entered King's Landing as allies, then proceeded to sack the city in Robert's name. Varys and Jaime guessed what was about to happen, but their warnings went unheeded.
• A heroic example comes in the season 3 finale of The Last Kingdom; having promised Aethelwold that he will lead his cavalry in a rear attack against the forces of Wessex when they're locked in battle with the Danes as part of Aethelwold's plan to kill his cousin King Edward to seize power, when the time comes, Lord Sigebriht of Kent chooses to remain loyal and attacks the Danes instead. His actions turns the battles in the favour of Wessex, but Sigebriht is killed in the fighting.
• In Season 4 of Lost, a boat arrives that the castaways believe is going to rescue them, but in fact brings a team of mercenaries with orders to kill Ben and anyone who gets in their way. Some of them do get rescued anyway, but it doesn't help.
  • A similar thing happens at the end of season 1, with several characters getting on a raft and finding a boat which they think will rescue them, but instead it's the Others, who kidnap Walt and torch the raft.
• Happens in Person of Interest season 1 in that episode in which Carter finally takes down Elias.
  • The first time, she tries to evacuate a crime lord who flips on Elias. Carter is shocked when she walks back outside to see her backup has fled. This also happens to one of the Dons when he realizes his muscle has fled but later shoots at them as they leave.
  • When Carter and the Dons hole up in a safehouse, she notices cops surround the building. She recognizes them but realizes they aren't there to help.
• The priceless Star Trek: Voyager episode "Message in a Bottle". The Prometheus is getting trashed by Romulans when some Starfleet ships arrive, only to attack everybody, since as far as they know, it's still under Romulan control. It doesn't help that the EMHs accidentally fire a torpedo at a Defiant-class ship (they were aiming for the Romulans, but missed).

Professional Wrestling

• This happens a lot in wrestling, though how often varies on how swerve-happy a given era, region and promotion is.
• WCW Bash at the Beach '96, which in turn precipitated the biggest Face–Heel Turn in pro wrestling history. After Sting, Randy Savage, and Lex Luger had taken a beating from The Outsiders (Scott Hall and Kevin Nash), Hulk Hogan comes down to the ring, ostensibly to help out Sting and Savage (with Luger having been knocked out), like he's done with others many times in his career... and then leg-drops the fallen Savage, revealing himself to be the Outsiders' mystery partner and heralding the beginning of the New World Order.
• Happened during the (in)famous WCW Invasion angle, while Chris Jericho & Kane were being beaten down at the hands of the nefarious WCW crew, Lance Storm and Mike Awesome. Then, holy shit, Rob Van Dam and Tommy Dreamer show up and join in! Then a bunch of WWF guys ran in for the save: Tazz, Rhyno, Justin Credible, Raven, The Dudley Boys... wait a minute, what do all those guys have in common? Jericho & Kane were promptly pronounced screwed when Paul Heyman left the announce table to proclaim that this invasion had been TAKEN! TO THE! EXTREEEEME! Then later in the same episode, since ECW seemed to have launched a two-front war, there was a match with those ten guys versus five WWF guys and five WCW guys... only to reveal the Alliance of WCW and ECW. Cue fifteen-on-five beatdown.
• Matt Hardy running down to ringside with a chair during his brother Jeff's match with Edge at the 2009 Royal Rumble. This one still managed to surprise because Matt had legitimate gripes with Edge, and even if you did not know that, Edge had sent Matt packing from Monday Night Raw after stealing his girlfriend (well, Kane stole her first, but we digress).
• After BxB Hulk became Open The Freedom Gate Champion, Davey Richards, who lost in the first round of the tournament to decide who would be holding the title, ran out to attack him. The surprise here was that it was Richards' opponent, Yamato, seemingly coming out to stop him, only to join Davey's attack.
• At ROH SoCal Showdown, Colt Cabana ran out to stop Scotty 2 Hotty from performing his finishing move, the Worm, on guest referee Johnny Fairplay, only to give Fairplay the Worm himself.
• At Shine 16, Jessicka Havok, Angelina Love, Amber O'Neal, and Serena Deeb ran out to save new Shine Champion Ivelisse Vélez from Made In Sin, who were none too happy with Velez for retiring Valkyrie leader Radiant Rain. After Havok, Love, and O'Neal dealt with April Hunter, Allysin Kay, and Taylor Made, Deeb hit Velez over the head with the title belt before retreating with Made In Sin and replacing Rain as Valkyrie's leader.
• Joe Bravo and Escobar came out on a February 2015 World Wrestling League show to help Mr. 450 defeat Americas champion Phenomeno BJ. Then they turned on him before Richard Negrín demanded a referee count three on Mr. 450, bringing the Americas Title into the Gentlemen's Club.
• At the 2005 Royal Rumble'', Batista is assured by Triple H that Ric Flair is there to back him up. Ric instead tries to eliminate Batista. Now doubt this was Triple H's order.

Tabletop Games

• Warhammer 40,000:
  • During the Horus Heresy, the Imperium sent seven legions to Isstvan V to crush Horus's insurrection. Three legions formed the first wave and met horrific resistance. When the other four landed, they expected relief and reinforcement; unbeknownst to them, their "reinforcements" were in league with Horus and the three loyalist legions were suddenly caught in a pincer attack between eight traitor legions. Out of hundreds of thousands of loyalist legionaries, only a few thousand escaped the Drop Site Massacre.
  • This also often happens when Inquisitorial forces show up to assist. They only tend to be called when the situation has gotten to the point where the only answers are 1) Kill It with Fire and 2) No Witnesses.
  • The Grey Knights used to have an Apocalypse formation that invoked this trope. They could only deploy if the enemy had at least one greater daemon or warp rift on the table and if, at any point, there were no longer any Chaos models on the table control of the Grey Knights would transfer to the opposing player and the Grey Knights would immediately begin slaughtering their allies to make sure there were no witnesses (why this couldn't wait until after the battle was over is never satisfactorily explained).
  • Due to the cold hard logic they use when devising their battleplans, the Iron Hands Chapter of Adeptus Astartes are more than willing to fire on their allies if they have calculated that this is the most efficient way of defeating the enemy.

Video Games

• An extremely rare villain version happens in Assassin's Creed: Brotherhood, during Sequence 8, where after destroying all of Cesare Borgia's support, he sees one last chance in his Papal Guard army arriving at Roma's gates, only for them to arrest him on orders of the new Pope.
• Happens in Command & Conquer: Tiberium Wars when Killian's reinforcements turn against Nod's Temple Prime. Kane's Wrath reveal that it was actually Alexa who ordered LEGION to pretend to be at the head of Killian's forces.
  Kane: "Of course I could not have planned for an ambush BY MY OWN FORCES!"
• In Dead Rising, if the player follows the path to the best ending, the heroes will call for help. What they get, instead, is a spec ops squad come to ensure the truth behind the zombie outbreak remains a secret, and everyone is fair game, living or undead.
• The U.S.M. Valor in Dead Space. Initially believed to be on a rescue mission, it is later heavily implied that they were full aware of how dire the situation was on the U.S.G. Ishimura and that they would have rather nuked the whole ship than even bother with trying to save anyone.
• The American soldiers and pilots in Desert Strike, who are stranded behind the enemy lines and waiting for the player to rescue them, aren't exactly immune to friendly bullets.
• Towards the end of Dragon Age: Origins: Awakening you have the option of doing this to the City of Amaranthine. The city has been overwhelmed by darkspawn while Vigil's Keep has been ambushed by an even larger darkspawn army. You have the option to burn the city down with Arrows on Fire, killing all the people and darkspawn that your soldiers have trapped inside, freeing you to save your fortress. Fortunately, you can Take a Third Option and save everyone if you have built up the fort enough that it can stand without you.
  • The original game, Dragon Age: Origins, has a "It Was His Sled" moment: when Alistair and the Warden light the beacon at the top of the nearby tower, signalling Loghain's forces to charge, Loghain orders a retreat instead. Cailian and the rest of the Grey Wardens, including Duncan, are overwhelmed. Whether the act constituted a betrayal or not is still debated in- and out-of-universe.
• This happened in the Backstory of one of the towns in Dragon Quest VII. When the monsters first appeared and started terrorizing the town and kidnapping people, one man convinced his neighbors to stand against them. He went ahead to start the fight... and everyone else chickened out. To twist the knife further, this betrayal caused his sister Matilda to hate everyone, allowing the monsters to turn her into a Tragic Monster Barrier Maiden.
• In The Elder Scrolls series' backstory, King Joile of Daggerfall convinced Gaiden Shinji, the legendary Redguard hero and leader of the Order of Diagna, to join him in the Siege of Orsinium (the home city-state/fortress of the Orcs). Joile then convinced Shinji, the Blademaster and founder of the Imperial City Arena, to participate in a Combat by Champion Duel to the Death against the Orc leader, Baloth Bloodtusk. As Shinji and Baloth were fighting, Joile ordered his archers to open fire on both of them. As it turned out, Joile not only wanted to sack Orsinium, but planned to invade Hammerfell after and knew that Shinji would have been a major obstacle. (Joile would get his comeuppance, dying during what would be a failed invasion of Hammerfell.)
• The player character pulls this off in the endgame of Fallout: New Vegas if they're fighting for Mr. House or an Independent Vegas. While you and the Securitrons are fighting alongside the NCR for the majority of the battle, you're also secretly trying to activate the Sealed Army in a Can in order to put yourself in a position to force them out of the Mojave. Once the Legion is routed, you then have to deal with General Oliver, either through force or through diplomacy.
• Subverted in Final Fantasy XIV. when Rhitahtyn sas Arvina is killed by the Warrior of Light, Gaius van Baelsar believes his troops refused to help him (which makes sense as Rhitahtyn is Roegadyn and the Garleans have a massive case of Fantastic Racism) and the soldier tells him he isn't sure at all. However, in actuality, Rhitahtyn had sent his troops away as he didn't want them to die against the Warrior, but some of them came back to aid him.
• Fire Emblem: Genealogy of the Holy War, although the lead-up makes it a bit easier to see it coming. Chapter 5 looks like it's going to be the final battle against all of the antagonists, but rather unexpectedly Velthomer switches sides and starts attacking Freege's army as soon as you get close to Velthomer, double-crossing its allies. All this in spite of the fact that Arvis has now been revealed to be in league with the Loptyr Sect. The chapter ends with Sigurd being led to Belhalla, ostensibly to be cleared of all charges, only to learn that he is still labeled as a traitor and will be killed, along with much of the party (though their fates are mostly left ambiguous).
  • Its interquel Thracia 776 features a sort-of Meta example: late into a grueling defence chapter, an army of green (NPC) Thracian Dracoknights arrive and start heading for the city. The player will probably be exclaiming "I'm saved!" at this point, as the Non Player Characters fly in and clear out the enemies. Until they actually reach the city, upon which they start attacking you. Turns out, they're on neither side: they just want the city back under their control, meaning you're just as much of an obstacle to them as the enemy army. Notable in that it's possibly the only time in the entire series where green NPC units can actually attack you.
  • In the original game and its remake, Marth's father, King Cornelius of Altea, was killed during the invasion led by Medeus, when the army of Gra, who was supposedly allied with Altea, betrayed them and attacked them from the rear.
  • Fire Emblem: Awakening: In Chapter 17 some of your allied forces infiltrate the enemy fort partway through the battle, but Excellus quickly appears and sways them to his side, via holding their families hostage.
  • In Fire Emblem: Three Houses provides an example happening to the enemy. On the Crimson Flower route, during the battle for the Great Bridge of Myrrdin, the enemy commander Judith of House Daphnel receives Leicester Alliance reinforcements led by the noble Acheron, who has been noted for being a Dirty Coward and conveniently spawns near the exit to the map away from the majority of the reinforcements. Should Byleth and the Black Eagle Strike Force strike down the majority of said reinforcements (including their general), he will abandon Judith and leave with his personal guard to save his own hide, which prompts her to order the remaining Alliance soldiers to retreat (and unfortunately for her, it's mission-critical to kill her before she escapes).
• A villainous example happens in the third Galaxy Angel game. Tact defeats Rowil of the Valfask, but takes notice that a fleet of enemy reinforcements suddenly turned around and left him to die, which leaves the heroes unsettled about it. After Wein reveals his true colors, he takes command of those remaining forces.
• In Half-Life, the HECUs sent in to quell the alien invasion of Black Mesa are also there to contain all information of the outbreak by killing every Black Mesa employee they meet, and that includes the Player Character, Gordon Freeman. Some aren't happy about the job, others are. Whatever it is, it gets justified quick when they come to think that Gordon is a psychopath (due to how Gordon by that point has been singlehandedly slaughtering scores of their buddies) and responsible for the whole mess in the compound. They get some karmic justice in the add-on Opposing Force, where the Black Ops soldiers deliver them their own Cavalry Betrayal.
• Inverted in Homeworld: during the final battle a large squadron of Taiidan frigates with two destroyers exits from hyperspace, but they then identify themselves as the Taiidan Rebellion coming to support you.
  • Also played straight in Cataclysm: at one point the Kiith Manaan carrier Caal-Shto shows up with reinforcements, but when the Raiders you're fighting attack them the Caal-Shto is promptly revealed to have been infected by the Beast, and is now an enemy ship.
• The Komato in Iji combine this with Always a Bigger Fish. They're there to kill the Tasen, but you're... well, there.
• After the finale of Left 4 Dead, the characters are rescued by the military in an APC. The subsequent comics show that the army locked them up out of fear that they were carriers and intended to kill them before a horde rush allows them to escape.
• There's a Japanese DOS-era tactical RPG called Legend of the Seven Heroes 2 that ends like this. After a Climax Boss battle against the enemy nation's Big Bad General and his army, an army from the friendly nation shows up, and the main character assumes they're there to rescue them. However, the friendly nation's General arranges a truce with the Big Bad General and decides to kill the main characters, because he figures that the main characters' survival would bring peace between the two nations and thus be politically disadvantageous to both of them. The final battle of the game thus has your 7 characters being attacked from the North of the battlefield by the Big Bad General and his army and from the South of the battlefield by the not-so-friendly nation's General and his army.
• In New Horizons, a cunning captain will act in four steps. Step one: he joins a fleet battle on one side. Step two: he stays at distance and watch, until the fight is over. Step three: He hisses pirate flag and mops the floor with the survivors. Step four: he profits!
• The Player Character themselves can do this in Pathfinder: Kingmaker during the Kellid invasion. Your patron, Lady Jamandi Aldori of Restov, goes to fight them and calls for your army to join her, but you can choose to go chasing after Tristian instead (which is required if you want to complete his Romance Sidequest). Should you do so, you'll finally arrive to discover the opening rounds have already happened and ended in a Pyrrhic Victory for Restov: the Kellids have been stopped for the moment, but Jamandi's army is shattered and her adoptive son Kassil died fighting in her bodyguard, and you're in for a vicious What the Hell, Hero? from Jamandi herself.
• Persona 5 opens up with an inversion. The protagonist acts as the cavalry and rescues a woman from a drunk harasser, only for him to pull out some dirt he has on her and convince her to testify that you randomly beat him up. Not only that, later in the game you net yourself a party member in the form of Akechi, who pretends he's helping you because he worries for Sae. Beat Sae's Palace or not, and he's all too willing to put a bullet through your skull.
• Pokémon Sun and Moon: Wild Pokemon will sometimes call for help if they are losing a battle. Usually this help arrives in the form of another member of their own species, more rarely a Pokemon of another species will show up. And sometimes, their predator will show up, and attack the Pokemon that called for help.
• Sonny begins and ends with these. At the start, the ZPCI come in helicopters, apparently to wipe the zombies currently attacking you, only to turn on you instead as they don't want witnesses. Finally, the last battle of the game is against Galiant the Paladin, whose help you just impersonated and who you just helped in taking down Baron Brixus. Veradux reasons he won't accept the truth and turn on them, so he decides to turn on him first and take you along.
• The Alliance attack on Vaadwaur Prime in Star Trek Online involves your ship attacking defences closer and closer to the planet, calling in one wave of allied forces from different factions each stage. One wave joins the enemy instead. It is the Kazon — Maje Sessen had secretly suborned most of them. This doesn't really work out for them, as the betrayal was predicted and a contingency worked out (some Hirogen are happy to hunt Kazon and Vaadwaur for a while) — and if called in early enough, it even leads to a genuine Cavalry moment (a small group of Kazon show up a stage later to fight beside you, as they found the betrayal dishonorable.).
• Charlie Nash's ending in Street Fighter Alpha 2 has him corner M. Bison, only to be shot and killed by his own men.
• In World of Warcraft, the battle of Angrathar contains a genuine example of The Cavalry when Horde wolf-riders charge into battle to help the beleaguered Alliance. But when the Lich King himself emerges, Putress bombards the entire battleground with Blight, Horde, Alliance, and Scourge alike.
  • In The Frozen Throne mission "Flight from Lordaeron", Arthas and what's left of his army flees from the capitol when the dreadlords revolt against him. He is met by Sylvanas Windrunner but she instead massacres his army and almost kills him, if not for Kel'thuzad and his necromancers arriving in the nick of time.
• The famous Wham Level of Call of Duty: Modern Warfare 2, "Loose Ends", ends with the team holding a cabin against an endless stream of attackers while a huge amount of data is copied on a portable hard drive and most of them are dead when all of the data is secured. The last men make a frantic dash down a hillside without any real cover while under fire from lots of automatic rifles, machine guns, and rocket launchers and just 14 meters from the extraction point the player gets downed. When you regain consciousness a few seconds later, your last teammate Ghost drags you by your jacket and finally helicopters of Shadow Company appear from behind you and mow everything down with their miniguns. And when you finally stumble the last steps to the evac chopper, General Shepherd takes the hard drive and shoots both you and Ghost in the chest. The last thing you see is your bodies being thrown in a ditch, a soldier emptying a gas canister over you, and Shepherd throwing his burning cigar at your face, all the while Price is yelling on comm about how the rest of his team is under attack by Shepherd's men and imploring them not to trust Shepherd.
• In Ys SEVEN, after getting the last crest from the Sea Dragon on Ruin Island you go back to your ship only to be attacked by a giant Titano, Just in the nick of time the Dragon Knights show up and Save you. That is only half true however, They are actually here to rescue Aisha and Arrest you for "kidnapping" her and assassinating the King who was murdered mere moments after Adol leaves said King's bedroom.

Webcomics

• In The Order of the Stick, General Tarquin tells Amun-Zora that he has sent reinforcements to the siege on her city. What he failed to mention was which side they would join.
• Unsounded: The Foi-Hellick Affair was brought to an end when Alderode cast a Hate Plague causing all Aldish people to deeply and violently despise Roger Foi-Hellick, making the rebels and their allies turn on each other as the Aldish violently attacked their recently arrived Crescian allies for protecting Roger as they could see it as nothing but a horrific betrayal.

Web Original

• Inverted in Counter Monkey. During the Thieves' World campaign, the players attacked a cult and the DM expected that they would need help by their employer, Tempus Thales, who came with six guardsman to serve as backup. However, The Cavalry Arrives Late and the party wins the day without assistance. When they heard approaching troops, they assumed it was more cultists and ambushed Tempus as he entered the room, inflicting Facial Horror and driving the campaign Off the Rails in the process.
• In The Gamer's Alliance, a regiment of Proninists disguised as Scun Loyalists manage to fool the Maar Sulais army into letting them get closer during the Second Battle of Victoire. They reveal their true colours by attacking the surprised Maar Sulais defenders who then are forced to flee as they're being outnumbered.
• Parodied in the Anniversary Brawl between the cast of Channel Awesome and The Angry Video Game Nerd when Benzaie shows up, and everyone else who sides with the Nerd over the Critic.
  The Nostalgia Critic: Benzaie! Clench your fist and strike a blow for our side!
  Benzaie: *Punches out an already dazed Linkara*
  The Nostalgia Critic: ...he's on our side.
  Benzaie: *Punches out Nostalgia Critic*
• Much like the source material, the Catholic forces in Hellsing Ultimate Abridged are being mowed down en masse by Dracula's forces. Unlike the source, however, the Papal Knights are nowhere in sight, the forces under Bishop Enrico Maxwell being comprised of fringe factions, the KKK, and the Sacred Order of the Temple Beth Zion. The last of these take the hardware Maxwell gave them and leave, leaving the extremists, the Klansmen and Maxwell to their fates.
• In Worm, Echidna has stalemated Eidolon and her clones are whittling down the combined forces of the Protectorate and the Undersiders. Then the Travelers, the Undersider's allies, show up to help, but Trickster, the leader of the Travelers, betrays everybody to support Echidna, his Protectorate and ex-girlfriend.

Western Animation

• In the three part second season finale of Beast Wars, Cybertron dispatched agent Ravage to prehisotric Earth to aid the Maximals in capturing Megatron. However, Megatron was the only one who knew that, rather than take them back to Cybertron, Ravage was going to terminate all the Maximals and rogue Predacons. Even worse, Megatron used a secret message from his predecessor to convince Ravage to side with him and attack the Maximals.
• Used in a Cliffhanger in He-Man and the Masters of the Universe (2002): Adam, deprived of his sword and stuck facing down a group of villains led by Skeletor, thinks he sees the Masters on the horizon. They turn out to be Skeletor's minions using the Masters' vehicles.
• In ReBoot, this was part of Megabyte's grand strategy during the Web World War: he waited for Mainframe's CPU fleet to take heavy casualties before deploying his own forces, and the moment the invasion ended, he immediately directed his troops to destroy the city's remaining defenses. It was this betrayal that ultimately allowed Megabyte to conquer Mainframe.
• In ThunderCats (2011) during The Siege of Thundera, trusted General Grune shows up toting a Flare Gun that seems to bring the enemy Lizards' Walking Tank fleet to a halt, only for him to perform an Insignia Rip-Off Ritual and an Evil Costume Switch while debuting his nasty new Lightning Gun, while trusted General Panthro...isn't and King Claudus is stabbed In the Back.
• The protagonists of Titan Maximum weren't actually happy to see Troy Hammerschmitt and his Titan Megamum, but that's only mostly because he's The Ace while they are a Ragtag Bunch of Misfits with bad publicity. Everyone else is happy to see him. And then Troy hands his super-advanced robot to the Big Bad, because he was angry that his father considered him an Inadequate Inheritor.
• Total Drama: After getting picked as Bowie's helper in the final challenge, Julia wastes no time wasting time and is an absolute hindrance to him as revenge for eliminating her last episode. She even blackmails him into signing a legally-binding contract that stipulates he'll fork over half of the million to her if he wins in exchange for her cooperation, only to abandon him once he terminates the contract and also takes the saw away for good measure.

Real Life

• Popular theory holds that the Soviet Red Army pulled such an act during the Warsaw Uprising, when Polish resistance fighters sought to rid the capital of the Nazi General Government and military. Research from Polish historians shows this as a complicated and narrow aversion: the Red Army certainly did not actively fight the Polish resistance in the Uprising (as they had, for example, during the onset of the war when they invaded Poland alongside Germany)—they didn't fight anyone at all, and in all likelihood, were badly spent from edging out bloody victories against the largest German army groups of the war during the liberation of Belarus. The Red Army instead decided to stand aside during the battle (despite some propaganda broadcasts from Moscow suggesting Soviet support was imminent). Soviet tank units were denied fuel for advancing even if they wanted to, and only after repeated pressure from the Western allies did the Red Army offer basic assistance to the Polish Home Army [1]. Soviet leadership, Stalin included, chose to focus on other fronts and take Warsaw afterwards—possibly reflecting the very high level of distrust between the parties involved.
• Both Russia and Germany made extensive use of captured tanks. In North Africa, a tactic Rommel returned to was to spearhead his armour with captured British tanks. Even though captured vehicles had been clearly repainted in German insignia (to conform with international law and to safeguard the crews if captured), tired British troops in forward positions recognised the familiar silhouette and sound of what they took to be their own tanks - and relaxed their guard for just long enough. This trick was also used in Russia, although as the tide turned it came back to bite the Germans. The USSR captured so many German tanks that it created special armoured regiments with them - whose job was to spearhead attacks and deceive the Germans into thinking it was their own tanks approaching them. In other fronts, the USSR deliberately painted its tanks in the same disruptive three-colour camouflage used by Germany. Quite often, even this deceived German watchers for long enough, or had them holding fire while trying to ascertain if these were captured Russian tanks being used by German units.
• A naval variant involved the British submarine HMS Morse, which would patrol the approach routes to German submarine bases in France, quite openly on the surface. Tired U-boat crews returning from the Atlantic would see only one of their own - as the Morse was originally a U-boat, captured intact off Iceland. The deception worked, right up until the Morse ran up the White Ensign and fired its torpedos at an unprepared target.
• In an inversion of the above, Hitler also played this role in the areas of Europe the Soviets occupied prior to 1941. Indeed, many guerrilla organizations (such as the Forest Brothers from the Baltic States and the UPA aka Ukranian Insurgent Army) saw him as a potential savior against Soviet Russia, only to find themselves surrounded by German soldiers and Panzers gunning for them (though Hitler did allow some anti-Soviet fighters to join his puppet organizations).
• The Battle of Bosworth Field. The Stanleys, nominally allied with King Richard III, waited until he was separated from his army and charged the King's Bodyguard from the rear, surrounding Richard and killing him in the last time that a British monarch would die in battle.
• The Battle of Sekigahara, the unofficial start of the Tokugawa shogunate that would end the Sengoku Period, was practically Cavalry Betrayal: the battle had five factions' betrayals in it, helped by Tokugawa Ieyasu having courted some of the enemy lords for quite a while beforehand and most of the betrayals were probably spurred simply because Tokugawa's side seemed to have been gaining the advantage. It even saw a few Cavalry Refusals.
• This was how the Bosnian uprising under Husein-beg Gradaščevićes leadership against the Ottoman Empire was squashed in 1850. After routing the imperial army for more than a decade, the final battle that would decide the fate of Bosnia until this day was being fought in what is today the Stup neighborhood in Sarajevo. After defeating the Ottomans, the exhausted Bosnian rebels were overrun by what were supposed to be their reinforcements from Herzegovina-who thought the country would be better off in the crumbling Ottoman Empire.
• Philip VI, King of France, ordered this to be done to his Genovese allies at the Battle of Crecy. The Genovese crossbowmen, ordered by their French paymasters to fight without their pavises (huge shields that protected them from the murderous English longbows as they reloaded), were massacred by the English. When they began to retreat, the French knights charged right over them, either because their commanders were angered by the "cowardice" of the Genovese or were simply too impatient to wait for the exhausted Genovese to withdraw. The French knights paid for their king's arrogance and commanders' bad tactics, however, as they were also crushed by the English forces, faring little better than the crossbowmen had.
• Italy in World War I. Before the war they had an alliance with Germany and Austria-Hungary against France, Britain and Russia, but, between the terms of the agreement being only to fight on defensive ground when the Central Powers declared war first, the long-standing Italian claim to some Austro-Hungarian territories, the German emperor having done everything in his power to deserve the Italian king's hate and actually having better relations with France and Britain than with their own allies, first refused to enter the war, and when they did it was on the other side.
• The Battle of Ankara between the Ottomans and Timurids was a crushing defeat for the former, since a substantial force of Black Tatars on their side deserted them when they saw the odds where on their side and joined the stronger side. This battle resulted in the first and only time an Ottoman sultan was taken captive and it was followed by a succession crisis when his sons fought each other in a civil war for the throne.
• The Ottomans were subjected to this again in the Siege of Vienna when their Wallachian vassals not only retreated when the Polish hussars charged, but it was revealed that their prince Șerban Cantacuzino was secretly in league with the Christians, having warned them about the Turks' plans, movements and tactics in exchange for the throne of Constantinople. Though the Habsburgs promised to give him Constantinople for his assistance, he died suddenly before he could claim his reward - presumably poisoned by his fellow Wallachians due to his highly unrealistic expectations.

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