Sometimes, in combat, it's hard to tell who your friends are.
In a combat zone, firing on, questioning, or fleeing your friends is common. With Due Respect may not be very respectful, as the junior cannot tell whether the character speaking to him actually is his senior officer.
Confusion deliberately induced by the villain is Let's You and Him Fight. Dressing as the Enemy can also lead to this, as can catching someone unawares (this sort of confusion can also be induced via Disguised Hostage Gambit). Unfriendly Fire often relies on this to cover up the murder. Extreme forms of Divided We Fall can lead to this. The Berserker often does not care which he's attacking, or is too caught up in the rage of battle to tell them apart. Can apply even if one character does know who is there, but has been lied to about his character, which often leads to the problems of Would Not Shoot a Good Guy.
This is often even worse before or after the actual fighting, while you are sneaking about territory that you know that the enemy is about somewhere, or into his stronghold, especially if you are a prisoner or trying to contact one. (See Alone-with-Prisoner Ploy.)
Note that the characters do not have to be in doubt — they can just be wrong. They may (briefly) believe the approaching forces to be friendly, or they may go through all sorts of fighting and fleeing believing them to be foes. Get It Over With often reveals this trope was in play.
Truth in Television. In Real Life, 'friendly fire' (AKA "blue-on-blue engagement" among NATO forces, fratricide, or "own goal" as the Brits call it) has been a serious issue in many conflicts. This problem goes far enough back that it's responsible for battle cries, military uniforms, battle standards, and heraldry. Books have been written about the resulting investigations. Armies have developed many innovative designs to avoid it, but have never been 100% successful — partly because if you can always identify your friends, so can your enemies.
Not to be confused with the game show hosted by Kennedy.
Contrast with Friendly Fireproof, where you can hammer away at your teammates and not cause any damage at all.
- In the Back Story of Mobile Suit Gundam 00, Sumeragi and Mannequin mistook each other's forces for the enemy and effectively obliterated their allies before realizing it. Sumeragi's love interest died in that battle, too.
- In Mobile Suit Gundam Wing, the five Gundam pilots start out wary of each other and sometimes end up fighting among themselves after destroying their mutual enemy. None of them were told by their handlers that there would be others like them, so the HeelFace Turn they all had concerning the objective of their mission prior to launch made them into each other's potential enemies. Unlike what the fandom would have you believe, they don't come together as a five-man team until near the end of the series, but they do often work in pairs of varying combinations once the misunderstandings are cleared up.
- In Code Geass, Lelouch uses the enemy's Identification: Friend or Foe (IFF) signals to track their movements.
- In the Ruby/Sapphire arc of Pokémon Adventures, Intrepid Reporters Gabby and Ty are horrified when they realize their boss is Archie and has thus prevented any news of Team Aqua's crimes to go broadcast. What's more, they witness him and Maxie teaming up and deciding to go to the Cave of Origins together in a stolen submarine. Gabby immediately wants to announce the truth to the rest of the news station, but Ty points out that if their boss was the leader of Team Aqua, it may already be filled with undercover grunts and the two of them wouldn't know who they could trust. Thankfully, in a slight aversion, the two decide to ditch the news station entirely to inform the people they know they can trust: the Gym Leaders.
- In the Mobile Suit Gundam sidestories known as MSV, there is a Mobile Suit called the GM Camouf, which was a Zeon MS designed to look like a GM to fool the Federation. However, it proved to be a disaster when a group of Camoufs were destroyed by their own Musai transports!
- The modded "Zeta Zaku" by Iino in Mobile Suit Gundam ZZ has a Zaku II's head in the place of the Zeta's (the Zeta's head was damaged and the Zaku was the only thing they had on hand for repairs). Comically, it's Judau who's confused and starts firing at it in his shock.
- In episode 12 of Martian Successor Nadesico, the Nadesico fires on both Jovian and UEAF ships during one battle. At first it confuses everyone as to why the ship did that, but it turns out that the Nadesico has a learning computer, and still retains information that the UEAF is considered hostile (due to their actions in preventing the ship from going to Mars in earlier episodes). The UEAF attempts to reprogram it, but Ruri disagrees, since formatting the computer would cause it to lose valuable combat data it acquired when they went to Mars. So she decides to reprogram it herself with the help of Akito and Seiya to allow the Nadesico to retain its information, while simultaneously erasing the UEAF forces as hostile.
- In Tintin: The Red Sea Sharks Tintin and his friends make an escape riding camels. Mull Pasha (Tintin's old foe Dr. Müller), head of Bab El-Ehr's forces, phones his air force commander to send a squadron of Mosquitos after them, adding "armoured cars are already on their way". Due to a misunderstanding, the Mosquitos fire on and destroy the armoured cars pursuing Tintin and co.!
- In The Avengers, after Hercules had been rendered comatose, Zeus brought the Avengers to Olympus and attacked them. A figure came to their aid, and Zeus fought him for some time, before he realized it was Hercules, risen from his sick bed to help his friends. Zeus is deeply grieved by his folly.
- The orkish view on friendly fire is seen in Deff Skwadron, when the squad commander of deff skwadron chastises one of his gunners when he baulks at firing into a pitched dogfight where telling who is on which side is impossible. Essentially it boils down to "shoot at everything, and if you hit anything it must obviously belong to the enemy."
- In Fury: My War Gone By, Nick Fury and his partner Heatherly is stuck on a French base in Vietnam, then called French Indochina. They come under heavy assault by the locals, and the battle gets close and messy. Eventually, the locals are driven back. After the battle, Heatherly says he's pretty sure he shot a friendly.
Nick Fury: I'm pretty sure I did too. Sometimes it just gets like that.
- When under the effects of the Trigger Scent, X-23 enters a berserker state where she tears apart everything in her path, and when she's in her rage she blacks out entirely, and is completely unable to distinguish friends from foe. It's been exploited by villains on multiple occasions to force her to hurt people she cares about.
- Happens quite a few times in The Transformers. One notable example comes in the Christmas story "Cold Comfort and Joy". The Autobot Powermasters track down a group of robots who spoiled a town's Christmas festivities, assuming they're Decepticons, and it isn't until Joyride notices the Autobot symbol on the chest he's pounding that they realise their mistake. (The Autobots were just trying to join in the fun but the townspeople all went "Aargh! Giant robots!" anyway.)
- In Robyn Hood: I Love NY'' #3, Robyn and Agent Red are both sneaking into the same club. Not knowing who is coming, Red detonates a flashbang. Blinded and deafened, Robyn then attacks the person who threw the flashbang, not knowing it is Red.
- The Dressing as the Enemy tactic used by the German soldiers at Bastogne in Battleground forces the real American soldiers to do this a lot. One encounter between the American protagonists and some other Americans in a jeep leads to a comic exchange in which they're challenging each other to prove themselves by asking how the Brooklyn Dodgers did last season or who Ginger Rogers is dating.
- In the battle royale at the end of Blazing Saddles, The Waco Kid punches Black Bart before realizing who he is. He pats his cheek by way of apology and then throws himself back into the fray.
- Played straight in the German film Berge in Flammen ("Mountains Aflame", 1931), set in World War I in the Alps. Austrian soldier Florian Dimai, played by Luis Trenker (who also co-directed the movie and wrote the semi-autobiographical novel on which the screenplay was based) returns from a dangerous reconnaissance behind enemy lines with the news that the Italians are about to blow up a giant mine beneath the Austrian positions and is shot in error by one his own comrades who mistakes him for an approaching Italian soldier. He still delivers his message and the men leave the position in the nick of time before it is blown to smithereens, but in the epilogue set in 1931 Dimai has only one arm.
- Played with in The Longest Day. Allied paratroopers are given clickers used to identify each other without speaking (just as in Real Life in World War II) - two clicks will be answered by two clicks from a friendly soldier. A lone paratrooper hears an approaching person, clicks twice, and hears two clicks in return. He stands up in relief, and is shot and killed by the approaching person - a German soldier. The Reveal happens when immediately afterwards, the German soldier works the bolt action on his rifle - producing two metallic clicks.
- Played for Laughs in Black Hawk Down: Three Rangers have been separated from the convoy, and are making their way through the city (two machine gunners as a pair, and one rifleman on his own). The one rifleman gets shot at, and is quick to share his opinion of the two gunners.
[after being shot at]:
Twombly: Say who?
Yurek: It's Yurek! You almost killed me, you fucking assholes!
Twombly: ...well, uh, come to us!
Yurek: Fuck you! Come to me!
- Played straight in Hamburger Hill: a green lieutenant is shown to be having trouble locating his position on a map while calling in an airstrike. Huey gunships then fly in and gun down the advancing American soldiers.
- In the After-Action Patch-Up scene at the end of El Dorado, it's revealed that the injury Cole Thornton received in the leg during the climactic gun battle was from Mississippi's Sawed-Off Shotgun.
- In Joseph Vilsmaier's Stalingrad, during the assault on a factory, von Witzland's unit engages in chaotic close combat and one of his soldiers accidentally kills a comrade. Another one remarks that the hapless killer shouldn't feel too sorry, because this happens to everyone.
- Used in several scenes in Kelly's Heroes:
- Kelly's platoon is bombarded by their own side's artillery repeatedly, thanks to the incompetent Mulligan getting the coordinates wrong.
Big Joe: [yelling at Mulligan over the radio] No the Krauts are not here! We're here!
- German officer Colonel Dankhopf is shot by one of his own Tiger tanks after he drunkenly wanders over towards it during a battle and gets mistaken for an American.
- When the platoon is behind enemy lines, an American fighter plane attacks them repeatedly and destroys their Jeeps and halftracks, mistaking them for Germans.
Crapgame: Hey! Hey! That idiot's one of ours!
Big Joe: Oh. Our hero.
- Kelly's platoon is bombarded by their own side's artillery repeatedly, thanks to the incompetent Mulligan getting the coordinates wrong.
- This happens to Major Schroeder in Force 10 from Navarone after he gets taken prisoner by the Allied commando team. His men ambush them in the hall and shoot at his captors, but only succeed in accidentally killing him.
- At the end of Under Ten Flags (1960), a British officer who's a POW on the German raider notes the irony that he's dying from a British shell splinter (from the cruiser that's firing on them), and points out to Captain Rogge (who's tried to fight the war in a civilized manner) that such decency isn't possible in modern warfare.
- Exploited by 007 in Thunderball. Finding himself between two groups of the Big Bad's men, Bond takes a shot at each, then quickly ducks out of the way when they open fire in each other's direction.
Largo: Stop it you fools! He's got you shooting at each other.
- The Assignment (1997). The protagonist is a doppelganger for infamous terrorist Carlos the Jackal, so he's recruited for a CIA/Mossad intelligence operation. His impersonation works so well he's mistaken for the real Carlos by French anti-terrorist agents and has to shoot his way out.
Shaw: The French made it perfect for us. The KGB now think you're Carlos. They took the bait!Annibal: You fucking maniac. Jack, I-killed-four-men! (as Jack looks away) HEY, I DON'T LIKE KILLING OUR FUCKING ALLIES, ALL RIGHT?Amos: Policemen wind up killing other policemen. It happens. I'd rather have you here feeling guilty about them then to know that there's some meeting in Paris with them all sitting around feeling guilty about you.
- In Dan Abnett's Warhammer 40,000 novel Titanicus, Cally Samstag had the troopers flee after one of them sent a message. They are still tracked down by skitarii. When they ask for them to Get It Over With, the skitarii say they have sent for a rescue and then realizes that they thought it was an enemy.
- In Sandy Mitchell's Ciaphas Cain novel Death or Glory, when he made vox contact with Sergeant Tayber, Tayber refused to give him his position because he didn't know he was really a commissar, and went to meet him instead; this gives Cain hope that he has hit on a competent officer. Later, Lieutenant Piers is about to open fire on their orkish vehicles, and when Cain hails them, still demands that he prove it.
- In Lloyd Alexander's The Kestrel, a battle-mad Theo shoots a Regian soldier before he realizes it's actually his queen (and, to make it worse, his betrothed) Dressing as the Enemy.
- In Dan Abnett's Gaunt's Ghosts novel Only In Death, in an apparently haunted stronghold, the Ghosts repeatedly bring up guns only to discover they were about to shoot their own men. No friendly fire occurs, although sometimes because another soldier stops it.
- In Blood Pact, Criid attacks a figure in the streets; he wrestles with her until he can point out that he's Gaunt.
- In William King's Warhammer 40,000 novel Space Wolf, when Ragnar escapes the caves, he faces a lot of guns in the hands of Space Marines. Although he thinks they recognize him, he is very, very, very careful, because it would be irony indeed to escape the Chaos Space Marines to die at the hands of friends.
- In Grey Hunters, they find soldiers, and Ragnar spies on them to discover that they are loyalist. He is very careful about contacting them, in order to avoid provoking a fight.
- In Lee Lightner's Sons of Fenris, when Ragnar is leading Space Wolves in the jungle, they reach the city, and find that the comms don't work, and they are taken for enemy. Ragnar has to charge through the attack to make contact. Later, when Ragnar smells that there are other Space Marines in the city, he and the rest of the Wolfblade ready for combat, just in case.
- In Graham McNeill's Warhammer 40,000 novel Storm of Iron, the Chaos forces herd prisoners toward the Imperial outpost. They are slaughtered, and the forces learn the positions of the Imperial guns.
- In Graham McNeill's Warhammer 40,000 Horus Heresy novel False Gods, Davin's moon is so mist bound that Loken is always bringing up his gun to shoot before he recognized an ally. More seriously, remembrancer Petronella Vivar takes it upon herself to go to the battlefield, and her shuttle goes unrecognized and is fired upon.
- In Graham McNeill's Warhammer 40,000 Ultramarines novel Dead Sky, Black Sun, after a fight, the Unfleshed take Uriel and his companions prisoner because they might be friendly — though they think probably not.
- In The Killing Ground, when the Space Marines make contact with Imperial forces, they first scout them carefully; Pasanius assures Uriel that their machinery is well-maintained, which points toward Imperial forces, but they still meet them with some trepidation, as there is no way to be sure. Later when the Grey Knights arrive, they take Uriel and Pasanius prisoner — none too gently — because they might be tainted and so enemies.
- In Edgar Rice Burroughs's The Gods of Mars, John Carter, trying to escape, attacks the approaching jailor — only to realize that it wasn't the jailor, it was his own son. Briefly, he even thought he had killed him.
- In one battle in The Diamond Throne, a force masquerading as Pandion Knights is attacked by a force of legitimate Pandions. As both sides would be in the same armor design, the legitimate Pandions wear colored armbands to identify friend from foe.
- In Jim Butcher's The Dresden Files novel Dead Beat, Grand Theft Me makes this very difficult to figure out.
- In J. R. R. Tolkien's The Return of the King, the sight of the fleet causes panic in Gondor until its flag becomes clear.
- In The Children of Húrin, Túrin, having been captured by Orcs mistakes his best friend Beleg, who has come to rescue him, for one of his captors and kills him. This triggers a major Heroic BSoD.
- In H. Beam Piper's Lord Kalvan of Otherwhen, Kalvan discusses battle cries to keep their forces from attacking each other. At the battle itself, some of their foes attack others on their side; after it, Kalvan talks with one prisoner, who indignantly declares that he had been shouting his battle cry at the top of his lungs.
- In Wen Spencer's A Brother's Price, Jerin, escaping, threatens to shoot Cira. She barely manages to get past the gun; then she helps.
- In Endless Blue, Mikhail immediately deploys Reds to guard on the crash; when he is asked what if someone approaching was friendly, he says they will learn that they are not. He tones down the orders shortly. An officer complains that they can not use IFF — Identification Friend or Foe — to recognize anyone, and Mikhail orders maintaining radio silence, which will keep anyone from finding them.
- Terry Pratchett's Discworld:
- Night Watch has a group of the old City Watch defending Sam Vimes, while another group of Watchmen (led by an escaped criminal) are trying to kill him. The friendlies happen to be passing a lilac bush, so they each break off a blossom and stick it on their helmets. This becomes a tradition in later years, with the survivors of the battle wearing the lilac every 25th of May.
- In Interesting Times the Magitek terracotta warriors springing up beneath Lord Hong's army causes the soldiers to flee... towards the armies of his rival Lords who only joined forces because 7 barbarians had taken over The Empire. The soldiers assume that they're being attacked by Lord Hong and start fighting. It's noted later that these fights actually killed more of the soldiers than the terracotta warriors.
- Asked by a palace guard when Mort, channeling Death himself, tries to enter.
Guard: Friend or foe?
Mort: Which would you prefer?
Guard: ... Pass, friend.
- Another example, in Jingo. While Vimes is having a talk with 71-hour Ahmed, they are attacked by a random Ankh-Morpork patrol.
- In C. S. Lewis's The Silver Chair, having killed the Lady of the Green Kirtle, they set out warily into her underground kingdom — her subjects are setting off firecrackers, and they fear signals — but once they capture one to question, Rilian reveals that he killed "Her Ladyship", the subjects reveal they were under Mind Control, and matters are settled all around.
- In James Swallow's Blood Angels novel Deus Encarmine, many Blood Angels, driven into the Black Rage, fall blindly on each other — an effect that the survivors actually admit frightened them. When they counter-attack and take down the enemy ship, the Word-Bearers' helots are driven mad by the psykers' deaths and fall on each other — blocking the Word-Bearers' way, so they slaughter them, too.
- Part of the formula of The Hardy Boys series has the heroes, at the climax, briefly mistaking The Cavalry for enemy reinforcements.
- In E. E. Doc Smith's Triplanetary, in the Atlantis section, Phryges is held at gun-point by a woman while he is undercover — and he realizes it's his childhood friend Kinnexa. She insists on his turning around so she can check for a scar to be sure it's him.
- In Patricia C. Wrede's Mairelon the Magician, Kim is accosted as she comes out of the pub, and blacks his eye before she realizes it's Mairelon.
- At the end of A Good Clean Fight by Derek Robinson, a (British) SAS patrol is ordered to intercept the survivors of a German bomber that landed out in the desert. They do, and capture the crew. A (also British) fighter squadron has received the same orders, but when they reach the bomber they see that someone's been there before them. They follow the tire tracks — and thoroughly strafe the SAS patrol and kill everyone they see. It happened.
- In Andy Hoare's White Scars novel Hunt for Voldorius, the Raven Guard, seeing someone arrive, discuss the possibilities — not allies of the Chaos forces, since they arrived secretly, but they could be Chaos forces that are rivals, and they don't see any way they could be Imperial. It is fortunate that one White Scar scout made out some of the Raven Guard and voxed an abort to the Thunderbirds, and the Raven Guard intercepted it; there was nearly a fratricidal bloodbath.
- In L. Jagi Lamplighter's Prospero's Daughter trilogy, at one point, someone pursuing Miranda by boat suffers a fatal accident on rocks. Only later does she learn he was one of her brother's men, trying to warn her of something.
- In Robert E. Howard's "Beyond the Black River" Conan the Barbarian talks to a Pict in his own language to trick him ashore so he can kill him and steal his boat — to Bring News Back of the Pictish attack.
- In Poul Anderson's A Midsummer Tempest, trying to reach the royalist forces brings up great fears of this being a problem; Rupert thinks he should not try to cut his hair so he can prove who he is, quickly.
- In The Dark Tower series, Roland mentions that he and his best friend Cuthbert killed their friend Alain after mistaking him for an enemy scout.
- In Edgar Rice Burroughs's The Monster Men, Sing shoots at ships he takes for pirates, though he knows they might not be, because being taken by pirates is too horrible to risk.
- In Michael Flynn's In The Lion's Mouth, a secret espionage war has friendly fire accidents: one man is killed by another on his side, because of his cover. Later, Dominic Tight is targetted in an actual fight, where his invisibility cloak hides his identity.
- In Lois McMaster Bujold's Captain Vorpatril's Alliance, Ivan explains they still use dog tags to identify soldiers because implants might betray them to their enemies.
- Happens in accordance with historical incidents of friendly fire in Jeff Shaara's Civil War novels, Gods and Generals and The Last Full Measure. General "Stonewall" Jackson is shot in Gods by fidgety sentries and dies of complications. General Longstreet is shot in Measure right after worrying that one rebel unit's black uniforms make them look like Yankees, but he eventually recovers.
- Doom begins in Afghanistan where Fox company is lost in a mist. The company sees shadowy figures moving around and Lt. Weems panics and orders the Marines to attack. Arlene, the company scout, has gotten in close and confirmed that the men are unarmed monks. Weems refuses to listen, Fly tries to punch him out but fails, and Fox guns down civilians in a fog.
- At one point in The Wheel of Time series, Rand's attempt to secure the allegiance of the Aiel clans has caused a civil war among that race, and he has to put down the rebellious faction before they can lay waste to civilization. The Aiel on his side are convinced to wear armbands so that the non-Aiel forces know not to attack them; they take this as a great insult, as they can tell one clan from another at a glance from the cut of their clothing.
- Discussed in Ark Royal, where the titular old-fashioned armored carrier's sensors are so bad that the automated point-defense guns have a good chance of mistaking one of the carrier's own fighters for an enemy and shooting it down. Unfortunately, since the aliens' stealth systems are so good they can easily bypass a fighter screen to strike at the ship herself, the ship's CAG orders that at least one wing must always remain close to the carrier to protect it, despite the risk from the point-defense guns.
- A Sailor of Austria by John Biggins. Lt. Otto Prohaska receives orders to shell enemy forces in a small harbour that isn't even on his maps. He turns up at where he thinks is the enemy area and starts shelling it with the deck gun, doing only minor damage, when the lookout suddenly realises they're shelling their own troops, so they quickly submerge and get the hell out of there. Later Prohaska reads in a newspaper about how his submarine bravely attacked an enemy harbour, causing such massive damage that the cowardly enemy fled in terror. In the same paper is an article about the brave Austrian soldiers who sank an enemy submarine who opened fire on them while treacherously flying the Austrian flag.
- Later the German navy accuse him of torpedoing one of their mine-laying submarines that had gone missing, one that had his future brother-in-law serving on it as well. His fiancee doesn't hold it against him as accidents happen in war, but Otto lives with this doubt for years until he finally comes across proof that the submarine blew itself up with a malfunctioning mine.
- Another comic example is the sketch in Rutland Weekend Television where a guard asks a man in a carrot suit "Are you friendly or foeful?" The carrot man replies that a more correct challenge would be "Art thou friend or foeman-carrot?" After a lengthy discussion about the correct adverb of "foe", the carrot admits he's a friend.
"So we didn't need the bloody lecture on "foe" after all, then!""Only a friend will help you with your grammar."
- In the finale of Battlestar Galactica, in order to distinguish between friendly and enemy Centurions, the colonials use the simple method of slapping a red sash of paint on their friendlies, which had the advantage of making them look even more badass.
- The X-Files: Agent Scully, in an effort to salvage her career, is paired with a young up-and-coming FBI agent. Who shoots a murder suspect who turns out to be holding a camera. Not only that, the bullet goes through his body and hits Scully. One assumes his career took a nosedive after that.
- It's also a common trope for the show in general. The tagline is "Trust No 1" for a reason. It's very hard to keep track of who is friend and who is foe, especially since that changes from week to week.
- Played for comedy and subverted in Do Not Adjust Your Set. The exchange went:
Guard: Halt! Who goes there, friend or foe?
Guard: Uh...oh! [shoots]
Officer: [stumbles on-screen, speaking carefully] Well done, Foster...just checking. [collapses]
- Happened on Meerkat Manor, when the two halves of the drought-divided Whiskers clan were about to attack the "strangers" they'd spotted in the distance, but fortunately recognized each others' clan scent before any harm was done. Justified by meerkats' poor distance vision and intense territoriality.
- An episode of Mash ('C*A*V*E') dealt with the 4077th's issues with a well-meaning artillery barrage. It's not the only time it happens.
- Star Trek: Deep Space Nine:
- In "A Time To Stand", the crew are taking a captured Jem'Hadar ship on a covert mission when they are attacked by the Federation ship USS Centaur. Fortunately there is little damage on either side.
- And invoked in another episode, "Paradise Lost", where the USS Defiant is engaged in an inconclusive battle (neither side was ultimately willing to use enough firepower to destroy the other ship) by the USS Lakota, due to the latter ship's crew being given false information that the Defiant had been taken by Changelings.
- In "The Siege of AR-558", Sisko and his officers beam down to the titular planetoid to bring supplies to combat-weary Federation soldiers and are quickly fired on by said soldiers. Fortunately, their CO orders them to cease fire before anyone gets hurt.
- Star Trek: Voyager. Played for Laughs in "Message in a Bottle" when two squabbling EMH's are trying to work out how to pilot an experimental Starfleet spacecraft in the middle of a fight between Starfleet and Romulan vessels. At one point they launch a photon torpedo that loops past a Romulan warbird, slamming into the shields of a Defiant class vessel.
EMH Mk 1: You hit the wrong ship!
EMH Mk 2: It wasn't my fault!
EMH Mk 1: Then whose fault was it: the torpedo's? You're supposed to tell it what to do!
- Star Trek: Enterprise: During a space battle between Vulcans and Andorians, with the Enterprise joining the fight on the Vulcans' side, one of the shots hitting the Terran ship is clearly coming from the Vulcans (Andorian beams are blue; Vulcan beams are green; Terran beam are red — the color of their respective blood). This is not commented upon, though.
- In the Supernatural episode "Devil May Care" (S09, Ep02), Kevin shoots an arrow at Dean when he enters the bunker before he realizes who Dean is.
- In the Stargate Atlantis episode "Phantoms", Sheppard's team goes to an unfamiliar planet on a rescue mission and finds themselves under the influence of a Wraith mind manipulation device that makes them hallucinate. As a result, Sheppard thinks McKay and Ronon are enemies and shoots them both (nonfatally). This is played for laughs near the end of the episode.
Rodney: You shot me!
Sheppard: Yes, Rodney, I shot you, and I said I was sorry.
Ronon: You shot me, too.
Sheppard: [exasperated] I'm sorry for shooting everyone!
- On The 100, Clarke convinces Anya that she should work with the Sky People instead of fighting against them; Anya is killed almost immediately afterwards, shot by Sky People who didn't know she wasn't still their enemy.
- Part of the backstory of Flashpoint character Sam Braddock. He was a long-distance marksman in Afghanistan, taking out targets from over a kilometer away, which meant that he couldn't make out any detail about his targets and was relying on information from reconnaissance teams to be sure that everyone in the target zone was an enemy. For reasons that are never explained, on Sam's final Army mission, his best friend ended up in the target zone at the wrong time and took one of Sam's bullets. Despite the fact that he couldn't have known, the episodes where this is mentioned make it clear he's carrying an incredible amount of guilt over what happened.
- In Irish legend, when the hero Cuchulainn goes into "warp-spasm," he is invincible — but cannot distinguish friend from foe.
- Played for Laughs in an episode of The Goon Show in which Willium shoots at Seagoon and then asks "Friend or foe". And then there was "The Phantom Head Shaver of Brighton":
Eccles: Who's dat? Halt, who goes dere?
Ned Seagoon: Have no fear, I'm Q. C. Hairy Seagoon — defending council in the Nugent Dirt case. I have on me several documents of identification — including a letter of personal trust from the Commander of the British Army; a memo of recommendation from Mr. Anthony Eden, the Foreign Secretary; a special pass signed by Mr. Clement Attlee, Leader of the Opposition; and last but not least, a permit to go where I please signed by the Prime Minister the Right Honourable Sir Winston Spencer Churchill.
Eccles: Friend or foe?
- In The Hitchhiker's Guide to the Galaxy radio series, Arthur is asked this, to which he sensibly replies, "Do I know you?... Well, without knowing you it's hard to tell. I mean I quite like some people, others, not so much." He later goes on to explain that very few of his friends "have piercing red eyes, black armour, and laser rifles."
- The Tactical Shooting supplement for GURPS warns us that this is a very real possibility in a chaotic and poorly lit gunfight.
- Warhammer 40,000:
- Khornate berserkers are out for blood (for the blood god!) and skulls (for the skull throne!), and they don't care whose. This includes all the World-Eaters traitor Legion — among whom Kharn The Betrayer is particularly noteworthy, having attacked his own legion as well as the enemy when both sought shelter against deathly cold rather than fight on. Despite this, he's a pretty fun guy.
- And there's also the Chaos Dreadnought who every turn has a chance to go batshit crazy and turn all of his available weaponry on the nearest target regardless of affiliation, because unlike Loyalist Dreadnoughts, they don't get to sleep for the centuries between battles, they get their limbs and weapons removed and get chained to the wall, aware of every passing second.
- Orks as well, though in their case it's less "kill for the dark gods" and more "hah, lookit those gits gettin' shot". Orks are attracted to loud guns and enormous explosions, so if they come from their own side not matters little, being an acceptable risk in the endless cycle of fighting, looting, and shooting that is an ork's happy life.
- In in-game mechanics however, the trope is averted by the same vein as Warhammer, with no units being allowed to use ranged attacks upon units in engaged in a melee and risk hitting their allies. However, Blast weapons missing could potentially end up accidentally hitting allied units from scatter moving the targeting circle onto them.
- Warhammer: for balance reasons, units in melee can't be targeted by ranged attacks, averting this trope. Played straight with the Skaven, who as a race of backstabbing ratmen, can fire into melee (with a random chance of hitting friendlies).
- Many gamers will have a personal story of being toasted by an overeager ally with more fireball radius than he intended. Later versions of the games (especially those with magic-produced kabooms) even start adding abilities that allow true friendly fire; how about a raging inferno, 40 feet across, with built-in 5-foot safe squares in a random pattern?
- So, so true in most online shooters. If you never accidentally fired at your teammate, you probably never played a shooter online.
- This is particularly common in "real world" first-person shooters, particularly WW2 shooters. Often, the only difference between the uniforms worn by the soldiers on your side and those worn by the soldiers on the enemy side are a slight difference in the shade of khaki. In sci-fi shooters, you at least have more flamboyant, easily distinguished uniforms, or the enemy will be outright alien and easy to spot simply by their profile.
- Happens so often in Red Orchestra to the point that there exists a specific apology message in chat.
- On the other hand, in a few shooters enemies can hurt each other with their attacks, the so-called monster infighting popularized by Doom.
- Fortunately, many games give you the option of turning Friendly Fire off. Lag and collision detection glitches can also result in team kills while, say, firing on an enemy to assist with a kill if your teammate moves near your line of fire.
- Worse in Söldner, where every player could customize his outfit and color, meaning only the teamnames above their heads showed who was on your team. Enter a bug where sometimes a teammate won't have this blue name displayed...
- Call of Duty has this problem as well — it's surprisingly easy to get the game to not display a teammate's name over his head even as you're staring right at him, though thankfully there's normally no friendly fire. Then you enter Hardcore mode, where friendly fire is enabled, the name-tags are disabled, there's no radar to show teammates' locations unless a UAV or spy plane is in the air, and health is reduced to the point that a single bullet with pretty much anything is an instant kill. Getting kicked from the server for too much accidental teamkilling is not at all uncommon.
- Regarding Call of Duty, the single player campaigns have some of the same problems; the names of allied NPCs are often not displayed if you're not aiming at them or at a distance. The games try to acknowledge the inherent risk by allowing the player to accidentally/deliberately wing plot-relevant allies (who will often give a word of warning) or kill the occasional Red Shirt, but this isn't always consistent; add in some Artificial Stupidity, and you'll probably have a few unnecessary game overs on your hands.
- A.S.P. Air Strike Patrol DeconstructedTropes the "shoot anything that moves" aspect of Shoot Em Ups this way. Coalition forces and civilians are present throughout the game, and some missions will require you to make precise strikes on enemy forces in urban areas. Hitting friendlies or civilians will make international news, and damage public opinion of the Coalition. Do it enough, and anti-war protests will happen. Ultimately you'll earn yourself a Nonstandard Game Over as the Coalition is forced to pull out.
- In Fallout, you had to take a separate perk to have the computer mark your friends in green. Without it, you had to remember (or, in some cases, guess) who was on your side. Or you could just "check". If the game tells you "Ian", "Tycho", "Katja" or "Dogmeat", chances are good that they are friendly.
- The main reason to play as an Engineer in Mass Effect or Mass Effect 2 is to scramble enemy robots' IFF targeting and make them go on a berserk rampage through their own side.
- This is also how Samara greets Shepard for their first meeting in Mass Effect 2.
- In Fable, firing on a neutral character causes them to decide that the player is trying to kill them, and they promptly attack.
- Fable has a huge problem with this. Trying to win any large-scale battle with non-scripted allies is virtually impossible because they end up flashing red any time the player hits them- even if it's in such a way that neither the player nor the ally has any way of knowing where the shot came from!
- The Elder Scrolls:
- Throughout the series, allies and escorts with ranged attacks or spells have no compunction against using them, even if you are current between them and their target. This gets even worse if they have large Area of Effect spells...
- This is one of the contributing factors to Morrowind's notorious Escort Missions. The Suicidal Overconfidence of your escortees mixed with their Artificial Stupidity leads to them running off to attack every enemy in sight. If the enemy doesn't outright kill them, a stray blow from you likely will. If they survive it, there is a good chance they will then turn on you for attacking them. Either way, mission failed.
- Oblivion attempts several methods to downplay this trope. For one, those you are escorting are typically tagged as "essential", meaning they can't be killed, only knocked out. Additionally, the AI is a lot more understanding with accidental hits (with NPCs just admonishing you for being sloppy, unless you hit them quite a few times in a row). Finally, Oblivion includes a method for yielding to NPCs you've accidentally made hostile.
- The original Diablo game had friendly fire enabled.
- It's quite difficult to avoid hitting fellow survivors in Left 4 Dead (well, unless you're the AIs). There's even an achievement for getting through a campaign without any friendly fire incidents.
- Because the AI bots fire magic bullets. As of May 2017, 4% of the players have acquired the achievement badge for Safety First.
- In Wing Commander: Privateer, it's trivially easy to fall afoul of this with the starting radar, which doesn't give target types any color coding; the militia forces fly the same ships (with different color schemes that are hard to notice until you're right next to them) as the pirates and Retros, further compounding the problem. More advanced radar models color-code contacts, making it much easier to determine who is or isn't a legitimate target.
- In the main games, for the most part your opponents will be flying ships entirely different from your own side's, so it's easier to tell who's who. This doesn't, however, help too much if your wingman flies right into the path of the torpedo you just launched, resulting in an insta-kill of said idiot and everyone else declaring you a traitor, in all but the very first game (where there's no penalty for killing your wingman).
- On a related note: during a mission briefing in the original game, one wingman "Maniac" is so much trouble that the player is given permission to shoot him if he gives you too much hassle. There is also a Friend or Foe missile used throughout the series that locks onto targets if it doesn't broadcast the right friendly comm code, however the comm system can get damaged in fights.
- In the main games, for the most part your opponents will be flying ships entirely different from your own side's, so it's easier to tell who's who. This doesn't, however, help too much if your wingman flies right into the path of the torpedo you just launched, resulting in an insta-kill of said idiot and everyone else declaring you a traitor, in all but the very first game (where there's no penalty for killing your wingman).
- Taken to an extreme in Team Fortress 2. While it is very easy to see who is friend or foe due to the brightly colored team uniforms, the Spy class has the ability to disguise as any other class and in the process take on the name of another player. As the Spy also has an instantly lethal back-stab attack and it's not always too easy to notice the spies on behavior alone, it has become common to "spy-check". That is, shoot at your own team, preferably at close range. Anyone who dies or starts running, IS A SPAH!. This is because you can not hurt your own team. The best class for spy-checking is the Pyro, as a quick puff of flame will render both the Spy's disguise and his invisibility watch useless. Pyros are in fact expected to set fire to anyone and anything in order to find spies, and a Pyro who does not do this will most likely be subject to a spy-check himself.
- Averted in the Spy's own "Meet the Spy" video. The Soldier's point-blank shotgun blast would have been a perfectly valid tactic in game, resulting only in a BLU spy annoyed at being interrupted mid-monologue. Instead, the Spy's head explodes in a shower of Ludicrous Gibs.
- Averted in Command & Conquer: Red Alert 2 and Red Alert 3, Allied Spies and/or Imperial Sudden Transports can disguise themselves as enemy units, but will never be mistakenly fired on by their own side. The only way for an enemy to attack them without using scouts to break their disguise is to force-attack (explicitly give orders to attack, as units without orders will not engage them). Yuri's mind control towers, however, immediately FaceHeel Turn spies as soon as they hit their effective range.
- During the blackout at night during a thunderstorm in Modern Warfare 2, there's a very intense scene when a lightning strike shows a group of soldiers crossing the street some 30m in front of the squad. They don't reply to the code sign by Sgt. Foley, and suddenly guns are firing everywhere. Thankfully, it turns out they were really foes.
- Later on, they once again run into an unidentified soldier, who once again fails to give the correct response: The unidentified American runner frustratedly announces that he can't remember the response, and the situation is defused without incident.
- Some stages in the Gauntlet series of games had this, where your shots could either stun or even harm other players.
- Side-scrolling beat-em-ups, such as Final Fight, also have this. Even ones that did not (such as the Teenage Mutant Ninja Turtles or X-Men games) would have certain special wild attacks (respectively, environmental attacks and hurled enemies) that could harm other players.
- Doom had friendly fire in co-op mode. Much more famously, any monster with a projectile could incite a riot by accidentally hitting its allies, which would cause them to forget all about the player and kill each other. They don't really notice if one of their buddies wanders into the line of fire. Quite a bit of Doom strategy is based around tricking enemies into hitting each other.
- Star Fox 64 had a mission on Katina that, in addition to being a Shout-Out to Independence Day, involved assisting a Cornerian Defense Force base's fighter compliment in fending off Andross' forces. The problem — Andross' fighters are designed nearly identically to the CDF "greenies", and they are both easy to destroy with the Arwing's lasers. Fox's CDF friend Bill will not hesitate to call Fox out if he shoots down a CDF fighter.note
Though rare, it's possible for the rest of the Star Fox team to shoot down the CDF fighters as well.Peppy: Enemy down ... Wait! That was one of ours!
- This is a major danger in the Total War series, particularly with siege units.
- Set Dragon Age II to Nightmare difficulty level. Put a two-handed warrior with a BFS and a blaster mage with area-effect spells in your party. Let the AI control them while you muddle around as some other character. Watch the Total Party Kill ensue.
- Even though friendlies are highlighted green and hostiles red, it's still easy in World of Tanks to accidentally shoot a friendly, either through people driving through your line of fire, or simply being jumpy and shooting at the tank that suddenly was in your sights.
- Artillery is the worst offender due to large blast radius, inaccurate gun, long shell traverse time and fairly low skill requirement. It can be avoided by not sticking to enemy tanks, but it tends to be the easiest way to defeat T Ds and heavies with a lighter tanks.
- Chivalry: Medieval Warfare has serious problems with this, mostly because all battles eventually turn into multi-man melees with archers firing into the fray. And when you swing any sort of weapon into a fray that size, you're eventually going to chop your ally's head off by accident. Archers don't have it any better, and unless you're really good a sizeable portion of your arrows will end up adorning your pals. Even with proper caution taken it's very, very hard to avoid decking someone on your side during any battle bigger than a three-on-two.
- As per the Chivalry example above, it's also possible to accidentally hit allies with projectile weapons in Mount & Blade. Don't fire/throw into melee, it's just not going to end well. Fortunately, melee attacks can't harm your allies, though weapon swings will probably bounce off them (similar to swinging at a wall, for instance).
- One of the more embarrassing things to happen to players using howitzers in World of Tanks is this—because howitzers (including artillery guns) are both hideously inaccurate and devastatingly powerful, there's very few arty players who haven't accidentally teamkilled an ally thanks to the terrible accuracy on their gun.
- Alternatively, you could have your sights on an enemy that sat still long enough for your crosshair to lock in a guaranteed direct hit, only for an ally to chase them off after you've fired, then just so happen to stop right in the middle of your aim. Direct hit, ally goes kaboom, see you back at the garage.
- Light tanks tend to be the biggest receivers of this trope. Not just because of artillery, but because they can be so busy running circles around Tank Destroyers or Heavies, that they aren't paying attention to the guns of their own team-mates. This can result in many cases of Friendly Fire while team mates fire on enemy tanks while unaware that an allied Light Tank is about to come screaming around like a jackrabbit on crack.
- In World of Warships, Torpedoes are basically addressed "To whom it may concern" as missed torps that haven't sputtered out or hit their intended mark can be just as lethal to an ally, as they can to an enemy. There's even been cases of particularly careless carriers with torpedo bombers sinking themselves with their own torpedoes.
- This can be a bit of a problem in some flight simulators, especially those taking place in the Cold War Middle East. For instance, in F-15 Strike Eagle it is possible to play missions against Iran, who can and will field the American-built F-4 Phantom and F-14 Tomcat. The problem is that, since you play an American strike fighter, your allies are also in Phantoms and Tomcats. Any pilot with a too-itchy trigger finger who doesn't obey the rules of engagement (identify, then engage) will come home to find a nice neat court-martial summons waiting for them.
- Girl Genius: Agatha gets questioned before she gets helped.Context (some spoilers)
- In Kevin & Kell, the hunting team takes part in a "blind stalk", in which they hunt in total darkness, guided only by their sense of smell. Vin, a jealous member of the team, tries to get revenge on Rudy by putting prey pheromones on him, and Rudy manages to avoid his teammates long enough to lure in a deer (who mistakes him for a doe) and take his antlers. It initially appears that Vin was mistakenly eaten by Rudy's teammates, but it is later revealed that he was abducted after stumbling onto the Great Bird Conspiracy.
- In American Barbarian, Two Tank Omen sends his prisoners toward his enemies, leading them to think the prisoners are his allies -- and they attack them.
- In Freefall, satellites use IFF to differentiate ships from space hazards.
- Comes up regularly as a topic of discussion in Schlock Mercenary, usually as an explanation for why Schlock can't have more or bigger guns. Exploited in an early storyline: when hired out by two local gangs at once, they get the gangs to wear IFF tags to avoid being inconveniently shot by their mercs (who "don't know your 'homeyz' colours from crapstains", direct quote)...and then use the tags to make it easy to round up all the gang members and complete a contract for local law enforcement.
Maxim 15: Only you can prevent friendly fire.
- In the TGWTG Year One Brawl everybody had trouble determining who was on whose side—one time The Nostalgia Critic asked if That Chick with the Goggles was on his side; as she said no he immediately punched her.
- The first casualty in Red vs. Blue? Church, of the Blue army. The shooter? Caboose, also of the Blue army. Church is not pleased.
- The Wild Thornberrys had this in one episode, where for a battle, Eliza and Darwin placed two groups of monkeys, one with long tails and one with short, in coconut-shell armor. When the monkeys went to fight, they couldn't tell friends from foes and attacked both, to prove Eliza's point that they weren't that different, and the whole "Tails vs. No tails" thing was completely ridiculous.
- Avatar: The Last Airbender seems to have a villain-induced variant: In the episode "Zuko Alone", one of the soldiers mentions that the Fire Nation will often put captured prisoners in Fire Nation uniforms before placing them on the front lines of an assault unarmed, causing their own comrades to unknowingly slaughter them, believing that they're the enemy.
- In "The Boiling Rock", Sokka is disguised as a prison guard, and becomes victim to this trope, twice.
- Transformers Animated episode Lost And Found, Those Two Bad Guys Blitzwing and Lugnut are fighting the Autobots at the bottom of a lake. When the lake gets muddied up from the fighting, Lugnut sees a dark figure and punches it...
Blitzwing: Whose side are you on?
- My Little Pony: Friendship Is Magic features the Changeling, a species of shapeshifting monster. In one episode, they disguise themselves as the heroines and engage them in a fight, where it is hard to tell who is fake and who is real.
- The animated Punky Brewster episode "Double Your Punky" has the titular girl battling an obnoxious clone of her that Glomer accidentally created from a photograph. Glomer is unable to tell which is the real Punky so he can zap the other back into the photo. Punky's dog Brandon picks her out immediately, recognizing her scent.
- The Hair Bear Bunch: In "King Klong Vs. The Masked Marvel," Botch asks the drivers of an arriving truck if they are friend or foe. They're from a rug cleaning company, so Botch lets them pass as friend.
- Season 5 of Samurai Jack: Many people whom Jack had met and inspired nearly attacked Ashi, as she could have been mistaken for one of Aku's servants.
- The episode "Snafuperman" of the WW2 soldier's educational cartoon Private Snafu had Snafu refuse to read his maps or field manual, and gets magicked into a Captain Ersatz of, as the name suggests, Superman by the Technical Fairy. He attempts an air raid on Washington DC under the misconception it was Berlin, and attacks an American tank thinking it's a Japanese one.
- The rules of heraldry exist to avert this trope.
- "At least" would be appropriate. People playing "scenario" paintball (in the woods with ambushes and camo, as opposed to open field with team-colored shirts and short-range engagements) and airsoft realize very fast how the only thing more accurate than incoming enemy fire is incoming friendly fire indeed.
- During the Battle of Chalons in 451 AD, after the Visigothic King Theodoric had died, the Visigoths and Romans had managed to fight Attila the Hun to a standstill into the night. In the darkness, Thorismund, the new Visigothic king, was nearly killed when he rode toward Hunnic lines thinking they were his own soldiers. Luckily for him, he realized the truth in time and booked it. This was mere hours after his father died. The Visigoths almost lost two kings in a single battle.
- It has been estimated that during any particular war since the dawn of the gunpowder era, as much as ten percent of the casualties were the result of this trope.
- One urban legend concerning an event in the Hapsburg-Ottoman wars of 1787-91 ramps this up to Epic Fail levels. Between drunkeness, lack of communication, and darkness two Austrian forces both end up thinking they are under Turkish attack; when the Turkish army showed up a couple of days later they find 10,000 casualties and the rest long gone so they take the nearby town with hardly a shot.
- Confederate general Stonewall Jackson was shot by some of his own men and mortally wounded when they mistook him for a Yankee in the dusk when he returned from a reconnaissance ride late during the battle of Chancellorsville (1863).
- This was a real problem for much of The American Civil War. Confederate soldiers in particular tended to wear non-standard uniforms, due to their government generally being less organized and specifically having serious problems supplying the troops. If you didn't have an overcoat you might take one off a dead or captured Yankee. Combine that with poor communications in a pre-radio era and the huge amounts of smoke produced in combat, and the general confusion caused by combat, and Friend Or Foe happened many times.
- During World War I, being shelled by your own side's artillery was such a big and common hazard, that in the German army there was a much-used saying: "Der schlimmste Feind der Infanterie/Das ist die eigene Artillerie" (The worst enemy of the infantry is the own artillery). The fact the general method for attacking enemy positions during the war was closely behind artillery shelling them certainly did not help.
- A deliberate version happened on the last day of the war, when one artillery battery kept firing on the Germans despite having been told the armistice had been signed. It took the threat of being fired on by allied artillery to get them to stop shooting.
- World War II also had its share of incidents:
- The United states did field tests of the practicality of camouflage uniforms. By this I mean they took a handful of infantry, fitted them with uniforms, put them on the front and see how things turned out. Well, the Germans were the only ones in the theater that had their infantry use camouflage uniforms in appreciable numbers. With that knowledge and the fact that it's on this page, it shouldn't be surprising that most the infantry involved in the test decided to trade in their experimental uniform for the standard issue.
- In Antony Beevor's book D-Day: The Battle for Normandy he retells a German joke (from the fighting on the Italian peninsula) made at the expense of the RAF, Luftwaffe, and USAAF —>"If British planes appear, we take cover. If the Luftwaffe appears, nobody takes cover. And if the Americans show up, everyone takes cover."
- Bombings by mistake, especially by US aircraft, seeing as there were so many of them, were deadly and common. The highest ranking US general killed in the European Theater of Operations, General Mc Nair, was killed while visiting the front when his observation post was bombed by B-17's by mistake.
- Units engaged in secret operations under cover were always in danger of being attacked by mistake. The Doggerbank, a formerly British merchant ship used by the German navy for covert operations, was sunk by a U-boat mistaking it for a British ship, with loss of all but one of the crew.
- A very awkward battle from Estonia: As it happened, the Soviet Union and Nazi Germany were both invaders. While the Soviets forcefully conscripted Estonians in 1939-40 and in 1944-45, the Nazis only took volunteers in 1940-1942 until in 1943 they conscripted every able-bodied male into the SS, leaving the Soviets with just the old men and the kids coming-of-agenote ; either way, there were entire units of Estonians on both sides. During a particularly dark night, one of the Soviet-Estonian companies encountered a Nazi-Estonian company while marching through the forest.
Since both sides spoke Estonian, neither unit realized they were marching with the enemy—but when they did, all hell broke loose. Due to low visibility, the soldiers dropped their weapons, grabbed bayonets or knives and then held their weapon in one hand and with the other reached to touch each others' heads under the helmets. This is because the Soviet conscripts had shaven heads while the German army let the volunteers' hair be—so they determined who was friend or foe by haircut.
You could say it was the most awkward and largest Knife Fight in military history.
- Operation Husky: 144 C-47s were on approach for a night-time paradrop operation in Sicily but were fired upon first by Allied ships and then ground forces. A German air attack had occurred just minutes before the C-47s were arriving near the island and the naval AA gunners were simply too nervous to think first and shoot later.
- Operation Baseplate: 900 German fighters and fighter-bombers were launched in a surprise attack to destroy allied airfields in the Low Countries. The attack had failed with 300 planes and 237 pilots lost. Many of the casualties were caused by the secretive nature of the operation which resulted in much of the German Army and Navy in not being informed of a German Air Offensive which in turn led to many German AA batteries opening fire on their own planes.
- The Royal Navy cruiser HMS ''Sheffield'' was subject to this not once, but twice during World War II. The first time was when she was participating in the hunt for the German battleship ''Bismarck''. A squadron of Fairey Swordfish torpedo bombers had been sent to attack the Bismarck, but not been informed of the position of the Sheffield, and attacked the Sheffield. Luckily, the torpedoes had been armed with highly-unreliable magnetic detonators, and most of them exploded prematurely.
The second occasion was during the Battle of the Barents Sea, when the Sheffield was mistaken for the German cruiser Admiral Hipper...by the two destroyers assigned to escort the Hipper. The Sheffield did not make a similar mistake, and sank one of the German destroyers.
- The Polish submarine ORP Jastrząb ("Hawk") was escorting an Allied convoy to Murmansk when on May 2, 1942 it was attacked by Allied surface ships. Five crew members were killed and 6 others wounded. The submarine was severely damaged and was scuttled at sea. To this day there is dispute among historians as to who was really at fault for the friendly fire incident.
- This was a problem during the Warsaw Uprising. Polish fighters would scavenge German weapons and equipment including helmets and clothing. In the chaos of urban fighting it was often hard to tell whether someone running toward you was a German or a fellow resistance fighter dressed in a German camouflage coat.
- In WW2, there were "natural enemies" that would often attack each other on the flimsiest of excuses. Ships viewed aircraft, submarines, and small torpedo craft as to be shot at until proven otherwise, knowing that their best defense was to engage as early as possible to disrupt an attack. Fighters would view other single-engine aircraft with great suspicion. Submarines thought that anything small with visible guns was an enemy destroyer until it proved otherwise. Torpedo boats tended to see anything that floated as a valid target. Bombers viewed any single engine plane approaching them as a reason to open fire.
- One issue in air-to-air combat in Europe was that the American P-47 Thunderbolt had a very similar profile to the German Messerschmitt Bf 109, making distinguishing between the two difficult under combat conditions.
- Operation Cottage: In August of 1943, a combined force of American and Canadian troops launched an invasion of the Japanese-held island of Kiska. However, inaccurate intelligence meant the Allies didn't know that the Japanese had abandoned the island two weeks earlier, and rough terrain and foggy weather led to friendly fire incidents that resulted in 32 soldiers killed and another 50 wounded.
- Of the total landing force, approximately 35,000 strong, the Allies suffered more than 300 men as casualties and additional 1,500 as wounded over the operation. Apart from friendly fire, some were due to mines and booby traps left behind by the Japanese, but still, losing nearly two thousand men from the ranks on an island with exactly zero enemies present takes some trying. No wonder this one doesn't show up in the history books all that often.
- The Battle of Los Angeles: In February of 1942, war nerves and a misidentified weather balloon led to US Army anti-aircraft batteries in and around Los Angeles thinking they were under attack by Japanese bombers and firing into the clouds in response. 5 civilians died as an indirect result (3 from car accidents caused by the chaos and 2 from heart attacks), and several buildings and cars were damaged by falling shell fragments.
- This became an issue given the number of captured Allied tanks and tank destroyers that the Germans made use of. There was also an experiment in modifying Panthers to resemble American M-10 Wolverine tank destroyers, including American-looking paint jobs.
- A number of friendly fire incidents have happened in Afghanistan during The War on Terror:
- American-on-Canadian: The Tarnak Farm incident of April 2002. A U.S. Air National Guard F-16 mistook Canadian Army soldiers for Taliban fighters with anti-aircraft weapons. The farm had previously been used as a firing range by the Taliban, but was now being used by the Canadians for anti-tank and machine gun exercises. Although denied permission to attack by the controlling AWACS, Major Harry Schmidt believed the soldiers on the ground were targeting his flight leader, and bombed them in response. This cost the lives of four soldiers while wounding eight others.
- British/American-on-Afghani: During April 2006, British convoy called in an airstrike from American warplanes on Afghanistan police officers, mistaking them for attacking Taliban forces, killing one and wounding twelve. Note that in this case, the U.S. pilots were attacking as specified by the British, and not making an error of judgment of their own.
- British-on-British: In Sangin Province during August 2006, an RAF Harrier was called in to assist British troops during a firefight with the Taliban. The Harrier strafed the British instead, missing the enemy by 200 meters. This angered Major James Loden of 3 PARA, who called the RAF "Completely incompetent and utterly, utterly useless in protecting ground troops in Afghanistan." Some British paratroopers have even said they prefer American air support to the Royal Air Force.
- American-on-British: In a case of Poor Communication Kills, one of two American F-15Es called in to support a platoon from 1 R ANGLIAN dropped a bomb on top of the unit, killing three soldiers. The forward air controller in the platoon, Sergeant Mark Perren, was not issued a noise-reduction headset; the platoon was under heavy fire by the Taliban, making it hard to hear radio transmissions. When the F-15E pilot repeated misheard target coordinates for confirmation, Sergeant Perren wound up confirming his own location as the target.
- British-on-Danish: In Helmand Province during September 2007, British soldiers fired Javelin missiles at a unit of Royal Life Guards, killing two of them. The British soldiers had mistakenly identified the Royal Life Guards' camp as a Taliban hideout, and requested permission to attack. The Royal Life Guards, not realizing they were the ones being targeted, granted permission.
- Dutch-on-Dutch/Afghani: During January 2008 in the Uruzgan Province, a unit of the Dutch Army attacked a composite group of Dutch and Afghan soldiers that they had mistaken for the Taliban. Two Dutch and two Afghani soldiers were killed before the firefight ended.
- American-on-British: In January 2008, two Apaches, one British and one American, were called in to support a unit of Grenadier Guards and Afghan forces fighting the Taliban in the Helmand Province. The British Apache opened fire on the Taliban, while the American Apache attacked the Grenadiers. Only one person was wounded. After the incident, a high ranking British Army officer claimed that in contrast to the UK's full-time professional air forces, most American pilots are merely reservists, implying that this is why British-on-American friendly fire incidents never happen.
- British-on-British: Later that year in July, a British WAH-64 Apache was called in to support a unit from 2 PARA against Taliban fighters. After attacking the Taliban positions, the Apache mistook the 2 PARA unit for more Taliban and opened fire, wounding nine of them.
- German-on-Afghani: In early 2010, a unit of German soldiers arriving at the scene of an earlier firefight where the Taliban had ambushed a bridge-laying and mine-clearing operation encountered Afghan Army soldiers in civilian vehicles. After the Afghanis ignored an order to stop, the Germans fired on them, killing six of the soldiers.
- American-on-Pakistani: In November 2011, a joint 150-man U.S. and Afghani unit came under fire and called in an airstrike. Miscommunication between U.S., NATO, and Pakistani forces led to two Pakistani border posts being destroyed, killing 25 Pakistani soldiers.
- American-on-American: This is what happened to Army Ranger Spc. Pat Tillman in Afghanistan, 2004. Tillman's unit was ambushed and split in two during a patrol and his section moved ahead to get into a better position to provide support. The other part of the unit mistook the Tillman's section for the enemy and fired on them killing tillman and an Afgani soldier. Tillman was also a professional football player, making the situation even more delicate for the U.S. Armed Forces.
- In 1796, Amédée Laharpe, a Swiss general fighting for the French Republic, was mistaken for an enemy officer while conducting a reconnaissance at dusk and killed by his own soldiers. Made even more cruel by the fact that he was condemned to death in his home country for supporting the Revolution, and had to leave everything to serve France.
- Napoleon's Grand Army included Hanoverian battalions, who wore the same red coat as the English did. Most of the casualties among Hanovrians serving in the Peninsula were caused not by the Spanish, Portuguese or English, but by their French allies mistaking them for English. In particular, General Marbot tells the story of a Hanovrian battalion at Fuentes d'Oñoro sent to defend a vital spot... and shot at by both the English and the French who were sent as reinforcements. They held the position for several hours. Similar misfortunes happened to the Saxons whose uniforms looked like those of the Austrian, notably at Wagram.