When Creator/OrsonWelles needed to come up with a HalloweenEpisode for the October 30, 1938 broadcast of his CBS Radio program ''Radio/TheMercuryTheatreOnTheAir'', he decided to adapt the Creator/HGWells 1898 novel ''Literature/TheWarOfTheWorlds'' to a contemporary American setting. Rather than staging a regular radio play like all of the previous Mercury Theater broadcasts, for this episode the program aired what seemed like a regular night of music, until reports came over the air of strange phenomena on the surface of Mars and what seem to be meteorites landing in locations across America...

By the time large alien tripods emerged from the cylindrical meteorite and began destroying the American countryside, many listeners believed that the events taking place were really happening, and panic ensued. Or so the UrbanLegends say, at least. In fact, there was little to no actual panic, and the breathless reports that ran in the next day's newspapers were an attempt by newspapers to discredit radio--see NewMediaAreEvil below. Welles himself ended the program by saying that the program was little more than "dressing up in a sheet, jumping out of a bush, and saying 'Boo!'" and suggesting that the audience shouldn't be taken in by make-believe stories on the radio.

The one-hour program became a media sensation. Welles and his show were instantly internationally famous. The Campbell Soup Company jumped at the chance of becoming the sponsorless show's underwriter, and ''The Mercury Theater on the Air'' was renamed ''The Campbell Playhouse''. Whether or not Welles used the format to [[ForTheEvulz intentionally troll radio listeners]] is still up for debate, but the show made him a star, and led before too long to a movie contract, and ''Film/CitizenKane''.

The broadcast was actually [[http://www.war-ofthe-worlds.co.uk/war_worlds_quito.htm recreated in 1949 in Quito, Ecuador]] by director Leonardo Pez, ''definitely'' as an intentional prank, although not on the diabolical level that's been attributed to him. A huge riot erupted when listeners were finally told it was a gag. An angry mob with TorchesAndPitchforks set fire to the station, with 100 workers trapped inside. Seven people died. It was tried again in [[http://www.youtube.com/watch?v=g-oTTyGOkIg an updated version by WKBW]] in Buffalo, New York in 1968. [[http://www.youtube.com/watch?v=H1A0R1vldv4 Conceived]] by engineer-director Dan Kriegler and program director Jeff Kaye, it used the station's news staff and contemporary music and commercials and put the action in nearby Grand Island. Instead of a script, Kaye wrote out a series of events and had the news people read them as they would normally. In spite of fairly frequent "this is a dramatization" announcements, the show's format meant that people who tuned in late were going to think, at least for a few minutes, that it was real. A local newspaper, several police officers and the Canadian National Guard (which sent troops to the border) were among those deceived. [[http://www.youtube.com/watch?v=eXTEUM4OF7Q WKBW updated the format again and rebroadcast the show in 1971]].

The incident was dramatized in the 1975 TV movie, ''The Night That Panicked America'' co-starring JohnRitter, and it was touched upon in feature films like ''Film/RadioDays'' by Creator/WoodyAllen. It was analyzed in a [[http://www.radiolab.org/story/91622-war-of-the-worlds/ hysterically funny episode]] of NPR's ''Radio Lab'' in 2008, talking about the power of mass media and humanity's need for storytelling.

This incredibly innovative broadcast is the TropeMaker for DeadlineNews, PhonyNewscast, ThisJustIn, WeAreExperiencingTechnicalDifficulties, and WeInterruptThisProgram.

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!!The radio version contains examples of:

* AdaptationalBadass: The Martians, despite going up against more contemporary military technology (United States National Guardsmen equipped with [[GasMaskMooks gas masks]] and [[GatlingGood machine-guns]], military airplanes, etc.), manage to prove much more durable and threatening than in the original novel, and ''without'' having the force-fields they are depicted with in later film adaptations.
** For example, only ''one'' fighting-machine is brought down in combat [[hottip:*:In the book, one is gunned down by artillery fire, and two or three others are destroyed by a warship]], and it took an artillery barrage ''and'' a bomber plane [[HeroicSacrifice crashing into it]] to eliminate it. Also, the Black Smoke is deployed ''before'' said machine is destroyed, and it's shown to render gas masks ''useless''. And the real kicker is that the very first fighting-machine deployed by the Martians was pitted ''alone'' against an army of 7,000 National Guardsmen that were all using rifles and machine-guns, and left only ''120'' known survivors.
* AfterTheEnd: The last third of the one-hour show quits the PhonyNewscast format, and follows Pierson as he writes in his journal about his harrowing trip from Grover's Mill to New York City. He sees one living person the whole way.
* AndNowForSomethingCompletelyDifferent: About forty minutes in, the narrative changes completely to the aforementioned professor writing in his journal, and then briefly follows the professor and a stranger discussing Martian theories before returning to the journal again.
* AudioAdaptation: Of the famous novel.
* BattleDiscretionShot: When the first of the Martian fighting-machines rises from the cylinder, the radio feed from the National Guard stationed at Grover's Mill is conveniently cut short ''right before'' the soldiers open fire on the machine, and we are instead treated with a report on the aftermath of what turned out to be a CurbStompBattle (that the ''Martian'' won) from the CBS studio.
* CirclingVultures: They draw Pierson's attention to the corpses of the Martian invaders, lying around an abandoned New York after the Martians died from Earth-bound microbes.
* CommercialBreakCliffhanger: Averted. As ''The Mercury Theatre of the Air'' didn't have a sponsor, there didn't need to be a break in the program for advertisements; this helped keep up the {{Kayfabe}} of the broadcast. The only break acts as a transition between the faux-radio program and Pierson's AfterTheEnd narration.
* ContrivedCoincidence: Phillips the news correspondent conducts an interview with Professor Pierson live on the air, discussing the mysterious gas explosions on Mars. Then objects are observed to be falling from the sky and landing in rural New Jersey--just a few miles from the observatory, conveniently allowing Pierson and Phillips to go there and report.
* DeadlineNews:
** Carl Phillips, reporting live from Grover's Mill, is burned to death mid-sentence by a Martian heat ray.
** The reporter in New York narrates the advance of the Martian tripods until he is killed by their poison gas. The broadcast goes to dead air, then one voice comes on, repeatedly asking if anyone is out there.
* DecoyProtagonist: At first, Carl Phillips the news reporter appears to be this story's counterpart to the unnamed protagonist of the novel, with Professor Pierson the astronomer being the [[SacrificialLamb Ogilvy]] stand-in. Then it gets subverted, when Carl Phillips is found incinerated by the Martians' Heat-Ray, and Pierson fills the role of protagonist after being shown to survive the attack.
* EmergencyPresidentialAddress: Averted by ExecutiveMeddling. It was originally intended for the unnamed Secretary of the Interior to be President UsefulNotes/FranklinDRoosevelt, but CBS objected to this detail. That didn't stop Welles from having the actor imitate Roosevelt's voice.
* FaceDeathWithDignity: The radio reporter in New York, who narrates the advance of the Martian tripods into the city, knowing perfectly well he's going to die. ("This is the end, now.")
* {{Foreshadowing}}: The opening narration, adapted from the beginning of the novel, muses on how we were watched by the Martians as we might watch "the transient creatures that swarm and multiply in a drop of water". In the end it is those creatures that destroy the Martians.
* FoundFootage: A UrExample and perhaps the only radio version of this trope.
* KilledMidSentence: The at-the-scene radio reporter, Carl Phillips. Or, at least, the on-site radio equipment is destroyed while he's in mid sentence. (His charred remains are later identified.)
--> [describing the Martian death ray] "...coming this way, about twenty yards from my ri--"
** The pilot who crashes his plane into a Martian tripod has his transmission cut off mid-sentence as well.
* LargeHam: Welles' opening narration is ''very'' hammy. He is more restrained when performing as Professor Pierson within the program.
* MoodWhiplash: Terrifying reports of Martian spaceships landing on Earth? We'll get back to that in a second, but first, here's Ramon Raquello and his orchestra!
* NewMediaAreEvil: Latter-day research has found that most people weren't taken in by the faux-news format (or at least did little more than call police to ask what was happening) and that newspapers embellished the facts to make radio look bad ([[http://books.google.ca/books?id=GeWm-zM3NEoC&lpg=PP1&dq=Little+Green+Men,+Meowing+Nuns+and+Head-Hunting+Panics:&pg=PA219&redir_esc=y#v=onepage&q&f=false seems to be the most likely]]).
* PeopleFarms: The rather unhinged militia veteran that Pierson meets in Newark--the only living person he finds between Grover's Mill and New York City--anticipates that the good folks of soft middle-class America will submit themselves to the Martians and live on people farms.
* PhonyNewscast: UrExample, TropeMaker. This is the format for the first two-thirds of the show, as a program of dance music is interrupted by increasingly urgent news reports about gas explosions on Mars and mysterious objects plummeting to Earth in New Jersey. See WeInterruptThisProgram below.
* RealTime: For roughly the first third of the program, up to the death of reporter Phillips, as radio bulletins break the news of the Martian invasion. Even before the PhonyNewscast portion of the show ends, the RealTime part is basically abandoned, as the show skips ahead to military confrontations with the Martians and the Martian advance on New York.
* SettingUpdate: Welles moved the setting of the story from H.G. Wells's Victorian England to the United States of TheThirties.
* SparedByTheAdaptation: Pierson, the Ogilvy {{Expy}}, survives the invasion, unlike his novel counterpart.
* SwitchingPOV: The first part is comprised of various reports and interviews from different people. The last part follows a lone professor.
* ThisJustIn: The studio begins to overflow with reports of the Martian walkers arriving and destroying power lines and transport routes.
* ToServeMan: At least part of the reason the Martians invaded is, apparently, to eat people.
--> '''Pierson''': I've seen the Martians...feed.
* WeAreExperiencingTechnicalDifficulties: After Phillips's broadcast is cut off by him being burned up by the heat ray.
* WeInterruptThisProgram: The first ten minutes of the show involves "Ramon Raquello and His Orchestra" playing Thirties dance music, with the plot occasionally interrupting to provide breaking news.