Just after eight P.M. on the East Coast on Sunday, October 30, 1938, millions of American families tuned into CBS Radio had heard just 17 seconds of Ramón Raquello’s orchestra playing the tango “La Cumparsita,” live from the Meridian Room of the Park Plaza Hotel in New York, when a voice interrupted: “Ladies and gentlemen, we interrupt our program of dance music to bring you a special bulletin from the Intercontinental Radio News. At 20 minutes before eight, central time, Professor Farrell of the Mount Jennings Observatory, Chicago, Illinois, reports observing several explosions of incandescent gas, occurring at regular intervals on the planet Mars.”

After a note about spectroscope readings and a confirmation by a Professor Pierson at the Princeton Observatory that Farrell’s reports were indeed correct, Raquello’s orchestra returned to the air.

A few minutes later, another news bulletin: “Ladies and gentlemen, following on the news given in our bulletin a moment ago, the Government Meteorological Bureau has requested the large observatories of the country to keep an astronomical watch on any further disturbances occurring on the planet Mars,” the announcer said, adding that the network was working to set up an interview with the nearby Princeton Observatory.

Again, the orchestra returned. Again, a bulletin provided an update. And then, about 11 minutes into the broadcast, a breathless series of news reports and man-on-the-street interviews about a Martian craft landing near Princeton, New Jersey, started to play. Sirens, crowd murmurs, and shouted orders from concerned police punctuated the audio delivered by the field correspondent and a Princeton astronomer who had rushed the 11 miles to the scene. The reporter, Carl Phillips, said breathlessly, “Well, I hardly know where to begin—to paint for you a word picture of the strange scene before my eyes, like something out of a modern Arabian Nights.

Phillips was obviously confused and struggling to get his bearings while live on air. “I guess that’s it—yes, I guess that’s the thing, directly in front of me, half buried in a vast pit. Must have struck with terrific force. The ground is covered with splinters of a tree it must have struck on its way down. What I can see of the object itself doesn’t look very much like a meteor, at least not the meteors I’ve seen. It looks more like a huge cylinder. It has a diameter of … What would you say, Professor Pierson?”

Wilmuth Farm, near Princeton, New Jersey—the scene of the “attack” on America by monsters from Mars.

The Princeton astronomer was clearly trying to wrap his head around the scene, too. “What’s that?,” he said, caught off guard by the question. “What would you say—what is the diameter of this?”

“About 30 yards,” the professor said. A cylinder, that is, nearly the length of a football field.

Phillips moved on as the police began to push the crowd back and he located the farm’s owner, Mr. Wilmuth, who recounted the experience of the object crashing into the field. They edged closer to the object as Phillips tried to capture on his microphone a strange humming sound coming from inside. Pierson proclaimed the object, whatever it was, as definitely extraterrestrial.

Then the top of the craft opened and the Martians emerged. First came the tentacles. “Good heavens, something’s wriggling out of the shadow like a gray snake,” Phillips declared from the farm in Grovers Mill, New Jersey. “Now it’s another one, and another. They look like tentacles to me. There, I can see the thing’s body. It’s large, large as a bear and it glistens like wet leather. But that face, it … Ladies and gentlemen, it’s indescribable. I can hardly force myself to keep looking at it.”

“Well, I hardly know where to begin—to paint for you a word picture of the strange scene before my eyes, like something out of a modern Arabian Nights.

Moments later, a police officer was reportedly approaching the craft with a white flag—“If those creatures know what that means,” Phillips wondered on air—when the Martians suddenly fired a heat ray, killing everyone nearby and spreading fire across the field from the extraterrestrial craft.

The transmission cut off. The music resumed.

At around 18 minutes into the hour—8:18 P.M.—the news returned, with reports of burned bodies, mobilized militias and troops, and emergency care rushing to the scene. Another bulletin from Trenton stated that Carl Phillips had been found dead and charred. The radio studio itself, the new announcer explained, had been turned over to the state, as the military operations commenced. Eight battalions—7,000 soldiers—had surrounded the pit in New Jersey, attempting to surround and isolate whatever the strange creatures were that had caused such destruction.

Martians descend onto Earth in 1953’s War of the Worlds movie.

A Captain Lansing, from the Signal Corps, said that “all cause for alarm, if such cause ever existed, is now entirely unjustified.” The creatures, he promised, could hardly survive the military’s heavy machine-gun fire, but even as he spoke, his voice began to fill with wonder and alarm. “It’s something moving … solid metal … kind of shield-like affair rising up out of the cylinder … It’s going higher and higher. Why, it’s standing on legs … actually rearing up on a sort of metal framework. Now it’s reaching above the trees and the searchlights are on it. Hold on!” The field report cut off. No one ever heard from Captain Lansing again.

Just after 8:24 P.M., listeners were given terrifying news: “I have a grave announcement to make,” the voice said over the radio. “Incredible as it may seem, both the observations of science and the evidence of our eyes lead to the inescapable assumption that those strange beings who landed in the Jersey farmlands tonight are the vanguard of an invading army from the planet Mars.” By 8:30 P.M., word came that the U.S. Army in New Jersey had been defeated, with just 120 soldiers—of 7,000!—having survived the heat ray attack.

Communication networks were down. More Martian cylinders were reported to be hitting Earth—Buffalo, Chicago, St. Louis. People were beginning to flee cities. Martial law had been declared. They were everywhere. The nation was crumbling. The secretary of the interior, live from Washington, addressed the unfolding national emergency: “I shall not try to conceal the gravity of the situation that confronts the country, nor the concern of your government in protecting the lives and property of its people.”

And then, around 8:40 P.M., some 40 minutes into the broadcast, normality returned as a station identification break made an even more stunning proclamation: “You are listening to a CBS presentation of Orson Welles and the Mercury Theatre on the Air in an original dramatization of The War of the Worlds, by H. G. Wells. The performance will continue after a brief intermission. This is the Columbia Broadcasting System.”

Intermission

There had not been, listeners soon realized, an invasion, or epic battle, or lives lost. There had not been a Ramón or even an orchestra—just a phonograph record playing in an empty CBS studio, the tango especially chosen for its tedium. The most dramatic night of radio in American history had been a scripted performance.

A spectacular dramatist, 23-year-old Orson Welles had thrived in the entertainment industry amid the darkest days of the Great Depression thanks to a unique artistic collaboration with a producer named John Houseman, forged through F.D.R.’s Federal Theatre Project.

Orson Welles performs his CBS Radio broadcast.

In 1937, the pair launched the Mercury Theatre as a place to experiment with audacious and innovative productions and adaptations—and before long, the efforts and vision had paid off. Mercury Theatre was a wild success in its first year, and CBS picked it up to air on the radio beginning on July 11, 1938. “On the broad wings of the Federal eagle, we had risen to success and fame beyond ourselves as America’s youngest, cleverest, most creative and audacious producers to whom none of the ordinary rules of the theater applied,” Houseman wrote later.

One of their biggest opportunities came that same year, when Houseman and Welles realized a possible use for the Sunday night literary adaptations lineup, which was still so new that it didn’t even have a corporate sponsor. For the week of Halloween, Welles had wanted to do something bold and new, and “conceived the idea of doing a radio broadcast in such a manner that a crisis would actually seem to be happening,” he recalled—“a dramatized form as to appear to be a real event taking place at that time, rather than a mere radio play.” Adapting H. G. Wells’s old and somewhat heavy-handed science fiction novel, The War of the Worlds, to the modern age of radio, he thought, might do the trick.

Once it was decided, the Mercury Theatre team had only a week to translate the 1897 first-person novel about a Martian invasion of England into radio fodder and prepare for their roles. (To do so, some actors playing the announcers listened to archival broadcasts of the crash of the Hindenburg, attempting to mimic the growing terror of the announcer’s voice, as the airship had crashed and burned in real time, killing 36 people.)

The hard work paid off. It sounded like a real invasion. On the evening of the broadcast, roughly a dozen actors stood behind microphones, playing a score of characters—Welles himself played Professor Pierson, among other roles—and delivering an impressively convincing performance.

After the War of the Worlds broadcast, Welles maintained that he hadn’t meant for the program to run so long before announcing that the events were fictional.

At the end of the hour, his show complete, Welles took a moment to make a statement. “This is Orson Welles, ladies and gentlemen, out of character to assure you that The War of the Worlds has no further significance than as the holiday offering it was intended to be,” he said cheerfully. “The Mercury Theatre’s own radio version of dressing up in a sheet and jumping out of a bush and saying, ‘Boo!’”

By that point, though, the damage, had been done. In those 40 minutes, some chunk of the nation had actually panicked, setting aside the disbelief that events could ever unfold so quickly—that in less than an hour, other beings could make it from Mars and land on Earth, that state leaders and troops could mobilize emergency efforts, identify the dead, and triage the wounded, that the military could launch bombing raids and ready and deploy artillery batteries in between a few bars of tango music and issue a national address from Washington.

A spectacular dramatist, 23-year-old Orson Welles had thrived in the entertainment industry amid the darkest days of the Great Depression.

By 8:48 P.M., the Associated Press had felt it necessary to issue a national “Note to Editors” clarifying that any “queries to newspapers from radio listeners throughout the United States tonight, regarding a reported meteor fall which killed a number of New Jerseyites are the result of a studio dramatization.” The N.Y.P.D., similarly, felt the need to release a citywide teletype with the assurance that there was “no cause for alarm,” as did the New Jersey State Police, who reported, “Note to all receivers: WABC broadcast as drama re this section being attacked by Mars. Imaginary affair.”

Newspaper headlines on Halloween and the days after made it sound like America had nearly succumbed to anarchy, fueled by mass hysteria. Telephone switchboards had been overwhelmed, they claimed, and terrified families had fled into the streets—some covering their faces with wet towels to avoid the spreading poisonous gas. The New York Times reported that the broadcast had “disrupted households, interrupted religious services, created traffic jams, and clogged communication systems.”

A letter from Paul Morton, the city manager of Trenton, New Jersey, regarding the aftermath of the War of the Worlds broadcast.

In the following days and months—and, really, for the remainder of his life—Welles maintained that he hadn’t meant for the program to run so long before announcing that the events being described were fictional. The team had just been working so fast, and the changes and edits to the scripts had come so late and so quick, he explained, that no one had realized the standard station ID segment, a routine element of live radio, had been pushed back. Instead of hearing the disclaimer on the half-hour, as was expected, listeners who had tuned in to The War of the Worlds late hadn’t received any notice that the broadcast was a performance until the bottom of the hour, an inconsistency that only heightened the belief it could be breaking news.

As the years passed, The War of the Worlds became a somewhat-inflated legend of popular culture, cited as a prime example of the power of the media to spread disinformation, and our population’s susceptibility to panic, especially when it came to potential invasion and the subject of aliens. Its recipe of equal parts fact, sketchy details, public confusion, media hype, and outright myth, all helped along by a showman’s instincts and—looming in the background—some government money, would come to define discussion and debate about that very subject for decades to come.

The excitement certainly worked for Welles: His show finally landed a sponsor—Campbell’s Soup—and he landed a role directing a new movie, called Citizen Kane.

Garrett Graff is the author of The Only Plane in the Sky and Raven Rock, and an executive producer on Vice TV’s series adaptation While the Rest of Us Die, airing now. His newest book, UFO, will be published on November 14