Orson Welles (shown here in 1982) produced a radio show of "War of the Worlds" in 1938, which caused panic across America.

Pierre Guillaud/AFP/Getty Images

Before his ascendancy to icon of all things cinema, Orson Welles was a fledgling director in New Deal America. In 1938, the man who later brought the world "Citizen Kane" had an idea for a radio production that he believed would strike fear in homes nationwide. Welles, the director of a New York City-based program called "Mercury Theatre on the Air," adapted H.G. Wells' novel "War of the Worlds" for the show's Halloween episode. The adaptation of Wells' 1898 work, which chronicled an alien invasion of England, updated the story to take place in Grovers Mill, N.J., in 1938. By the middle of the hour-long program, hundreds of thousands of Americans had bought the hoax, believing that martians had actually landed on Earth. Welles wanted panic, and that's exactly what he got. But, how did he succeed in creating mass hysteria via the airwaves? Why did a radio play intended for Halloween spook leave its listeners fleeing for their lives?

The broadcast's effects were attributed to two primary factors: format and timing. Welles wanted an authentic sound for the program, and achieved it by creating a series of new bulletins describing the alien invasion as it was supposedly happening. The bulletins interrupted a seemingly ordinary music show to inform listeners of the invasion. Bulletins first began from a Princeton observatory, where a fictional reporter broke the news that astronomers were monitoring strange activity on Mars. Next came reports that a "huge, flaming object" had slammed into a Grovers Mill farm. When citizens gathered at the crash site to view the commotion, they were zapped by the object's heat ray, prompting New Jersey officials to seize control of the radio station and declare martial law. More bulletins rushed in from around the country reporting martian sightings. The Secretary of the Interior in Washington, D.C., urged people to stay calm, even as the martians were allegedly destroying cities. In the final stage of the invasion, tripods descended upon New York City, "wading the Hudson like a man through a brook." Thick, poisonous gas suffocated New Yorkers, and the signals cut in and out to indicate destruction.

After the broadcast supposedly cut out from CBS headquarters, an announcement finally came that the plot was the stuff of fiction. Welles intentionally withheld this reminder from the middle section of the show, so that anyone tuning in after the introduction had no idea of the hoax. For nearly 30 minutes, from the initial reports of explosions on Mars to the lost signals from Manhattan, there were no disclaimers. Because "Mercury Theatre" shared a time slot with the more popular "Chase and Sanborn Hour" on NBC, Welles knew that many dial-tuners would not hear the introduction to his show. He also knew when the first sketch on "Chase and Sanborn" ended, many viewers would flip to his program in favor of the musical interlude. Just as NBC listeners turned the dial, they heard the reports from Grovers Mill on CBS, and had no idea that the story was fake. In an era when Americans believed everything they heard on the radio, many were livid upon hearing of the trickery. While the broadcast received harsh criticism for sending many into a frenzy, the event took its infamous place in popular culture almost instantly. To this day, there are allusions, in both film and literature, to the night when Orson Welles pulled the greatest prank in the history of radio.