On October 30th 1938, “The War of the Worlds” was a Halloween episode of the radio series The Mercury Theatre on the Air directed and narrated by Orson Welles as an adaptation of H. G. Wells’s novel The War of the Worlds (1898). It was performed and broadcast live at 8 pm ET over the CBS Radio Network. Wikipedia
Based on the H.H.Wells novel ‘War of the Worlds’ the story takes us through a Martian invasion of the Earth. The radio adaptation used news style broadcasts with the voice of Orson Welles and featured a cast of actors.
You can read more about the production and its aftermath here: