In addition to Welles, the Mercury players included Ray Collins, Joseph Cotten, George Coulouris, Martin Gabel, Norman Lloyd, Agnes Moorehead, Paul Stewart, and Everett Sloane.

[1] In 1935, John Houseman, director of the Negro Theatre Unit in New York, invited his recent collaborator, 20-year-old Orson Welles, to join the project.

[5] That production was followed by an adaptation of the farce Horse Eats Hat[6]: 334  and, in 1937, Marlowe's Doctor Faustus[6]: 335  and Marc Blitzstein's socialist musical The Cradle Will Rock.

Blitzstein played a battered upright piano while the cast, barred from taking the stage by their union, sat in the audience and rose from their seats to sing and deliver their dialogue.

[9] The Mercury Theatre began with a groundbreaking, critically acclaimed adaption of The Tragedy of Julius Caesar that evoked comparison to contemporary Fascist Italy and Nazi Germany.

[12] The cast included Joseph Holland (Julius Caesar), George Coulouris (Marcus Antonius), Joseph Cotten (Publius), Martin Gabel (Cassius), Hiram Sherman (Casca), John A. Willard (Trebonius), Grover Burgess (Ligarius), John Hoysradt (Decius Brutus), Stefan Schnabel (Metellus Cimber), Elliott Reid (Cinna), William Mowry (Flavius), William Alland (Marullus), George Duthie (Artemidorus), Norman Lloyd (Cinna, the poet), Arthur Anderson (Lucius), Evelyn Allen (Calpurnia, wife to Caesar), Muriel Brassler (Portia, wife to Brutus),[7]: 186  and John Berry (extra).

[6]: 341 The Mercury Theatre's second production was a staging of Thomas Dekker's Elizabethan comedy The Shoemaker's Holiday, which attracted "unanimous raves again".

[14]: 47–50 Geraldine Fitzgerald, a fellow member of the Gate Theatre company while Welles was in Dublin, was brought over from Ireland for her American debut as Ellie Dunn.

Other cast were Brenda Forbes (Nurse Guinness), Phyllis Joyce (Lady Utterword), Mady Christians (Hesione Hushabye), Erskine Sanford (Mazzini Dunn), Vincent Price (Hector Hushabye), John Hoysradt (Randall Utterword) and Eustace Wyatt (The Burglar)[17] The fourth Mercury Theatre play was planned to be a staging of Too Much Johnson, an 1894 comedy by William Gillette.

[10]: 353 The Mercury Theatre had moved to Hollywood late in 1939, after Welles signed a film contract which would eventually result in his debut, Citizen Kane, in 1941.

It opened at the St. James's Theatre, New York, on March 24, 1941 (just a month before Citizen Kane premiered), and received excellent reviews, running to 114 performances.

[10]: 362 "The Mercury Theatre was killed by lack of funds and our subsequent move to Hollywood," Welles told friend and mentor Roger Hill in a conversation June 20, 1983.

The Campbell Playhouse briefly continued after Welles's final performance in March 1940, with a truncated third season broadcast thereafter without the Mercury Theatre, but it was not a success.

Orson Welles's notoriety following "The War of the Worlds" broadcast earned him Hollywood's interest, and RKO studio head George J. Schaefer's unusual contract.

Welles was allowed to develop the story without interference, cast his own actors and crew members, and have the privilege of final cut, unheard of at the time for a first-time director.

Welles then considered adapting Cecil Day-Lewis' novel The Smiler with the Knife, but realized that this relatively straightforward pulp thriller was unlikely to make much impact for his film debut.

The writer had only received two screenplay credits between 1935 and his work on Citizen Kane and needed the job, his reputation having plummeted after he descended into alcoholism in the late 1930s.

He understood their desire to control projects and he knew they were expecting him to do an exciting film that would correspond to his "The War of the Worlds" radio broadcast.

Welles's RKO contract had given him complete control over the production of the film when he signed on with the studio, something that he never again was allowed to exercise when making motion pictures.

The discarded 40 minutes of scenes by Welles were burned, and detailed, telegraphed instructions from him suggesting further compromises to save the film were thrown away, unread.

This truncated version of The Magnificent Ambersons had a limited released in two Los Angeles cinemas in July 1942, where it did indifferently, and like Citizen Kane, the film lost RKO hundreds of thousands of dollars.

One of the first changes initiated by his successor, Charles Koerner, was to fire Welles from RKO, and his entire Mercury unit was removed from the studio and closed down.

The film's concept was loosely defined as an anthology of stories about different Americans being united against fascism, and it was hoped that a Pan-American song-and-dance number could be recorded.

He finished his Journey scenes in the small hours of the morning he left for Brazil, and Foster directed the rest of the film to Welles's specific instructions.

RKO found Journey into Fear too eccentric in its original form, and kept the film for a year before releasing it in 1943, by which time they had cut over twenty minutes.

While Welles was in Brazil, he sent Foster to Mexico to direct one of the sequences of It's All True (based on the short story "My Friend Bonito", about a boy and his donkey), while he began to develop the rest of the film.

Not wishing to leave, Welles remained in Brazil with a skeleton crew which he funded himself, but eventually had to return when he ran out of film and RKO refused to send him any more.

The footage was long presumed lost (though some of it was found again in 1985 and incorporated into a partial restoration in 1993), and Welles was unable to find a directing job for over three years, and even then, only for a formulaic low-budget thriller.

[29] One book was released under the Mercury Theatre imprint, with accompanying sets of records: This was in fact a revised omnibus version of three volumes released in 1934 under the umbrella title of Everybody's Shakespeare, published by the 19-year-old Welles and his former school teacher & lifelong friend Roger Hill, by the Todd Press, the imprint of the Todd School for Boys where Welles was a pupil and Hill became Headmaster.

[31] In addition to this, a great number of Mercury Theatre on the Air and Campbell Playhouse radio plays were subsequently turned into records, tapes and CDs, in many cases decades after their broadcast.