The Beginning or the End is a 1947 American docudrama film about the development of the atomic bomb in World War II, directed by Norman Taurog, starring Brian Donlevy, Robert Walker, and Tom Drake, and released by Metro-Goldwyn-Mayer.

The film originated in October 1945 as a project of actress Donna Reed and her high school science teacher, Edward R. Tompkins, who was a chemist at the Oak Ridge National Laboratory.

An entirely fictional sequence was added in which Truman agonizes over whether to authorize the attack; anti-aircraft shells are shown bursting around the Enola Gay on its bombing run over Hiroshima.

In December 1942, at the University of Chicago, under the watchful eyes of observers such as Lieutenant Colonel Jeff Nixon (Robert Walker) and international experts, scientists create the first chain reaction, under a stadium at the campus.

In 1945, following the death of Roosevelt, the new president, Harry S. Truman (Art Baker), continues to support the atomic project, now moved to Los Alamos, New Mexico.

The idea for The Beginning or the End originated in October 1945 with actress Donna Reed, and her high school science teacher, Edward R. Tompkins, a chemist at the Oak Ridge National Laboratory.

Other writers involved with the script were Robert Smith, Frank "Spig" Wead, Norman Krasna, David Hawkins, John Lee Mahin and Glenn Tryon.

[7] Lise Meitner, Niels Bohr and Sir James Chadwick all refused to allow their names to be used in The Beginning or the End, which Marx regarded as unfortunate, as it made the film's Manhattan Project scenes look like an all-American affair.

[9] Oppenheimer raised no objection to the sequence in the film in which he informed Brigadier General Thomas Farrell that the odds of a runaway explosion destroying the planet were less than one in a million, although he told MGM that he never said this.

[4] Scientists were alarmed by reports that MGM leading man Clark Gable was being considered for the role of Groves, but were relieved when Brian Donlevy was cast instead.

Donlevy usually appeared in villainous supporting roles [12] and indeed, most of the actors cast in the movie were best known for film noir: Hume Cronyn for The Postman Always Rings Twice; Joseph Calleia, for Gilda and Deadline at Dawn; and Ludwig Stössel for Fritz Lang's Cloak and Dagger.

Derogatory references to Mexicans were removed, as was an off-color joke about the effects of exposure to radioactive substances ("Is it true if you fool around with that stuff you don't like girls anymore?"

Another inaccuracy, independent of necessary military secrecy, is the portrayal of anti-aircraft shells bursting around the aircraft on the bombing run, as the attack on Hiroshima was not opposed.

[17][Note 1] The film twice refers to supposed specific leaflet drops on the target for ten days in advance of the mission warning the citizens of the forthcoming raid.

[21] This incident in which "Cochran" receives a fatal dose of radiation while assembling the Hiroshima bomb is a highly fictionalized reference to the deaths of Harry Daghlian and Louis Slotin, members of the Manhattan Project who died after contact with radioactive material on 21 August 1945 and 21 May 1946.

[24] Although The Beginning or the End was the first film to depict the story of the atomic bomb, both critics and the public were confused by the attempt to merge real events in a docudrama form.

Bosley Crowther of The New York Times commented that "despite its generally able reenactments, this film is so laced with sentiment of the silliest and most theatrical nature that much of its impressiveness is marred.

"[25] Variety described the film as a "portentous tale in broad strokes of masterful scripting and production",[26] and a "sum credit of everybody concerned that the documentary values are sufficiently there without becoming static".